Дисертації: "Gulls"

1

Veitch, Brian G. "Diet choice and reproductive success of great black-backed gulls (Larus marinus) and impacts on local breeding seabird populations /." Internet access available to MUN users only, 2003. http://collections.mun.ca/u?/theses,161494.

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2

Cook, Aonghais. "Landscape use by gulls (Larus spp.)." Thesis, University of Newcastle Upon Tyne, 2009. http://hdl.handle.net/10443/2037.

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In contrast to the negative impacts of landscape change on many aspects of biodiversity, scavenging bird species, like gulls (Larus spp.), have reacted positively and expanded their ranges. This in tum has brought a number of problems, including; damage to town centres, an increased risk of disease transmission to humans, domestic animals and livestock, an increased risk of collision with aircraft and a threat to vulnerable seabird populations. A great deal of money has been invested in measures to mitigate these problems. However, these have often been hampered by a failure to understand the ecology of the system concerned. This study employs a variety of statistical techniques to investigate factors related to the spatial and temporal distribution of gulls, the possible problems they may cause and the efficacy of measures to reduce the impact of these problems. Using structural equation modelling (SEM) it was possible to show that in contrast to other groups, like corvids which use landfill sites close to their roosts throughout the year, gulls rely most heavily on landfill sites as a source of food during the winter. However, analysis of the spatial distribution of winter gull roosts using negative binomial generalised linear models (GLMs) showed that only roosts of the black-headed gull (Larus 'ridibundasv were positively influenced by proximity to landfill sites. In contrast to the winter, when roosts were widely distributed, during the summer roosts had a coastal distribution. The problems posed by gulls to air safety and human health were investigated by analysing the spatial patterns of accidents and the incidence of salmonella carriage by 3 wild birds. In the first, bivariate k-means clustering revealed that strikes on Royal Air Force (RAF) aircraft by gulls were clustered within the 6 km surrounding major (>1000 individuals) gull roosts and landfill sites. These results were used to identify additional areas capable of supporting large numbers of gulls, and hence likely to represent a threat to aircraft in the future. I used survival analysis to investigate temporal and spatial patterns in wild bird salmonella. Passerines were more likely to be infected with salmonella than non-passerines and further analysis was indicative of gulls having a higher rate of salmonella infection than other non-passerines. Salmonella prevalence in wild birds was greatest during the winter and spring, and in areas with large populations of cattle. Having investigated the factors determining where gulls were and the risks they posed to aircraft safety and human health, I analyse the efficacy of a range of management techniques to control problem gull populations, using linear mixed effects models (LMEs). This revealed that techniques with occasional lethal events were the most effective. By using a range of statistical techniques, it was possible to disentangle a series of complex and often interacting relationships between gulls, the landscape and humans.

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3

Gamble, Jennifer R. "Suboptimal Foraging Behavior by Herring Gulls." W&M ScholarWorks, 2000. https://scholarworks.wm.edu/etd/1539626250.

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4

Keane, Shannon E. "Effects of Herring Gulls and Great Black-backed Gulls on Breeding Piping Plovers, South Monomoy Island, Massachusetts." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35908.

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The large population of breeding Herring Gulls and Great Black-backed Gulls on South Monomoy Island, Cape Cod, Massachusetts has been thought to negatively affect the breeding success of the threatened Piping Plover. Following the Piping Plover Recovery Plan s call for gull colonies to be removed from Piping Plover breeding sites, in 1996, the USFWS conducted gull removal on part of South Monomoy Island. We determined relative gull abundance on South Monomoy Island from 1998-2000 by counting gulls within 100-m radius plots located on the shoreline. We quantified Piping Plover behavior and habitat use by conducting instantaneous and 5-minute behavioral observations. We quantified characteristics of Piping Plover nesting habitat by measuring characteristics along random transects. We measured gull abundance, beach width, and prey abundance, and then used logistic regression to determine what habitat characteristics influenced Piping Plover nesting area selection. We monitored Piping Plover reproductive success and population fluctuations on South Monomoy Island. Gull abundance in the gull-removal area was lower than gull abundance in the reference area throughout the Piping Plover breeding season. The difference in gull abundance between the areas did not affect Piping Plover behavior, nest success, chick survival, or productivity. We found that gull removal did not result in an increased Piping Plover population on the island. In both management areas, prenesting plovers preferred to forage in moist substrate habitats. Wide backshore and open vegetation habitats characterized nesting areas. Broods spent most of their time foraging and preferred moist substrate habitats when available. Plovers were not prevented from occupying more suitable habitat by large gulls. Fewer large gulls were observed near prenesting plovers, plover nests, and plover broods than near random plots. Fewer large gulls were observed in plover nesting areas than in unused areas when the nesting areas were defined by all area within 100-m or 500-m of a plover nest. We argue that this apparent spatial separation between Piping Plovers and large gulls is due to different habitat preferences among the species. We found that gull removal on South Monomoy Island did not result in increased Piping Plover reproductive success, and large gulls did not affect breeding Piping Plovers on South Monomoy Island from 1998-2000.
Master of Science

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5

Lamont, Christine Rae. "Sex allocation and reproductive costs in a gull with a long breeding season." Thesis, Lamont, Christine Rae (2004) Sex allocation and reproductive costs in a gull with a long breeding season. PhD thesis, Murdoch University, 2004. https://researchrepository.murdoch.edu.au/id/eprint/143/.

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The Silver Gull is a small gull (265 - 450g), which exhibits sexual dimorphism, with males larger than females. It has a protracted laying period of about 8 months over the winter on Penguin Island in Western Australia. The Silver Gull was studied on Penguin Island from 2000 to 2002. Completed clutches were removed from breeding pairs to induce repeat laying in order to determine the effect of increased reproductive effort on maternal body condition, egg production ability, offspring sex ratio and chick rearing capacity. Increased egg production had no significant effect on maternal body condition as measured by condition index, derived from mass divided by a measure of skeletal size. The seasonal period, divided into thirty-day intervals, had a significant impact on female condition index, with a decline in condition toward the end of the breeding season. While male condition also appeared to decline at the end of the season, this pattern was not significant. The initiation of laying varied between the three years of the study. The earliest occurred in 2000, which also experienced earlier rainfall than the later two years. Egg size and mass decreased throughout the breeding season although the number of eggs in a clutch did not decline. The size and mass of the eggs was significantly affected by the laying history of the parents, although this effect was dependent on the year in which the eggs were produced. The minimum interval required by Silver Gulls to replace a lost clutch is about 14 days. This interval increased from the start of the breeding season, but then declined toward the end, as summer was approaching. Laying interval increased significantly as the number of clutches produced by the parents also increased, up to 4 clutches in total. As more clutches were produced past this point, the laying interval became shorter. The probability of a replacement clutch being produced after clutch removal, declined as the clutch number increased and as the season progressed. Individuals that laid clutches with a larger mean mass were more likely to lay a replacement clutch. Increasing reproductive output caused a decline in the proportion of clutches that were replaced after clutch removal. The proportion of clutches that were replaced also varied between the years with the highest rates of replacement seen in 2000 which was also the year that experienced the earliest start in laying. The size of the original clutch in terms of its mean mass and volume was related to the size of the replacement clutch, but this relationship varied according to the timing of laying. During 2000 and 2001 male offspring predominated in the first two clutches produced by Silver Gulls. Further clutches that were produced demonstrated a sex ratio skewed toward females, the smaller sex in this species. Offspring sex ratio was close to equality in 2002 with very little effect caused by increased egg production. There was no effect of year, season or the laying history of the parents on hatching success. Growth rate in chicks was influenced by the year in which the chick hatched, the period during the season in which the chicks hatched, its sex and the laying history of the parents. The relationship between chick growth and the laying history, however, was complex with no consistent pattern emerging in terms of the performance of chicks from each treatment group. While the chicks from control groups generally grew faster than the chicks from manipulated parents, those individuals that were laid or raised by manipulated parents that had laid at least three clutches in total also performed well. Using the two main measures of reproductive success in the current study, egg production and chick rearing, those birds that were induced to lay multiple replacement clutches, were able to maintain a high level of condition and reproductive success. It is proposed that in the Silver Gull, only those individuals with a high level of condition continue to lay replacement clutches. If the female is unable to produce well provisioned eggs with a high chance of success, the breeding attempt is abandoned. Despite no loss of condition detected in female Silver Gulls with increasing clutch number, there was a significant shift in the offspring sex ratio toward females, indicating that strategies were in place to cope with the increased reproductive effort incurred as a consequence of repeat laying. Protracted laying in this species allows replacement of lost clutches only after maternal condition has been regained after laying.

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6

Lamont, Christine Rae. "Sex allocation and reproductive costs in a gull with a long breeding season /." Access via Murdoch University Digital Theses Project, 2004. https://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050617.102950.

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7

Kim, Miran. "Eggs, incubation and hatching asynchrony in gulls." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/526/.

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Birds can influence the embryonic development through incubation behaviour because avian embryos develop using parent’s body heat. Although previous studies assumed that incubation behaviour influences hatching patterns, few studies have studied the effect of incubation behaviour during egg-laying and early incubation on hatching patterns due to difficulties to determine onset of incubation during egg-laying. I investigated whether incubation behaviour during egg-laying and early incubation affects hatching patterns in gulls using measurements of mean nest attendance and daily change of nest attendance. Hatching patterns were influenced by incubation behaviour during egg-laying and early incubation behaviour. As parents spent more time in their nests, a brood hatched more synchronously and hatching success of the first-laid eggs increased when gulls laid relatively smaller first-laid eggs than other pairs. Within-clutch variation in eggshell colour related to daily change of incubation behaviour. This might relate to hormonal change during egg-laying. Increase of prolactin initiates incubation and accompanies decline of steroid hormones which relate to accumulation of eggshell pigments. Hatching patterns may also be influenced by accelerated development of last-laid eggs. When eggs were swapped to increase interval between eggs, last-laid eggs of herring gulls accelerated their development to catch up. Accelerated development may increase the survival of chicks from last-laid eggs by reducing the disadvantage of small size within a clutch. However, the costs of accelerated development seem to appear during the embryonic period. Hatching success was low in eggs with accelerated development, although there were no differences in growth rate and early nestling survival between accelerated and control last-laid eggs. Eggshell characteristics might be a factor affecting hatching patterns because they are related to embryonic metabolism. Hatching duration was not related to eggshell thickness and total functional area, but chicks which hatched from eggs with higher proportion of mammilllary cone contact area took longer to hatch. Chicks hatched from thicker eggshells showed longer “head plus bill” at hatching and grew faster in skeleton size after hatching. Diet during egg-laying and early incubation affected nest attendance. Females which consumed more marine food during egg formation had lower nest attendance during egg-laying and early incubation. This may relate to longer foraging time required to obtain marine food. In conclusion, this thesis suggests that parents can influence hatching patterns by altering incubation behaviour during egg-laying and early incubation and hatching patterns also may be affected by accelerated development of last-laid eggs, diet during egg-laying and early incubation and eggshell characteristics (proportion of mammillary cone contact area).

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8

O'Connell, Mark John. "An ecological approach to the management of gulls, in particular the lesser black-backed gull Larus Fuscus (L. 1758)." Thesis, Durham University, 1995. http://etheses.dur.ac.uk/5358/.

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A study of gull management was made at a large colony of Lesser Black-backed Gulls Ljxrus fuscus on Tambrook Fell, Lancashire. Approximately 18,000 gulls presently breed at the site, and the area utilised by the gulls extends over 6 km2 on three private estates. The main studies were conducted on the Abbeystead Estate between 1992 and 1994. The reasons for increases in the numbers of several gull species in many parts of the world during the 20th century are presented, as well as the conflicts with humans caused by these increases. The practical and moral aspects of managing gulls are evaluated, as well as the conflicts likely to result from recent increases in the urbanisation of several Larid species. The need for management strategies to incorporate up-to-date knowledge of gull demography, density dependence, breeding biology and behaviour are discussed in the light of the limited success of past attempts at managing gulls. Experiments to entirely clear specific areas of the Tambrook Fell Gullery by disturbing breeding gulls are described. The aim was to ameliorate local problems by reducing the extent of the colony using non-lethal management techniques. Disturbance was carried out in a series of 2.25ha experimental plots. Audio, visual and physical disturbance methods, presented singly or in combination, were used to investigate their ability to exclude gulls and prevent breeding. The number of gulls using the plots and the number of nests built were compared with numbers on control plots. Gulls showed habituation to all disturbance methods, although the number of gulls using a plot was reduced during disturbance and a proportion of the original number of gulls were totally excluded. Only where two disturbance methods were utilised on the same plot was breeding completely prevented. It was demonstrated that disturbance was more effective when initiated prior to the start of nest building and when conducted at the edge of the colony, and that disturbance by human presence is an effective method of preventing breeding. In the year following disturbance, only a very few gulls attempted to utilise the disturbed areas, and the need to establish a 'sink' area for birds displaced by disturbance is discussed. In two seasons, a total of 75ha were cleared of breeding gulls. This was 23% of the Abbeystead Estate and 11 % of the total gullery area. This was the first time in over thirty years of management efforts at the colony, that the extent of the gullery was successfully reduced. Models are presented to show the effects of the 1978- 1988 culls on adult survivorship and recruitment into the breeding group at Tambrook Fell. The relative effects of management strategies aimed at survivorship and productivity are discussed. A study was made to quantify the percentage of nests built by gulls at the colony that are not subsequently laid in. Behavioural differences between pairs that failed to lay eggs and pairs that successfully bred are presented. In the past, calculations of the number of breeding gulls at the colony assumed that one nest represented one pair. This was shown not to be true and a correction factor (multiplier) of 0.61 was calculated to allow counts of nests at the colony to be converted to the number of breeding pairs.

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9

McClellan, Rachel Katherine, and n/a. "The ecology and management of Southland's black-billed gulls." University of Otago. Department of Zoology, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090827.110233.

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The black-billed gull (Larus bulleri) is a small gull that nests in dense colonies on gravel-bedded rivers in southern New Zealand. This dissertation describes research undertaken in Southland in 2004-2006 that investigates black-billed gull population decline and its causes. Historical ground counts of nests were calibrated with aerial photography of colonies and population trends analysed. The decline in breeding birds on Southland's four main rivers was equivalent to 6.0%/year (SE 1.8) or 83.6% in 30 years justifying the species' present listing as Endangered. Aerial monitoring is a poor index of the breeding population and major temporal variation was identified in counts. All re-sighted second-year birds exhibited natal dispersal and -70% left the natal catchment. Forty one percent of birds banded as adults also dispersed to other catchments. Breeding dispersal is apparently unrelated to previous breeding success and the availability of the previous year's colony site, and dispersing birds did not move as groups. Southland's black-billed gulls constitute a single inter-mixing population. Black-billed gulls selected sites on islands and banks according to availability, and selected rivers consistent with the number of gravel patches. Site vulnerability to floods varied significantly. Re-use of colony sites was positively influenced by use in previous years, the extraction of gravel, site stability and low weed cover. Widespread introduced weeds on colony sites preventing nesting and may have increased flooding risk. Colony size was related to colony area, which was related to gravel patch size. Investigation of historical changes in breeding habitat availability in Southland indicated a major reduction in gravel habitat on the Lower Oreti River between 1976 and 2002 due to river works including gravel extraction. On the Waiau River, Manapouri Dam construction in 1970 initially increased gravel areas, since reversed in the mid Waiau, and caused a 75% decline in the number of islands. Gravel patch sizes are still declining on the Lower Oreti and possibly the Mid Waiau. Hundreds of gravel patches remain on Southland rivers. Over 5000 nests in 21 colonies were monitored during incubation. Colony nest success was most influenced by colony location, averaging 90.1% (SE 2.1) on islands within rivers, and 66.8% (SE 2.2) on riverbanks, indicating that terrestrial predators exert the greatest influence on productivity. Breeding success, the mean number of fledglings produced per nest by colony, varied between 0 and 0.88 fledglings (mean 0.32, SE 0.08). Both parameters were positively related to colony size. The three smallest colonies failed to breed successfully, suggesting the presence of an Allee effect. Deterministic matrix models were used to investigate population trends using survival and productivity estimates for the closely related Kaikoura red-billed gull (L. novaehollandiae scopulinus). Adult survival, followed by breeding success and survival of first year birds, had the greatest influence on population projections. Improvements in most parameters are probably required to reverse the decline of Southland's black-billed gulls. Predation and disturbance by introduced mammals and the native black-backed gull (L. dominicanus) had the greatest impact on black-billed gull productivity. Most human disturbance is insignificant compared to predator disturbance, but illegal shooting of large numbers of adult gulls has major impacts in smaller sub-populations. Damming and excessive water abstraction reduces island habitat due to lowering of flows. Major climatic events such as droughts, and chemical ingestion through a diet dominated by agricultural invertebrates, are potential major threats about which little is known. Management actions including the collation and analysis of all unpublished black-billed gull count datasets, a thorough test of the accuracy of aerial monitoring, trialling of decoys to attract colonies to nest on islands, predator control at bank colonies, targeted weed control on high quality sites, advocacy and education and further research are recommended.

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10

Hart, A. D. M. "Winter territoriality of herring gulls at Walney Island, UK." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370265.

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11

Gusmão, Carolina Ramalho Rosado. "Wild animals clinical medicine and surgery - Botulism in gulls." Master's thesis, Universidade de Évora, 2019. http://hdl.handle.net/10174/26153.

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This report was developed in the context of the Integrated Master's Degree in Veterinary Medicine carried out by the author and was based in her curricular externship at two wildlife hospitals/rehabilitation centres, one located in Spain and the other in the United Kingdom. There are two main parts to this report. The first one includes a description of the activities performed by the author during the externship and data about the animals admitted at both centres. The second part includes a monograph about Botulism in Gulls and a case report of a Lesser Black-backed Gull (Larus fuscus) with botulism. Botulism is one of the most important diseases in wild birds worldwide. Outbreaks of this disease can have high mortality rates and a large impact on wildlife populations; Resumo: Clínica e Cirurgia de Animais Selvagens - Botulismo em Gaivotas Este relatório foi desenvolvido no âmbito do Mestrado Integrado em Medicina Veterinária e foi baseado no estágio curricular realizado pela autora em dois hospitais/centros de recuperação de animais selvagens, um localizado em Espanha e o outro no Reino Unido. Este relatório está dividido em duas partes principais. A primeira inclui uma descrição das atividades desenvolvidas pela autora durante o seu estágio e dados sobre os animais admitidos nos dois centros. A segunda parte inclui uma monografia sobre Botulismo em Gaivotas e um caso clínico de uma Gaivota-d ’asa-escura (Larus fuscus) com botulismo. O botulismo é uma das doenças mais importantes do mundo em aves selvagens. Surtos desta doença podem ter elevadas taxas de mortalidade e um grande impacto nas populações de animais selvagens.

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12

Halley, Duncan. "Behaviour, ecology and recruitment of immature guillemots, Uria aalge." Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/15060.

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Guillemots have been studied on the Isle of May since 1980. Between 184 and 581 individually identifiable birds were ringed as chicks each year since 1983. Cumulative known survival rates varied from 14-39% for cohorts at least 3 years of age. Survival rate was highly significantly negatively correlated with the number of hours of gale force winds in the three months after a cohort first goes to sea. Immatures did not return to the colony until at least 2 years of age. The proportion of a cohort attending the colony increased, cohorts arrived at the colony earlier in the season, and individuals were seen more often up to the age of 4-5. Experienced individuals arrived earlier, were seen more often, and were more likely to recruit than inexperienced birds of the same age. Two and 3 years olds but very few older birds visited sea rocks below the colony; all ages were seen on top ledges and on sites within the breeding colony. Immatures tended to visit the same subcolony repeatedly; older cohorts were more sedentary. Guillemots were highly philopatric to their natal subcolonies as prebreeders and recruits. Recruitment age varied from 3 years to 8+, median 6. Recruits fledged 0.26 chicks/pair compared to 0.79/pair in the breeding population as a whole. Recruits arrived earlier in the year of recruitment, and in the previous year, than same-aged birds which did not recruit. Substantial numbers of immatures from other colonies visited the Isle of May and Isle of May bred birds were observed elsewhere. Non-native immatures were seen fewer times than natives. Activity at the colony varied little between immature cohorts, but suggested increasing competitive ability with age. The results are discussed in relation to wider issues in seabird behaviour and ecology.

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13

Raven, Susan Jane. "Aspects of the ecology of gulls in the urban environment." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/5069/.

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A survey in 1994 recorded nearly 14,000 pairs of Larus gulls of four species nesting on buildings in Britain and Ireland. The majority of these records involved Herring Gulls, although large numbers of Lesser Black-backed Gulls were also observed. Since the last such survey in 1976, Lesser Black-backed Gulls had shown the highest rate of increase. Despite the sharp decline in the numbers of Herring Gulls breeding in Britain and Ireland since the mid-1970s, numbers nesting on roofs had continued increasing, albeit at a lower rate than before. New developments since 1976 included increasing numbers nesting inland and on the roofs of large industrial buildings. The study of a colony of Herring Gulls and Lesser Black-backed Gulls nesting on one such industrial building showed that the breeding success of these birds, although lower than that found for roof-nesting birds at more dispersed colonies, was higher than that at many traditional colonies. Low nest density, shelter for chicks and safety from predators were thought to be important contributors to this success. In addition, die colony was situated very close to the sources of food, agricultural land and urban areas, found to be most important in die diet of Herring Gulls nesting there. A review of dietary studies of roof-nesting Herring Gulls found that, despite the location of such colonies in urban areas, urban sites were not always an important source of food. The reduction in availability of one urban source of food, untreated sewage, was found to have little effect upon the gulls using an urban stretch of river. In particular, neither of the species causing most problems in urban areas, the Herring Gull and Lesser Black- backed Gull, decreased in number; in fact, numbers of these species nesting on buildings in the area increased considerably.

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14

Soares, Susana Patrícia Veloso. "Paretic syndrome in gulls (Laridae) in the south of Portugal." Master's thesis, Universidade de Lisboa. Faculdade de Medicina Veterinária, 2014. http://hdl.handle.net/10400.5/6554.

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Dissertação de Mestrado Integrado em Medicina Veterinária
RIAS, a Portuguese wildlife rehabilitation centre located in Algarve, has been admitting a substantial high number of seagulls, since its opening in October of 2009, with consistent clinical presentations pertaining to a paretic syndrome without cues of a particular disease. This preliminary study describes the clinical signs and microbiological, parasitological, toxicological and pathologic findings of paretic gulls received between 2009 and 2012. It tries to understand if there is an association between the manifestation of this disease and the different species and age classes affected. It seeks to determine possible relations between the geographic distribution of the cases and specific potentially problematic areas or human activities. All in order to additionally determine a probable cause for this disease taking into consideration the species affected, region where the animals were rescued and diseases that could explain the findings observed like: Newcastle disease, Salmonellosis, Aspergillosis, Sarcocystosis, Botulism, Algal toxicosis, Copper/Lead/Mercury intoxication, Organophosphorus/Carbamate poisoning and Thiamine deficiency. Additionally, a treatment trial with three therapeutic protocols (activated charcoal, fluid therapy and thiamine supplementation) was attempted to evaluate their influence in the outcome of the rehabilitation process and their value as a tentative diagnostic tools. Accordingly, digital records of 780 gulls were analyzed, as well as, results of more specific diagnostic ancillary tests used in carcasses and tissue samples in the centre and submitted to the Faculty of Veterinary Medicine of the University of Lisbon. From the 780 admissions, 148 gulls (18,97%) were found to have this paretic syndrome while alive, with L.fuscus and sub-adults being probably the classes most affected (p=0,02;p=0,00005). All these gulls, upon admission, were thin and dehydrated and the most frequent clinical signs documented were: depressed mental status without loss of conscious (58,8%); diarrhoea (43,9%), flaccid cloacae (70,3%); generalized muscular weakness (48,6%), moderate muscular weakness (46,6%); posterior paresis (69,6%) and moderate paresis (71,6%). Approximately half of the 148 gulls died while in rehabilitation and gross necropsy findings of paretic gulls were also unspecific and overall inconsistent. However, a high number of these gulls including dead admissions had a thin-walled cloacae distended with diarrhoea and the intestines were also displaying compatible signs of inflammation: oedema, vascular congestion and fluid faeces (32/71). Evidences of opportunistic diseases or development of confounding ailments like probably Aspergillosis were also noted. The differences between the therapeutic protocols were irrelevant (p=0,7422) and could not diagnose this condition. No pathogenic agent (bacterial or parasitic) capable of causing this syndrome was identified in the carcasses submitted (n=9). The necropsy examination and histopathology lesions reported in the faculty were inconclusive as to the cause of the paresis. Lead and Copper levels, analyzed in 2 gulls, were below what is considered in the literature as indicative of toxic. Nevertheless, in one of the gulls submitted a liver sample was positive for the presence of an organophosphorus compound, which could be in accordance with the high association measured between the spatial distribution of the proportion of paretic cases and density of several crops per municipality (Rho>0,5;p<0,05). In this moment, the data here compiled and the results obtained are still insufficient to determine or exclude the diseases in discussion as causes of this syndrome. Inconsistent use of ancillary tests results, paucity in the knowledge of ethologic and ecologic features of these birds in this region, irregularities in the retrieval of sick birds and tourism are some of the factors that may be influencing these results and should be addressed in future investigations.
RESUMO - SÍNDROME PARÉSICO EM GAIVOTAS (LARIDAE) NO SUL DE PORTUGAL - RIAS, centro de recuperação de animais selvagens localizado no Algarve, desde a sua abertura em Outubro de 2009 tem recebido um número elevado de gaivotas com um quadro clinico consistente com paresia, sem causa conhecida. Este estudo preliminar descreve os sinais clínicos e achados microbiológicos, parasitológicos, toxicológicos e anatomo/histopatológicos de gaivotas com parésia recebidas entre 2009 e 2012. Tenta igualmente perceber se existe uma associação entre a manifestação desta doença e as diferentes classes de idade e espécies afectadas. Procura determinar relações possíveis entre a distribuição geográfica dos casos e áreas/actividades humanas especificas e potencialmente problemáticas na área em estudo. Tudo com o intuito adicional de descobrir a causa provável desta doença tendo em consideração as espécies afectadas, região onde foram resgatadas e doenças que poderiam explicar os achados reunidos: Doença de Newcastle;Salmonelose;Aspergilose;Sarcocistose;Botulismo;Fitotoxicose;Intoxicação por cobre, chumbo, mercúrio;Intoxicação por organofosforados/carbamatos e Deficiência em tiamina. Três protocolos terapêuticos (carvão activado, fluidoterapia e tiamina) foram igualmente testados para avaliar os respectivos efeitos no processo de reabilitação e o seu valor diagnóstico. Desta forma, foram analisados registos de 780 gaivotas em conjunto com resultados obtidos de métodos de diagnóstico auxiliar mais específicos de carcaças e amostras recolhidas e analisadas no centro ou enviadas para a Faculdade de Medicina Veterinária da Universidade de Lisboa. Das 780 admissões, 148 larídeos (18,97%) exibiam em vida este síndrome, sendo provavelmente as classes mais afectadas: L.fuscus e sub-adultos (p=0,02;p=0,00005). Todas as gaivotas afectadas encontravam-se magras e desidratadas, sendo os sinais clínicos mais frequentemente documentados: depressão do estado mental (58,8%); diarreia (43,9%), cloaca flácida (70,3%); fraqueza muscular generalizada (48,6%), fraqueza muscular moderada (46,6%); paresia dos posteriores (69,6%) e paresia moderada (71,6%). Aproximadamente metade destes animais morreu no decurso da reabilitação e as lesões encontradas em necrópsia foram igualmente inespecíficas e inconsistentes. Contundo, um elevado número destes animais, incluindo admissões de animais mortos, apresentavam recurrentemente cloacas com parede finas e distendidas por diarreia e os intestinos apresentavam também sinais compatíveis com inflamação (32/71). Achados de doenças oportunistas ou capazes de provocar sinais/lesões semelhantes foram também reportados (e.g. Aspergilose). As diferenças obtidas entre os diferentes protocolos foram consideradas irrelevantes (p=0,7422) e incapazes de diagnosticar esta doença. Nenhum agente patogénico (bacteriano ou parasita) capaz de causar parésia foi identificado nas carcaças enviadas (n=9) e resultados de análise anatomo-histopatologia das lesões encontradas foram inconclusivos quanto à causa deste síndrome. Níveis de chumbo e cobre, analizados em amostras de fígado de 2 animais, encontravam-se abaixo do que é considerado na literatura como indicativo de tóxico. No entanto, em uma amostra de fígado de uma das gaivotas enviadas foram detectados resíduos de um organofosforado,o que poderá ser concordante com a elevada associação medida entre a distribuição espacial da proporção de casos com parésia e a densidade de diversas culturas por município (Rho>0,5;p<0,05). Neste momento, toda a informação aqui compilada é ainda insuficiente para determinar ou excluir as doenças em discussão enquanto causas. O inconsistente uso de métodos de diagnóstico auxiliar, a escassez de informação relativa à etologia e ecologia destes animais nesta região, irregularidades na recolha de animais doentes e o turismo são alguns dos factores que podem estar a influenciar estes resultados e deverão ser tidos em conta no futuro.

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15

Guerra, Correa Carlos Guillermo. "Life History Biology of the Desert Nesting Seagull Larus modestus." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc331083/.

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Gray gulls Larus modestus are unique among birds of northern Chile as the only species nesting in the interior Atacama Desert, and the only seagull nesting far (30 - 100 km) from surface water. During breeding-nesting (August - February) gray gulls congregate on the coast of northern Chile where they feed and initiate courtship. As early as August, breeding pairs commute daily to the inner desert to establish nesting territories, round-trip distances of 60-200 Km. During incubation (30 days) and brooding (7 days) adults alternate daily foraging flights to the coast. Afterwards, both adults forage daily for their chick(s) until fledging (ca. 60 days). Foraging flights and thermoregulatory costs during the period of maximal solar radiation, when ground temperatures may reach 61 C in the day and drop to 2 C at night, have selected for adaptations which minimize those costs: tolerance of hypothermia and hyperthermia; dark plumage; low egg-shell water vapor conductance; low standard metabolic rate; elaborate repertory of thermoregulatory behavior which allow adults to take advantage of microclimatic variations in the desert and minimize costs relative to a sympatric congenor, Larus belcheri scheduling foraging flights to take advantage of optimal atmospheric conditions and presence of forage fish (anchovies) close to the surface; scheduling migration to coincide with anchovy production and levels of interspecific competition; and reduced clutch size ( ≤ 2) relative to most seagulls. Periodic El Nino-Southern Oscillations (ENSO), which reduce principal food items of gray gulls, have selected for 'bet hedging" tactic by which L. modestus either ceases reproduction or varies clutch size between one and two, as observed during and after the 1982-83 ENSO. During a typical reproductive season, breeding pairs allocate a minimum of 39 percent of their net metabolized energy (NME) to foraging flights. Including energy content of eggs, females have an overall reproductive effort (RE=reproductive costs/NME) of 35.1 percent of 122,086.8 KJ per year.

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16

Hesp, Lee. "Age-related foraging behaviour in the black-headed gull (Larus ridibundus)." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238231.

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17

McCulloch, Fiona M. "Reproductive behaviour in a small inland colony of black-headed gulls (Larus ridibundus)." Thesis, University of St Andrews, 1990. http://hdl.handle.net/10023/15061.

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This study was carried out over three breeding seasons at a small marsh-nesting black-headed gull (Larus ridibundus) colony. Two of the years proved to be atypically hot and dry, resulting in the drying out of parts of the colony. This facilitated predation by foxes and resulted in almost complete breeding failure in these two years. Synchronisation of breeding was evident but the average clutch size was smaller than generally recorded for black-headed gulls. There was a tendency for third laid eggs and third hatched chicks to have the highest mortality rate, and third hatched chicks put on less weight during their first three days of life than all other chicks. Pairs of gulls that did not successfully retain their territories and lay eggs spent less time on the territory than those that were successful. The unsuccessful males were also more restless and more aggressive than successful males. In general, the gulls spent most time on the territory during the incubation stage, although partners spent the most time together on the territory during the pre-egg stage. The territory was never left unattended during the incubation stage, but it was occasionally deserted during the pre-egg stage, and increasingly deserted as the chick stage proceeded. In one year, but not another, males spent most time on the territory and incubating during the egg stage, while females spent most time on the territory and brooding during the chick stage. The gulls were most aggressive during the pre-egg stage and least aggressive during the incubation stage, and the males played the greater role in defence during the pre-egg and egg stages. The sexes shared equally the feeding of the chicks and became less eager to feed the chicks as they grew. The number of feeds given per hour per chick decreased with increasing brood size.

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18

Dunlavey, Eric G. "Age-Related Differences in the Prey-Dropping Behavior of Herring Gulls (Larus argentatus)." W&M ScholarWorks, 2001. https://scholarworks.wm.edu/etd/1539626308.

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19

Yauk, Carole Lyn. "Germline minisatellite mutations in herring gulls, induced mutations at colonies situated near steel mills." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ51024.pdf.

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20

Stienen, Eric Willem Maria. "Living with gulls trading off food and predation in the Sandwich Tern Sterna sandvicensis /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/291341373.

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21

Yauk, Carole Lyn. "Germline minisatellite mutations in herring gulls : induced mutations at colonies situated near steel mills /." *McMaster only, 1998.

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22

Kim, Sin-Yeon. "Effects of environmental conditions on reproductive biology in herring and lesser black-backed gulls." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414406.

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23

Raveendran, Lethika. "The effect of intravenous salt loading on osmoregulation of hydrated glaucous-winged gulls, Larus glaucescens." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26519.

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Renal function of fresh water acclimated Glaucous-winged Gulls, Larus qlaucescens, was studied during infusion of hypotonic and hypertonic NaCl. Two experimental protocols were followed. In one, the closed urine collection system (CCS), ureteral urine was collected using catheters glued over ureteral openings of a supine, previously anesthetized gull. In the other, the open urine collection system (OCS), ureteral urine was collected through a funnel placed in the urodeum of a standing, unanesthetized bird. In both protocols, there was continuous saline infusion of hypotonic (hydration) and hypertonic (LOAD) saline at 0.286 ml⋅min⁻¹. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), ml(kg⋅min) ⁻¹, were determined by ¹⁴C-polyethylene glycol (PEG) and ³H-para-aminohippuric acid (PAH) clearances. Plasma vasotocin (PAVT, pg⋅ml⁻¹) was measured. At the end of 4 h hydration with 0.02 M NaCl, urine flow was high but matched infusion rate only in CCS birds (CCS, 0.29 ± 0.05; OCS, 0.17 ± 0.03 ml⋅min⁻¹), GFR (CCS, 5.56 ± 0.85; OCS, 5.36 ± 0.77) and ERPF (CCS, 15.80 ± 1.60; OCS, 14.35 ± 1.65) were high; urine sodium (UNa+) concentration was low (CCS, 15.0 ± 7.3; OCS, 36.4 ± 6.0 mEq⋅1⁻¹), UNa+ excretion was low (CCS, 6.38 ± 4.2; OCS, 5.19 uEq⋅min⁻¹) ; urine/plasma PEG ratio (U/PPEG) was high (CCS, 22.4 ± 4.4, OCS, 39.6 ± 8.5); free water clearance (CH₂O) was positive (CCS, 0.143 ± 0.011; OCS, 0.052 ± 0.019 ml⋅min⁻¹) , and PAVT was low (ccs,14.7 ± 7.4; OCS, 16.1 ± 2.4) in both groups. Immediately following infusion of 5 M NaCl, GFR, ERPF and urine flow increased for about 10 mins. Fifteen minutes later, the GFR of CCS gulls fell to 70% of pre-load values (P < 0.05) and in OCS gulls, GFR and ERPF fell to 64% (P < 0.01) and 61% (P < 0.05). Eighty mins after infusion of 5 M NaCl, the GFR and ERPF of CCS gulls returned to pre-LOAD levels, but remained low in OCS gulls. Twenty-five minutes after salt load, urine flow had fallen to 49% (P < 0.05) and remained low. In OCS gulls, urine flow had fallen to 13% (P < 0.001) after 185 mins. In both CCS and OCS gulls, UNa+ concentration and excretion increased significantly. Sixty minutes after salt load, UNa+ excretion returned to pre-LOAD levels but UNa+ concentration remained high in CCS (111.7 ± 57.5) and OCS (132.8 ± 12.5) gulls. U/PPEG attained 134.3 ± 26.5 in CCS and 181.2 ± 32.4 in OCS gulls. CH₂O fell significantly (P < 0.05) in CCS gulls but remained unchanged in OCS gulls. Mean PAVT increased to 122.5 ± 5.5 in CCS and 96.0 ± 12.6 in OCS gulls. In both CCS and OCS gulls, salt gland secretion was initiated but ceased 60 mins after 5M NaCl infusion, although 60% of the load was retained in the gull.
Science, Faculty of
Zoology, Department of
Graduate

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24

Massaro, Melanie. "Investigation of causes and effects of predation by herring (Larus argentatus) and great black-backed gulls (L. marinus) on black-legged kittiwakes (Rissa tridactyla) on Gull Island, Newfoundland." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0015/MQ55522.pdf.

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25

Bays, Nathalie. "The effects of herring gulls (Larus argentatus) on the vegetation and soils of their nesting sites /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0005/MQ29651.pdf.

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26

Levy, Michael S. "Helminth communities of ring billed gulls (Larus delawarensis) collected along the St. Lawrence River and estuary." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0019/MQ40192.pdf.

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27

Løseth, Mari Engvig. "Levels and Effects of Organohalogens on Corticosterone Hormones in glaucous gulls (Larus hyperboreus) from Kongsfjorden, Svalbard." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25209.

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Long-range atmospheric transport, ocean currents, sea ice and rivers are transporting environmental contaminants into the Arctic. Some of these contaminants can reach high concentrations in the upper trophic levels in the Arctic food web due to processes of bioaccumulation and biomagnification. The present study indicates a sex-specific pattern of levels and effects of selected organohalogenated contaminants (OHCs) in the avian top predator, glaucous gull (Larus hyperboreus), breeding in Kongsfjorden, Svalbard. The aim of this present study was to report levels of OHCs and investigate whether the high levels detected in glaucous gulls can induce stress and thereby influence the stress response (measured by corticosterone concentration). No statistical differences were recorded for stress-induced or baseline corticosterone concentrations for males and female glaucous gulls. In females, a significant negative association was reported for lipid weight in blood plasma and baseline corticosterone. In male glaucous gulls, positive associations were found between levels of twenty-two OHCs and elevated baseline levels of corticosterone; indicating for the first time a “cocktail” effect of specific OHCs in blood plasma associated with high baseline levels of corticosterone in male glaucous gulls. It is suggested that the high levels of OHCs may act as a chronic stressor. The OHCs may interfere with the Arctic seabirds’ ability to respond to environmental stressors, such as climate change and food availability, by disrupting the baseline levels of corticosterone and weakening the feedback mechanisms of the stress axis. Elevated baseline levels may lead to suppression of immune parameters and reduced survival rate. Due to a small sample size assessed in the present study, more research is needed to confirm a possible relationship between the disrupted stress axis and environmental contaminants in the Arctic seabirds. 

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28

Steele, William K. "Distribution, diet and kleptoparasitic behaviour of gulls (Aves: Laridae) in the southwestern Cape Province, South Africa." Doctoral thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/8427.

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Bibliography: leaves 159-175.
The southwestern Cape coastline supports only two common, resident gull species, Hartlaub's Gull Larus hartlaubii and the larger Kelp Gull L. dominicanus. Hartlaub's Gull is endemic to southern Africa and the Kelp Gull that occurs in this region is sub-specifically distinct, L. d. vetula. Although locally abundant, both the Kelp and particularly Hartlaub's Gull have been relatively little studied. This study addressed three aspects of the two gull species' ecology related to foraging. The diet of both species was studied through direct observation and analysis of pellets, scats and stomach samples. Diet was quantified at a range of foraging habitats; (i) a sandy beach; (ii). a rocky shore; (iii) a fishing harbour; and, (iv) a refuse dump. In addition, the proportion of marine prey in the diet of Kelp Gulls at a refuse dump, a sandy beach and at archaeological sites was estimated using stable carbon isotope analysis of bone collagen. Both gulls are generalist foragers feeding on a wide and diverse range of prey species. The Kelp Gull is able to feed on a wider range of prey species than is Hartlaub's Gull due to its larger size. The preferred natural foraging habitat of the Kelp Gull is sandy beaches, where the sand mussel Donax serra is the most important prey. Present day Kelp Gull diet at an undisturbed• sandy beach includes a similar proportion of marine protein to prehistoric gull diet in the same area. Hartlaub's Gull most commonly forages on swarms of invertebrates associated with accumulations of stranded kelp e.g. Ecklonia maxima.

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29

Meathrel, Catherine Elizabeth. "The reproductive performance and body condition of silver gulls (Larus novaehollandiae) during a protracted breeding season." Thesis, Meathrel, Catherine Elizabeth (1991) The reproductive performance and body condition of silver gulls (Larus novaehollandiae) during a protracted breeding season. PhD thesis, Murdoch University, 1991. https://researchrepository.murdoch.edu.au/id/eprint/52075/.

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Silver Gulls Lams novaehollandiae were studied on Penguin Island, south-western Western Australia, during three peaks of laying over the eight month breeding seasons of 1987 to 1990. It was hypothesized that seasonal variation in their natural, food supply, would be less during the middle laying-peak, when there is no mass stranding of littoral vegetation on beaches, and that this would be reflected in the body condition of adults as well as characteristics affecting their reproductive success. Clutch-size, egg-size and egg mass did not vary annually, seasonally, or from island to island. Egg-size and mass, however, decreased during the laying sequence. The lipid and protein content of eggs was greatest during the early laying-peak and earlier in the laying sequence, and was more variable in first-laid eggs. There appeared to be no trade-off between clutch-size, egg-size and egg quality, suggesting that the first two may be heritable, whereas egg composition may reflect the body condition of the laying female. The duration of rapid yolk deposition did not vary seasonally, but did vary between females, and averaged ten days. Less yolk was deposited, and at a slower rate, in laterlaid eggs within a clutch. Day-specific growth rings in sibling eggs differed in size, suggesting that daily, yolk deposition was not maternally influenced and unique to each follicle. Embryonic growth followed the von Bertalanffy curve, was constant seasonally and between eggs, and appeared under fixed, probably genetic, control. Eggs containing developing embryos appeared to lose less water via conductance through the shell than other larids, possibly as an adaptation to the warm, mediterranean climate. Hatching success did not vary seasonally, but did vary within clutches. Since female Silver Gulls allocated more reserves to their first-laid eggs, later, smaller and less massive eggs hatched less frequently. The mass, but not the sex, of a hatchling could be predicted from egg mass. Although sex was related to egg sequence, the overall ratio was unity, and suggested that sex determination is a random, meiotic event in Silver Gulls. Hatching success was independent of egg quality, but post-hatching growth and survival were directly related to egg quality. Chicks which died had exhausted their yolk sacs. Surviving hatchlings grew exponentially during the first month of life as the water index of tissues decreased in the entire chick and in its leg musculature. Contrary to initial expectations, adult condition was maximal during the middlelaying peaks, reproductive performance was not proximately constrained by food availability to females, and the gulls were omnivorous. This study showed that the reduced clutch-size and size of later-laid eggs within clutches of Silver Gulls were not proximately controlled by the body condition of adults. Double-brooding and long breeding lifespans mean that a relatively low reproductive effort within a single laying-bout would not necessarily decrease the lifetime reproductive output of Silver Gulls relative to shorter-lived, single-brooded species of temperatenesting larids that lay clutches of three eggs.

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30

Spencer, Robert. "An empirical and theoretical investigation of kleptoparasitic foraging behaviour in mixed-species aggregations of gulls (Laridae)." Thesis, Middlesex University, 2017. http://eprints.mdx.ac.uk/22172/.

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This thesis investigated kleptoparasitism in mixed-species foraging aggregations of gulls (Laridae). Kleptoparasitism, or food stealing, is a strategy used frequently by gulls. Gull populations are increasing in urban areas despite declining overall. Understanding the role of kleptoparasitism in aiding gulls to invade urban environments was a central aim of this research. A second aim was to develop a model of kleptoparasitism using a compartmental modelling approach from evolutionary game theory and to test this using real foraging data. Fieldwork was undertaken at two study sites: a coastal site (Brancaster beach, Norfolk, UK) and an urban site (Billingsgate Market, London, UK). The focal species were the Great black-backed gull (Larus marinus), Herring gull (Larus argentatus), Black-headed gull (Chroicocephalus ridibundus), and Common gull (Larus canus), these species forage together but differ in size and competitive ability. Foraging at the sites was recorded and analysed for kleptoparasitic incidents. Three kleptoparasitic strategies were considered: aggressive, stealth and scramble kleptoparasitism. Four studies were conducted: Study 1 investigated differences in the rate of kleptoparasitism between the study sites and assessed the ecological predictors of this difference. The results showed kleptoparasitism was higher at the urban site and higher population density was the best predictor of this. Kleptoparasitism may aid invasion and increase the range of environments a gull can tolerate by helping them meet their energy needs in novel environments. Study 2 described the patterns of kleptoparasitic behaviour observed at both sites. Large species used aggressive kleptoparasitism against smaller species, and smaller species used stealth kleptoparasitism when stealing from larger species. The use of stealth kleptoparasitism by smaller, subordinate foragers was identified as an empirical example of a Marauder strategy. Kleptoparasitic strategies were used flexibly to compete for resources against opponents of different competitive abilities. Study 3 examined what strategies, other than kleptoparasitism, subordinate foragers at Billingsgate used to compete for resources. Subordinate gulls foraged for longer, stayed closer to potential food locations, arrived first at patches and took more risks to obtain food than dominants. Study 4 developed a game-theoretical model and compared this model against the foraging data for Billingsgate. The results indicated the density of different foraging behaviours at Billingsgate may be at an equilibrium, but only 23% of foragers were using evolutionarily stable strategies. This result was attributed to a one-species model being used to describe a population containing three species of differing competitive ability. Further work applying game-theoretical models to field data is needed to assess how effectively gulls use kleptoparasitic strategies, particularly in novel environments such as urban areas.

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31

LeGrow, Keith Herbert. "Distribution of marine birds in relation to water masses and fronts in the Strait of Belle Isle, northwestern Atlantic Ocean." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ54902.pdf.

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32

Haugerud, Anja Johansen. "Levels and Effects of Organohalogenated Contaminants on Thyroid Hormone Levels in Glaucous Gulls (Larus hyperboreus) from Kongsfjorden, Svalbard." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-15014.

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The glaucous gull (Larus hyperboreus) is one of the largest flying top predators in the Arctic and is exposed to rather high levels of different persistent organohalogenated contaminants (OHCs). The present study investigated whether the serum thyroid hormone (TH) levels in female glaucous gulls breeding in Kongsfjorden (79oN) may be affected by the various OHCs. A slight decrease in traditional OHCs, like polychlorinated biphenyls (PCBs) and some pesticides have been reported over the last decade, while increasing levels of new and emerging compounds like polybrominated diphenyl ethers (PBDEs) and perfluoroalkyl substances (PFASs) are detected in Arctic marine and terrestrial wildlife. Although further production of some possible endocrine disruptive chemicals have been banned by many nations, the chemicals persist, move throughout the biosphere and are potentially harmful to exposed wildlife and biota.After 35 years of contaminant research, the Svalbard glaucous gull function as a bioindicator species. Previous assessments have concluded that OHC levels were high enough to be of concern for a number of physiological effects, among them endocrine alterations. However, this is to my knowledge the first biomarker study on levels of THs in breeding glaucous gulls from Kongsfjorden. Plasma from 19 nesting female glaucous gulls was analysed for PCBs, organochlorinated pesticides (OCPs) (such as dichlorodiphenyltrichloroethane [DDT] and chlordanes) and their metabolites, PBDEs and PFASs. Total and free ranging THs were quantified using radioimmuno assay (RIA). Multivariate statistics were used to investigate the relationships between the TH levels and the explanatory variables.The PCBs represented the most pervasive compound group in the present study, as 61.3 % of the total contaminant burden in female glaucous gulls. The other contaminant groups contributed as follows: ΣDDTs (17.5 %) > ΣPFASs (14.8 %) > HCB (2.9 %) > ΣCHLs (2.7 %) > ΣPBDE (0.8 %) > ΣHCH (0.1 %). Several of the PFASs correlated significantly with the THs. Significant correlations were found between several of the long-chain Perfluoroalkyl carboxylates (PFCAs) and THs. Surprisingly, even though the PFCAs represented only 2.8 % of the total contaminant load in the present study, the PFCAs represented the most important variables explaining the variation in THs.

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Hebert, Craig Edwards. "The role of diet in regulating reproductive success and contaminant accumulation in Great Lakes herring gulls (Larus argentatus)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ41172.pdf.

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34

Melnes, Marte. "Disruptive Effects of Organohalogenated Contaminants on Thyroid Hormone Levels in Glaucous Gulls (Larus hyperboreus) breeding in Kongsfjorden, Svalbard." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25203.

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The glaucous gull (Larus hyperboreus) is a predator and scavenger occupying an upper position in the arctic marine food web. This species is exposed to high levels of a variety of anthropogenic pollutants thought to cause adverse health effects. Organohalogenated contaminants are possible endocrine disruptors, suggested to interfere with the thyroid hormone system among others. The purpose of this project was to evaluate the possible effects of the cocktail of OHCs to which glaucous gulls are exposed to on circulating thyroid hormone levels. Blood from male and female glaucous gulls were sampled during the incubation periods of 2011, 2012 and 2013 in Kongsfjorden, Svalbard in the Norwegian Arctic. The plasma was analyzed for a variety of organohalogenated contaminants, including polychlorinated biphenyls (PCBs), persistent organochlorinated pesticides (OCPs), brominated flame retardants such as polybrominated diphenyl ethers (PBDEs) as well as perfluorinated alkylated substances (PFASs). Total and unbound fractions of thyroid hormones were quantified. Multivariate data analysis was conducted to evaluate associations between contaminants and thyroid hormones. Highly chlorinated PCBs, some persistent OCPs and the emerging perfluorooctane sulfonate (PFOS) were the compounds detected at the highest levels in the present study. Females seemed to be more susceptible to disruptive effects of organohalogenated contaminants on thyroid hormone levels than male glaucous gulls. The prevailing contaminants detected were also the ones shown to significantly alter free fractions of both T3 and T4 in female glaucous gulls. The results from the present study demonstrate complex combined effects on TH levels from the environmental mixtures of halogenated organic contaminants to which glaucous gulls are exposed to in the Arctic.

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Boyne, Andrew W. "Diet and reproductive success of Herring Gulls nesting on the middle north shore of the Gulf of St. Lawrence." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ50725.pdf.

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36

Boyne, Andrew. "Diet and reproductive success of herring gulls nesting on the middle north shore of the Gulf of St. Lawrence." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21516.

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Breeding biology and diet of Herring Gulls Larus argentatus were studied on Ile Nue, in the Mingan Archipelago National Park Reserve, in the Gulf of St. Lawrence. Nesting parameters were measured 1994--1996, and fledging success and diet were followed in 1996. Clutch size was low in all three years of the study, and hatching success was low in 1995. Low clutch size and hatching success could not be explained by researcher disturbance, predation, or competition for nest sites, leaving food-stress as the most likely explanation. To reduce the biases associated with determining diet, we used four methods to estimate diet. The 1996 breeding season was divided into three periods using changes in the number of gulf pellets collected from roost sites as an indirect measure of dietary changes; these periods corresponded to the pre-spawning, spawning, and post-spawning periods of capelin Mallotus villosus. (Abstract shortened by UMI.)

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Jones, M. J. "Aspects of the ecology and behaviour of black-headed (Larus ridibundus) and common gulls (Larus canus) on urban grassland." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356108.

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Corman, Anna-Marie [Verfasser]. "Flight and foraging patterns of lesser black-backed gulls and northern gannets in the southern North Sea / Anna-Marie Corman." Kiel : Universitätsbibliothek Kiel, 2015. http://d-nb.info/1078261261/34.

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39

Dunlop, James Nicholas. "The comparative breeding biology of sympatric crested terns Sterna bergii (Lichtenstein), and Silver Gulls Larus novaehollandiae (Stephens) in south-western Australia." Thesis, Dunlop, James Nicholas (1986) The comparative breeding biology of sympatric crested terns Sterna bergii (Lichtenstein), and Silver Gulls Larus novaehollandiae (Stephens) in south-western Australia. PhD thesis, Murdoch University, 1986. https://researchrepository.murdoch.edu.au/id/eprint/52076/.

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This thesis reports an investigation of the double-nesting phenomenon, a unique pattern of anomalous, protracted breeding, reported in seabirds from mid-western and south-western Australia. In particular, it deals with the Crested Tern Sterna bergii Lichtenstein and the Silver Gull Larus novaehollandiae Stephens, two related lariform seabirds which nest in sympatry, and possibly associatively, in the Fremantle area of south-western Australia. Both species have protracted breeding seasons in the study area, superficially similar in timing and duration, and therefore provided useful subjects for a comparative study of their breeding biology. From 1979 to 1984, the reproductive cycles of the two species were examined in detail. Emphasis was placed on determining the timing and periodicity of breeding, both at the population and at the individual level, and on determining those factors involved in the ’proximate' control of the reproductive cycle. The results showed that, despite superficial similarities in breeding seasons, there were fundamental differences in biology between the two species, particularly with respect to the influence of environmental ‘proximate’ factors. These contrasts are interpreted primarily in terms of the different evolutionary origins of the two species, although the various constraints on the reproductive cycle, which are imposed by their differing nesting adaptations and feeding behaviour, are also discussed. Models of the reproductive cycle at the individual level, and of the breeding season(s) at the population level, are developed for both species. Using data for some other seabird species breeding in south-western Australia, the Crested Tern and Silver Gull models are incorporated in a general explanation of ‘double-nesting’. The views presented not only provide some insight into a unique, localised phenomenon but should also lead to a re-examination of conventional ideas about seabird breeding seasons generally.

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Oliveira, Filipa Batista Galinha de. "The most prevalent respiratory and gastrointestinal parasites in Herring Gulls -Larus argentatus- admitted in a wildlife rehabilitation centre in South-East England." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2019. http://hdl.handle.net/10400.5/18991.

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Dissertação de Mestrado Integrado em Medicina Veterinária
Herring gull (Larus argentatus) is one of the most widespread species throughout the British coastal areas. In the last 40 years, there has been a decline of 30% in the global population followed by a decrease in the natural breeding sites and sharp increase in the urban nesting populations. RSPCA Mallydams Woods, is a wildlife rehabilitation centre situated in the South-East of England that has been receiving increasing numbers of Herring gulls that end up being euthanized due to respiratory signs with the suspicion of the persistence of a parasitological agent (Cyathostoma sp.), previously identified in 2004. In the meantime, no further parasitological studies in this species were performed by the centre. Therefore, a total 65 necropsies and coprological analysis were performed in order to assess the main respiratory and gastrointestinal parasites as well as the main pathological alterations suggestive of other infectious agents. The general results showed that 32% (21/65) were positive for the presence of parasites. These results included gulls that had not received worming treatment, who showed 60% of positives (12/20) and dewormed gulls, who still showed 20% positives (9/45). Around 24.6% (16/65) presented Syngamidae eggs including two mixed infection cases, one with Porrocaecum eggs (1.54%) and the other with Contracaecum (1.54%). Among those 16 cases, 44.8% also presented visible worms in the infraorbital area of the nasal cavity. Nematodes of the species Cyathostoma lari were detected in 16.9% (11/65) of the cases and genus Syngamus in 1.54% (1/65). As to the McMaster method, it was shown that 23.1% (15/65) gulls had ˃50 EPG counts, including 9.2% (6/65) within the dewormed gulls. During necropsy procedures, signs of acute inflammation on the lungs were the most prevalent findings (30%). The longer rehabilitation periods and higher number of doses of wormer were the only factors to show significant association with the lower prevalence of parasites. This study demonstrated that the inefficacy of the worming protocol, the high animal density and presence of other infectious agents are the most probable causes of the persistence of respiratory signs within the admitted gulls. However, to the best of the author’s knowledge, this is the first parasitological study on Herring gulls performed in a British rehabilitation centre and there is a difference of 40 years between this study and the previous ones performed in wild populations, which shows that there is a serious need for more projects in this field.
RESUMO - Parasitas respiratórios e gastrointestinais mais prevalentes em Gaivotas Cinzentas (Larus argentatus) admitidas num centro de reabilitação de animais selvagens no Sudeste de Inglaterra - A gaivota-cinzenta (Larus argentatus) é uma das espécies mais amplamente distribuídas na orla costeira britânica. Nos últimos 40 anos, houve um declínio de 30% na população mundial, seguido de uma diminuição nas zonas naturais de reprodução e um aumento acentuado nas populações de nidificação urbana. RSPCA Mallydams Woods, é um centro de reabilitação de animais selvagens situado no sudeste Inglês, que tem recebido um número crescente de gaivotas cinzentas que acabam por ser submetidas a eutanásia devido à presença de sinais respiratórios com a suspeita de persistência de um agente parasitário (Cyathostoma sp.), previamente identificado em 2004. Até à data, nenhum outro estudo parasitológico na espécie foi realizado pelo centro. Deste modo, um total de 65 necrópsias e análises coprológicas foram efetuadas para avaliar os principais parasitas respiratórios e gastrointestinais envolvidos, bem como as principais alterações patológicas sugestivas de outros agentes infeciosos. Os resultados gerais mostraram que 32% (21/65) eram positivas à presença de parasitas. Estes resultados incluíam gaivotas que não receberam desparasitante, apresentando 60% de positivos (12/20) e gaivotas desparasitadas, que ainda assim apresentavam 20% de positivos (9/45). Cerca de 24,6% (16/65) apresentavam ovos do tipo dos observados na família Syngamidae, incluindo 2 casos de infeção mista, um com ovos de Porrocaecum sp. (1,54%) e outro com ovos de Contracaecum sp. (1,54%). Entre estes 16 casos, 44,8% também apresentaram parasitas visíveis na zona infraorbitária da cavidade nasal. Os nemátodes da espécie Cyathostoma lari foram detetados em 16,9% (11/65) dos casos e Syngamus sp. em 1,54% (1/65). Relativamente ao método de McMaster, demonstrou-se que 23,1% (15/65) das gaivotas tinham ˃50 EPG, incluindo 9,2% (6/65) das gaivotas desparasitadas. Durante as necrópsias, os sinais de inflamação aguda nos pulmões foram o achado mais prevalente (30%). Períodos de reabilitação mais longos e maior número de doses de desparasitante foram os únicos fatores que mostraram uma associação significativa com a menor prevalência de parasitas. Este estudo demonstrou que a ineficácia do protocolo de desparasitação, a elevada densidade de animais no espaço existente e a presença de outros agentes infeciosos no centro de reabilitação, são as causas mais prováveis da persistência de sinais respiratórios nas gaivotas admitidas. No entanto, este parece ser o primeiro estudo parasitológico sobre gaivotas cinzentas realizado num centro de reabilitação britânico e há uma diferença de 40 anos entre este estudo e os previamente realizados em populações selvagens, o que demostra a elevada necessidade de mais projetos nesta área.
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Witteveen, Minke. "The influence of a changing environment on the breeding biology and diet of Kelp Gulls (Larus dominicanus vetula) in Plettenberg Bay, South Africa." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15582.

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We live in a constantly changing world, where recent human-induced changes and climate change affect virtually every component of the Earth's surface and systems. Coastal ecosystems are particularly at risk, as one of the most utilised and urbanised of natural systems worldwide, as well as being at risk from sea level rise. This will degrade or even destroy many feeding and breeding sites. Those species colonising new habitats in an attempt to escape rising sea level and climate change related threats, will be competing for space with the growing human population and urbanisation. Although 97 of 346 seabird species (28%) are globally threatened, 57 (17%) have increasing populations, including 17 gulls (Larinae). The Kelp Gull Larus dominicanus is a cosmopolitan species with an increasing population worldwide. Kelp Gulls in southern Africa L. d. vetula are one of 15 seabird species that breed in the region, and one of only five breeding seabirds listed as Least Concern in the region. Three Kelp Gull breeding colonies in Plettenberg Bay, Western Cape, were surveyed to provide an updated count for this area. A combination of direct counts and the trial use of an unmanned aerial vehicle (UAV),were used as methods of counting nests. The direct monitoring of nests allowed for the effect of different microhabitats on the breeding performance of Kelp Gulls to be investigated, which has implications for their ability to adapt to future habitat changes. The importance of anthropogenic food items in the diet of Kelp Gulls breeding in Plettenberg Bay was explored through the use of regurgitated pellets of indigestible matter, and chick regurgitations, and how this is reflected in the time spent in various areas as shown by GPS loggers and point counts in urban areas. Another aspect of the urban adaptation of Kelp Gulls is the incorporation of anthropogenic debris in their nests, which was examined at eight breeding colonies throughout the Western Cape.

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Blight, Louise Katherine. "Glaucous-winged gulls Larus glaucescens as sentinels for a century of ecosystem change : long-term trends in population, diet, and egg production in North America's Salish Sea." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43674.

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Ecological studies characterising population trends over decades or centuries can help to describe the range of variability in a study system, with well-studied species being strong candidates for providing the long-term data required for retrospective studies. Seabirds represent useful real-time monitors of marine systems and may also play this role in studies characterizing historical ecological change. The glaucous-winged gull L. glaucescens is a generalist marine bird occurring in the Salish Sea, an urbanized coastal area of southwestern British Columbia and northwestern Washington, where it has been studied or collected since the mid-1800s. Its twentieth-century populations experienced dramatic growth followed by a steep decline, with recent trajectories unclear. I used multiple methods to characterise long-term trends in gull number, diet, and egg production, and to test hypotheses about causes of population change. My approach combined meta-analysis of historical reproductive traits, statistical modeling of population trend, and stable isotope analysis (δ¹³C, δ¹⁵N) of historical and modern gull feathers and forage fish, with modeled population trend showing a continued decline in gull numbers from the 1970s to the present. Meta-analytical results pointed to decreasing egg and clutch size and a delayed lay date over the twentieth century to the present, while stable isotope analysis showed declining feather δ¹³C and δ¹⁵N since 1860, all of which was consistent with a growing reliance by gulls on non-fish foods. Demographic modeling showed that declining clutch size and productivity were largely sufficient to account for the gull population decline, and pointed to recovery from cessation of nineteenth-century egging as being an important contributor to the increase phase. These modeling results implied that declining consumption of forage fish affected gull productivity. Additional results from stable isotope analysis also supported a hypothesis of dietary change; namely, declining forage fish C:N ratios over time indicated a decrease in fish lipid content, and thus a decline in prey quality. Overall, my results highlight the value of compiling multiple retrospective studies to better understand the complex factors affecting long-term trends in animal populations.

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Dufour, Paul. "Evolution de la migration à longue distance chez les oiseaux Reconstructing the geographic and climatic origins of long distance bird migrations Plumage colouration in gulls responds to their non-breeding climatic niche." Thesis, Université Grenoble Alpes, 2021. http://www.theses.fr/2021GRALV015.

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Si de nombreux animaux effectuent des migrations saisonnières, la migration des oiseaux demeure l’une des plus spectaculaires du règne animal et c’est d’abord parce qu’elle fascine les humains que cette migration est la plus étudiée depuis toujours. Mais malgré cet engouement précoce de la communauté scientifique, d’importantes interrogations persistent. Parmi celles-ci, les scénarios biogéographiques qui façonnent la distribution des espèces migratrices ou qui ont conduit des espèces ou des lignées entières à évoluer vers un comportement de migration saisonnière à longue distance restent peu compris.L'objectif de ma thèse était d’aborder ces questions à différents niveaux taxonomiques, afin d’étudier les implications écologiques et évolutives de la migration à longue distance chez les oiseaux. Plus précisément, (1) je me suis d’abord intéressé aux scénarios d’évolution biogéographique et des niches climatiques qui ont conduit à l’émergence de stratégies de migration géographique saisonnière à grande distance. (2) Resserrant le cadre taxonomique aux Charadriiformes, j’ai approfondi mes recherches sur la biogéographie de la migration en abordant la question du rôle de la migration dans les processus de diversification et la mise en place des gradients globaux de biodiversité. Pour mieux comprendre ces mécanismes évolutifs, j’ai également étudié (3) comment l’évolution de la coloration est reliée à l’évolution de stratégies de migration chez les Laridae et (4) l’influence de ces mouvements longues distances sur les autres évènements du cycle annuel chez une espèce d’oiseau marin de l’Arctique. (5) Enfin, à l’échelle intra-spécifique, je me suis penché sur la mise en place de nouvelles voies de migration chez deux de passereaux d’origine sibérienne pour explorer la question des rapides changements de distribution.Dans l'ensemble, les résultats de ces études montrent que les différentes facettes de l'écologie et l'évolution sont fortement intriquées pour comprendre l’évolution du comportement de migration longue distance. Ils montrent également l’importance de confronter plusieurs échelles taxonomiques et plusieurs facteurs, notamment temporels, pour appréhender l’histoire évolutive de ce comportement. Enfin, ils soulignent la difficulté de prévoir les changements de distribution des oiseaux migrateurs dans un contexte de changements globaux
Many animals make seasonal migrations, but bird migration remains one of the most spectacular in the animal kingdom and it is mainly because it fascinates humans that this migration has been the most studied historically. However, despite this early interest of the scientific community, important issues have remained unresolved. Among these, the biogeographical scenarios that shape the distribution of migratory species or that have led species or entire lineages to evolve towards long-distance migration behaviour are still poorly understood.The aim of my thesis was to address these questions at different taxonomic levels, in order to study the ecological and evolutionary implications of long-distance migration in birds. More precisely, (1) I first focused on biogeographic theories of migration evolution at a global scale, coupled with the study of the tracking of ecological niches during the annual cycle. (2) Narrowing the taxonomic framework to the Charadriiformes, I pursued my research on the biogeography of migration by also addressing the question of the role of migration in diversification processes and in the establishment of latitudinal diversity gradients. To better understand these mechanisms, I also studied (3) the selective pressures encountered during the annual cycle of a migratory bird family and (4) the influence of these long-distance movements on other events of the annual cycle in an Arctic seabird species. (5) Finally, at the intraspecific level, I investigated the establishment of new migration routes in two passerines of Siberian origin to explore the issue of rapid changes in distribution.Taken together, the results of these studies highlight how tightly the different facets of invasion ecology and evolution are interrelated in understanding the evolution of long-distance migration behaviour. They also highlight the importance of comparing several taxonomic levels and several factors, particularly temporal factors, to assess the evolutionary history of this complex behaviour. Finally, they stress the difficulty of predicting changes in the distribution of migratory birds in a context of global changes

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Santos, Fernanda de Almeida. "Análise populacional genética de Larus dominicanus através do uso de microssatélites." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/41/41131/tde-23072012-150819/.

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As alterações que a ação antrópica vem causando nos ambientes costeiros tem provocado impactos sobre as espécies a eles associadas. Larus dominicanus é uma espécie de ave marinha amplamente distribuída ao longo do Hemisfério Sul. Por possuir um hábito alimentar generalista, os resíduos da ação antrópica tem beneficiado a espécie, que, assim como outras gaivotas, vem apresentando um crescimento demográfico acelerado. O presente estudo, através do uso de marcadores de microssatélites, mostra que, apesar disso, a espécie possui uma baixa variabilidade genética, com fraca estruturação populacional, que provavelmente são o reflexo da origem recente da espécie e de uma diferenciação recente entre as populações. Múltiplas forças atuam para determinar a estruturação populacional, sendo elas o isolamento por distância, as barreiras físicas e a filopatria. Os sinais de gargalo populacional encontrados em algumas das colônias levantam a possibilidade de efeitos fundadores por colonização recente nas colônias mais ao norte da costa brasileira e redução populacional nas colônias da Argentina e da Antártica como conseqüência da última glaciação. Estes dados chamam a atenção para a necessidade de considerar as informações genéticas para a implantação de planos de manejo. Uma vez que a diferenciação entre as populações é recente, a variabilidade dentro de cada uma delas deve ser mantida. O controle populacional da espécie através de métodos diretos deve ser também acompanhado por planos de manejo ambiental, visando reduzir ou eliminar as condições que propiciam o crescimento desequilibrado dos gaivotões.
The changes in the coast that has been caused by human action has led to impacts on species associated with this environment. Larus dominicanus is a seabird species widely distributed throughout the Southern Hemisphere. The generalist feeding habits allow this species take advantage from human action, leading to population growth, which is also observed in other species of gulls. This study, through the use of microsatellite markers, shows that, despite of the population growth, Larus dominicanus has a low genetic variability, with low population structure, which probably reflects the recent origin of species and a recent differentiation among populations. Multiple forces act to determine the population structure, among them the isolation by distance, physical barriers and philopatry. Some colonies presents a bottleneck sign, raising the hypothesis of recent founder effects in the colonies to the north of Brazil and population reduction of colonies of Argentine and Antarctic as consequence of the last glaciation. These data show the need to consider genetic information for the implementation of management plans. The variability within populations must be maintained, since the differentiation between them is recent. Furthermore, the species population control by direct methods must also be accompanied by environmental management plans, to reduce or eliminate the conditions that favor the unbalanced growth of the gulls

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García-Tarrasón, Manuel. "Trophic ecology, habitat use and ecophysiology of Audouin’s Gull (Larus audouinii) in the Ebro Delta." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/286360.

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The results presented in this thesis have shown the strong dependence of Audouin’s gull from the Ebro Delta on fisheries. Foraging movements of breeding birds showed a great association with fishing activities (specially trawling), determining the most of its at-sea distribution on work days. An increase in the use of rice field habitats was also detected in absence of fishing activities (during weekends) due to the opportunistic feeding on the American crayfish. However, a key aspect presented in this thesis was the significant sex-differences in their foraging behaviour in relation to fisheries. Female Audouin’s gull tended to perform longer at-sea foraging trips on weekends compared to males, probably due to the need of feeding on high quality resources after laying instead of the easily available but lower quality American crayfish. This great dependence on fishing activities was also reflected in the resource allocation into the clutch. An isotopic δ15N enrichment in the albumen of eggs synthesized during the weekends was observed, which is attributed to an increase in the consumption of rice field resources as well as to the mobilization of female reserves. However, rice field diets were associated to lower antioxidant capacity in the eggs. Also, rice field diets were related to smaller egg size. Finally, the limiting nature of calcium (in constraining egg synthesis) and antioxidant molecules (decreasing their concentration especially in the latter eggs of the clutch) were also revealed for females.
Los resultados presentados en esta tesis han mostrado la gran dependencia de las gaviotas de Audouin del Delta del Ebro sobre las pesquerías. Los movimientos de búsqueda de alimento de las aves durante la reproducción mostraron una gran asociación con las actividades pesqueras (especialmente el arrastre durante el día, aunque también es notable la influencia de la pesca de cerco durante noche), determinando la mayor parte de su distribución en el mar los días laborables. Un incremento en el uso de arrozales fue detectado en ausencia de actividades pesqueras (durante los fines de semana). Sin embargo, un aspecto clave presentado en esta tesis fue las diferencias significativas entre sexos para el comportamiento de alimentación en relación a las actividades pesqueras. Las hembras de gaviota de Audouin tendieron a realizar viajes de alimentación más largos que los machos durante los fines de semana. Esta gran dependencia sobre las actividades pesqueras fue también reflejada en la asignación de recursos sobre la puesta. Un enriquecimiento del δ15N fue detectado en el albumen de los huevos sintetizados durante los fines de semana, lo cual puede ser atribuido a un incremento en el uso de recursos de arrozal así como a la movilización de reservas de la hembra. Sin embargo, un mayor uso de dietas de arrozal se asoció con una menor capacidad antioxidante de los huevos. También, dietas de arrozal estaban relacionadas con tamaños del huevo más pequeños. Finalmente, se puso de manifiesto la naturaleza limitante del calcio (restringiendo la síntesis del huevo) y de las moléculas antioxidantes del huevo (decreciendo su concentración especialmente en los últimos huevos de la puesta).

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46

Al-Yasiri, Mohammed Hashim Yasir. "Réservoirs environnementaux des champignons pathogènes humains : effet de l'anthropisation sur les communautés fongiques chez Larus michahellis." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM5012/document.

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Le goéland leucophée endémique dans la région méditerranéenne française. Son mycobiote intestinal n'a jamais été étudié. Ce travail visait à décrire le rôle de ces oiseaux comme réservoir et disséminateur de champignons pathogènes pour l’homme. Nous avons collecté 177 guano de goélands dans cinq sites sur le littoral méditerranéen français; La Grande-Motte, Palavas-les-Flots, Pierre-Blanche, Frioul and Riou archipels. Nous avons identifié dix-sept espèces de levure; les plus fréquentes étant Candida krusei, Galactomyces geotrichum, C. glabrata et C. albicans. On notait d’une part une augmentation de la fréquence des espèces anthropiques de levures C. glabrata et C. albicans avec l’anthropisation des biotopes des colonies de goélands dont d’isolats résistants aux antifongiques. Nous avons analysé les communautés de champignons filamenteux aérocontaminants isolés à partir des mêmes échantillons. Nous avons identifié 16 genres de champignons filamenteux. la faible diversité et abondance de champignons filamenteux dans les zones urbaines par rapport aux suburbains ou à un environnement peu affecté par l'anthropisation et l’association claire entre certaines espèces fongiques et des environnements particuliers. nous avons analysé la génétique des populations de la levure C. glabrata. Nous avons typé par MLVA, 111 isolats de goélands et 79 isolats collectés chez des patients des hôpitaux de Nîmes, Montpellier et Marseille. Nous avons observé une diversité génétique similaire entre les populations de C. glabrata isolées chez le goéland ou chez l’homme. Les isolats de C. glabrata résistants au fluconazole se distribuaient uniformément dans les deux populations
The yellow-legged gull is endemic in the French Mediterranean area. Their gut mycobiota has never been studied. This work aimed to describe their role in the spreading of potentially human pathogenic fungi with antifungal resistance. Therefore, we sampled 177 yellow-legged gull’s faecal samples in five sites along the Mediterranean littoral South of France; La Grande-Motte, Palavas-les-Flots, Pierre-Blanche, Frioul and Riou archipelagos. We identified seventeen yeast species; the most frequent were Candida krusei, Galactomyces geotrichum, C. glabrata, C. albicans and Saccharomyces cerevisiae. The frequency of the anthropic yeast species C. glabrata and C. albicans increased with the synanthropy of the gull’s colonies and antifungal resistance was found in each of the five most frequent yeast species. We further analyzed the airborne filamentous fungi species isolated from the same sample cultures. We identified 35 filamentous fungi species in 16 genera including 35 species. Both fungal diversity and abundance were low in urban area when compared to suburban ecocline or environments that were little affected by anthropogenic impact and particular fungal species were clearly associated with distinct environments. Finally, we analyzed the population genetic of the human pathogenic yeast C. glabrata, which were isolated from gulls (111 isolates) and from patients (79 isolates) in Nimes, Montpellier and Marseille hospitals, via MLVA analysis. We found that the C. glabrata populations isolated from gulls or humans shared a similar genetic diversity. Antifungal-resistant C. glabrata isolates were evenly distributed in both gull and human populations

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47

Mengler, Faron. "Gully erosion on rehabilitated bauxite mines." University of Western Australia. School of Earth and Geographical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0176.

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[Truncated abstract] Landforms rehabilitated after bauxite mining can be vulnerable to soil loss by water erosion processes. On most rehabilitated sites, management controls such as deep ripping, contour mounding and landscaped sub-catchments limit erosion. Despite these measures, severe gully erosion that is anecdotally associated with steep slopes can damage rehabilitated areas and affect downstream drinking water resources. A review of erosion dynamics reveals that gullies develop episodically and in a non-linear manner. They often initiated as a near surface process and are influenced by natural climatic drivers. Despite this, local site characteristics including soil and landform can predispose an area to gully erosion. Moreover, erosion models, becoming more-widely utilized within the mining industry, may provide useful tools with which to measure, analyse, and manage gully erosion. One of these models, SIBERIA was tested to determine its suitability for application a tool to help manage erosion risk. We first surveyed 26 eroding and erosion-prone rehabilitated hillslopes to determine the common form and setting for gully erosion on these rehabilitated bauxite mines. A conceptual model was developed to include and explore the interplay between the common causes of the gullies surveyed. The conceptual model accounts for slope steepness but suggests that additionally, certain triggers and threshold effects operating under different site conditions are as influential (or even more influential) than slope steepness as determinants of gully erosion occurrence and severity. ... Soil properties and soil erodibility had some subtle influence on landform stability and erosion risk. The most-erodible media occurred where either: mine floor material was mixed with topsoil/ overburden; and/or the topsoil/overburden layer was thin or its coverage is patchy resulting in slaking subsoil, hardsetting soil and surface crusts. When erodible surface media were combined with steeper (>8[degrees]) or longer (>50 m) slopes or with any major erosion trigger, rill and gully development was greatly intensified. The SIBERIA simulation model was calibrated and its simulated outputs were compared to known locations of gully erosion on a steep, rehabilitated pit from the Willowdale mine. At a resolution of one metre, SIBERIA was able to simulate the approximate dimensions of gullies. However, SIBERIA could not simulate the exact location of individual gully headcuts. Additionally, SIBERA was able to simulate the effect of different microtopographic surface treatments but this was only achieved by increasing the grid resolution to 25 cm and reducing the size of the area simulated due to model constraints. Locations of gully headcuts were overlain onto a grid-based, Digital Elevation Model (DEM) using a Geographic Information System (GIS). The spatial distribution of gully headcut locations was compared to DEM derivatives such as slope and flow accumulation. Positive, and predictive relationships allow between the steepness of the slope of the pre-mining landform and the cell count of the area contributing to flow (catchment), as determined by GIS, may allow a mine scale indication of erosion risk using simple GIS desktop analysis.

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Karimov, Vladimir Rustemovich. "Mathematical modeling of ephemeral gully erosion." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38230.

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Doctor of Philosophy
Department of Biological & Agricultural Engineering
Aleksey Y. Sheshukov
As the world faces an increasing demand for food due to the growing global population and the pernicious effects of land degradation, there is a need to overcome this challenge by using sustainable management practices for agricultural productions. One of the problems, which sustainable agriculture seeks to address, is the loss of topsoil due to soil erosion. Changing weather patterns also contribute to the average annual rainfall across the globe with an excess precipitation, which creates runoff and causes soil erosion. One of the significant yet less studied types of soil erosion is ephemeral gully erosion. Formed by the concentrated overland flow during intensive rainfall events, ephemeral gullies are channels on agricultural fields that can be removed by tillage operations but appear at the same location every year. Even though simplified ephemeral gully models estimate soil losses, they do not account for complicated hydrological and soil erosion processes of channel formations. The purpose of this research work is to investigate sediment sources and develop tools that can predict ephemeral gully erosion more efficiently. To achieve this goal, an experimental study was conducted on an agricultural field in central Kansas by tracking channel development, monitoring soil moisture content, and recording the amount of rainfall. Runoff and sediment loads from contributing catchment and critical and actual shear stresses were estimated by the computer model, and conclusions were made on the effect of saturation dynamics on the erosion processes. Furthermore, a two-dimensional subsurface water flow and soil erosion model was developed with the variable soil erodibility parameters which account for the subsurface fluxes and the effects on the soil detachment process. The model was applied to study the impacts of variable soil erodibility parameters on the erosion process for different soils and various antecedent soil moisture conditions. Also developed to estimate the soil losses at the field scale was an integrated spatially-distributed ephemeral gully model with dynamic time-dependent channel development. The model showed good fit by matching the experimental data. The results from this work can be used to advance the research of soil erosion prediction from concentrated flow channels and ephemeral gullies formed on agricultural fields.

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Jonsson, Carl. "Gulli Petrini - kampen för kvinnors rösträtt : Wexiöbladet och Smålandspostens syn på Gulli Petrini, kämpen för kvinnnors rätt." Thesis, Linnéuniversitetet, Institutionen för kulturvetenskaper (KV), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-71393.

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This study is about Gulli Petrini, the woman who were a pioneer in womens rights during the beginning of the 20th century, and the way that the local newspapers Wexiobladet and Smalandsposten portrayed her during her time in Vaxjo city council and Vaxjo economical chambers between 1910 and 1914. The study is based on different types of gender based theories wich i will discuss in collaboration with my result from the two newspapers aswell as the two protocols from Vaxjo city council an Vaxjo economical chambers. In the beginning of the 20th century the swedish society were very influenced by divided gender-roles. The expectations of being a woman versus being a man were strongly established so when Gulli Petrini became the first woman who got selected into Vaxjo city council, and two years later Vaxjo economical chambers, it was a bit of a sensation. During her time in her role as a local politician and as a women with strong and firm opinions she rocked the symbolical political boat. Gulli Petrini turned out to be one of many strong-minded women who helped the woman community to achieve the common goal wich was getting the right to vote in 1919.

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50

Burke, Katherine J. "Understanding gully process in two Kansas landscapes." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/20102.

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Doctor of Philosophy
Department of Environmental Design and Planning Program
Tim Keane
Gullies often form as a result of land use changes and associated factors such as soil compaction, vegetation removal and changes in rainwater infiltration. Gully erosion creates human safety hazards, soil loss, and sediment and nutrient pollution downstream. Across the globe, researchers have found a wide variety of gully growth rates and drivers (Poesen, Nachtergaele, Verstraeten, & Valentin, 2003), but after the late 1900s, very few published gully studies have been done in the United States, and fewer studies have been done in the Midwest and Great Plains regions. This gully study was conducted in two heavily-used Kansas landscapes: Fort Riley military training areas and agricultural fields in McPherson County. The purpose of the study was to quantitatively measure rates and patterns of gully erosion, as well as identify main drivers of gully initiation and growth. Results and conclusions add Kansas gully characteristics to the growing knowledge of gully erosion in other areas of the world. Gullies in both landscapes were surveyed in the field multiple times per year over three consecutive years (2012-2014) to capture patterns and rates of change. Rainfall data and land characteristics such as soils, vegetative cover, slope, and drainage area were compiled into a database to be compared to gully erosion rates in an attempt to correlate gully erosion not only to rainfall but to other land-based factors. Results show that for most Fort Riley gullies, beds are filling and banks are widening, and consistent drivers of erosion could not be determined from the data. In McPherson, gully channels are storing large amounts of sediment, though gully networks in the upper areas of the gully channels are actively widening and advancing headward. Drivers of channel change in McPherson County seem to be related to vegetative cover, slope, and early spring freeze/thaw processes. At both study locations, land use changes related to linear disturbance and reduced vegetative cover are suspected to have more of an influence on gully growth than rainfall events during the study timeframe. Objectives for best management practices are proposed for both Fort Riley and McPherson County.

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