Dissertations / Theses on the topic 'Reed warbler'

要旨pdfファイル:タイトル「オオヨシキリにおける性分配」
Kyoto University (京都大学)
0048
新制・論文博士
博士(理学)
乙第10195号
論理博第1366号
新制||理||1132(附属図書館)
UT51-99-S312
(主査)教授 山岸 哲, 教授 米井 脩治, 助教授 今福 道夫
学位規則第4条第2項該当

Thesis (Ph. D.)--West Virginia University, 2009.
Title from document title page. Document formatted into pages; contains ix, 85 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references.

Obligate brood parasites rely solely on other species, the hosts, to incubate their eggs and raise their offspring, which often reduces the host’s reproductive output. This reproductive cost has led to the evolution of anti-parasite adaptations among hosts, which in turn, has led to better trickery by parasites, a process termed an evolutionary arms race. The objective of this thesis was to investigate host-parasite coevolutionary arms races to address questions of host-use diversity. Host diversity varies dramatically among brood-parasitic species, but reasons for variations in host-use among brood parasites are not well understood. In Chapter 2, I address questions on host diversity specifically, whereas I address questions about coevolutionary interaction between hosts and parasites in Chapters 3, 4 and 5 using two host-parasite systems, one in New Zealand and one in North America. Chapter 2 investigates if host diversity is constrained by aggressive nest defence behaviour. I compared the nest defence behaviour of the exclusive host of the shining cuckoo Chrysococcyx lucidus lucidus on the main islands of New Zealand, the grey warbler Gerygone igata, to two other potentially suitable hosts that are not currently parasitised, the fantail Rhipidura fuliginosa and the silvereye Zosterops lateralis. The results suggest that grey warblers are as aggressive as fantails and silvereyes towards shining cuckoos at the nest and thus, host specialisation in shining cuckoos in New Zealand, at least, does not appear to be the result of nest-defence constraints imposed by potential but unused host species. Chapter 3 investigates if red-winged blackbirds Agelaius phoeniceus, a species that typically accepts the eggs of parasites, recognises, as indicated by changes in incubation behaviour, when they have been parasitised by brown-headed cowbirds Molothrus ater. Recognition without rejection suggests that rejection may be context-dependent but the results suggest that red-winged blackbirds do not recognise when their nests have been parasitised by brown-headed cowbirds, at least at the egg stage. This study was the first to investigate if hosts that almost invariably accept the eggs of parasites recognise when they have been parasitised. Chapter 4 investigated the possibility of coevolutionary arms races occurring through olfactory channels in contrast to earlier work that focussed only on visual and auditory cues. Recent research has revealed that olfactory abilities in birds are more common than previously thought. Uropygial gland secretions are posited to be a key source of avian body odour and its composition has been found to vary among species and individuals as well as between the sexes. I compared gas-chromatography (GC-FID) traces of shining cuckoo preen wax to the GC-FID traces of the grey warbler, the only host of the shining cuckoo in mainland New Zealand, as well as the preen wax of seven other species for evidence of mimicry. Preliminary results suggest there is evidence for mimicry and the potential for odour-based nestling discrimination in grey warblers. Further tests recording the response of grey warblers to odour-manipulated nestlings are necessary. Finally, in Chapter 5, I investigated the response of the song thrush Turdus philomelos, a species that rejects the eggs of the common cuckoo Cuculus canorus and conspecifics at intermediate and low frequencies, respectively, to nest-odour manipulations using the preen wax of conspecifics and heterospecifics. The results suggest song thrush do not use odour to assess the risk of parasitism at least as indicated in terms of changes in incubation behaviour. Investigations of the role of olfaction in avian brood parasite systems can provide a better understanding of brood-parasite coevolution. Only by considering all channels of communication can we be sure to completely understand the coevolutionary dynamics between brood parasites and their hosts.

Acrocephalus warblers have gone through the adaptive radiation during last severalmillion years, which gave rise to thirty one species occupying mainly Eurasia,Africa and Australia. The majority of species are morphologically very similar,however, they differ in ecological requirements, migration strategy, and song.Interspecific hybridization seems to be quite common among Acrocephaluswarblers, not only between sister species, but also between more distantly relatedtaxa. The main goal of this study was to determine whether this hybridization leadsto gene flow between species and which factors affect the rate of interspecific geneflow. For this purpose we conducted population-genetic analysis in three Europeanspecies of the Acrocephalus warblers of the subgenus Notiocichla: reed warbler (A.scirpaceus), marsh warbler (A. palustris), and blyth's reed warbler (A. dumetorum).Our results based on the analysis of sequence data from eight nuclear loci indicate,that gene flow between the studied species occurs, but only in one direction. Thegene flow is higher between genetically more related species than betweenecologically more similar species. We also estimated that the reed warbler and themarsh warbler diverged approximately 1,1 million years ago. The blyth's warblerand ancestor of the reed and marsh warbler...

The aim of this work was to study the occurrence, abundance and distribution of breeding population of model species Reed Warbler (Acrocephalus scirpaceus) at selected locations. Subsequent evaluation is based on the monitored nesting parameters: nest height above water surface, water depth, distance of the nest from unvegetated water surface, the distance of the nest from the nearest fixed point, and number of stalks on which the nest was built. Diet spectrum was also detected. The results were statistically analysed in order to find out if and how these factors could influence nesting success and density of Reed Warbler population. Marginal influence on nesting success was found out only in these parameters: the number of stalks (the nests with three stalks was the most successful) and the distance from the fixed point. Successful nests were about 26% further (1.8 m) than the unsuccessful nests that could be explained by the predator factor. The most numerous insect orders in selected locations were Diptera (60%), Hymenoptera (21%) and Araneae (12%).

7 Abstract Bird nests protect eggs and nestlings, allowing the parents to leave their offspring and subsequently return to them. Their thermoregulatory properties reduce energetic costs of incubation and brooding of nestlings. For all these reasons, nests are key structures for the reproduction of a majority of avian species and as such they should be subject to natural selection. Several hypotheses describing selection pressures which affect the size of nests or some of their parts have been suggested. In my PhD thesis, I investigated some of them in the great reed warbler (Acrocephalus arundinaceus) - an open nesting passerine species with very variable nest size. For this purpose, I used a large dataset of several hundred measured great reed warbler nests, nest enlargement experiments and an experiment with artificial nests. In accordance with previous studies, we did not find that nest size affects the probability of common cuckoo (Cuculus canorus) brood parasitism, while it was influenced by other factors, such as timing of breeding, reed density around the nest and nest visibility from the nearest potential cuckoo perch site. More interestingly, we found that cuckoos adjust their nest-searching strategy in relation to availability of host nests. When host nests were scarce, cuckoos parasitized all of...

The aim of this thesis was to find out the extent of the predation of the Eurasian Reed Warbler (Acrocephalus scirpaceus) during the laying period in the South Bohemian Region. The survey was done by means of artificial nests containing fake eggs. Additional goal of the thesis was to evaluate the factors that can influence the predation according to measured nest parameters, such as the distance of the artificial nest from free water surface, the depth of water below the nest and the distance from the nearest tree.

One of the best ways how hosts may defend their clutch against brood parasitism is recognition and rejection of parasitic eggs. It has been documented that ability to percept UV light in birds affects their behaviour. By using a spectrophotometer we found that Reed Warbler (Acrocephalus scirpaceus) eggs and Common cuckoo (Cuculus canorus) eggs differ mainly in brightness but also in UV hue. We investigated the influence of birds' UV vision on recognition and rejection of parasitic eggs. Therefore we performed three experiments to reveal the role of eggshell UV reflectance on egg rejection in this host. In the first experiment, we parasitized clutches with artificial white eggs differing only in UV reflectance (UV- and UV+). In the other two, we experimentally reduced UV reflectance from conspecific and host own eggs. We used a UV light blocker, which did not influence the reflectance shape in the other parts of spectra. As a control we used a group of conspecific and own eggs coated in Vaseline, which did not affect eggshell reflectance. In each experiment, we monitored host response to parasitic eggs. Because the Reed Warbler's eggs reflect UV radiation themselves, we expected that white UV- eggs would be rejected as well as the eggs coated in UV blocker at a higher rate than white UV+ eggs and...

Nests are key structures for the reproduction of majority of avian species and as such they should be subject to natural selection. Six hypotheses have been suggested to explain variance in avian nest size. In my master thesis I evaluate their validity in the Great Reed Warbler (Acrocephalus arundinaceus). First two hypotheses describe responses of nest size to predation and brood parasitism. These two selection pressures may lead to the reduction of nest size, but no evidence of their impact on nest dimensions was obtained. However, I found a significant but negative relationship between the probability of nest predation and soft nest height. No such relationship was found between the probability of brood parasitism and nest size characteristics. The incidence of brood parasitism was affected only by nest visibility from the nearest cuckoo perch site and distance from open water. More visible nests suffered heavier parasitism while those located deeper in reed beds were better protected from cuckoo parasitism. Another four hypotheses describe selection pressures which favour large nests or some of their functional parts. The thermoregulatory hypothesis, the sexual display hypothesis and the nest support hypothesis did not explain nest size variation. I found support for the clutch size hypothesis,...

Dissertação de mestrado em Ecologia, apresentada ao Departamento Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
Reed beds are associations of hydrophyte vegetation that includes species of different families. They are also the natural habitat of specialized fauna such as migratory passerines who make stopovers during their migration between Europe and sub-Saharan Africa. This study assesses the quality of two reed beds in Central Portugal, Paul do Taipal and Paul da Madriz, for two insectivore passerine species, Acrocephalus scirpaceus (Reed Warbler) and Acrocephalus schoenobaenus (Sedge Warbler), similar in physiology but with contrasting migratory strategies and feeding habits. Ringing data from 12 years was used to evaluate habitat use for both study species and to determine productivity of breeding Reed Warblers. Environmental factors were used to explain stopover duration and body weight variation during spring and autumn migration. The birds' body condition was assessed and compared between species, seasons and age. Blood samples were taken to assess triglycerides and glucose blood levels, which are considered to distinguish migratory strategies. Abundance of food items present in the environment was determined by counting arthropods in the field to determine possible differences in stopover quality, with emphasis on the Sedge Warbler's preferred food, Hyalopteris prunis aphids. Finally, bird faeces were collected and examined to assess bird diet and preference in both reed beds. This study shows that Paul do Taipal was used more extensively than Paul da Madriz for both species. North Atlantic Oscillation and Northern Annular Mode values between December and March were the environmental parameters more correlated with stopover duration for both migratory seasons, whereas precipitation in North Africa and wind speed in Portugal were the most important parameters to explain body weight variation in spring and autumn migration, respectively. The body condition of Reed and Sedge Warblers were both greater during the autumn migration than during the spring migration. Productivity of Reed Warbler has been increasing in Paul do Taipal, despite the reduction in adults and juveniles. Triglycerides values differed between species and glucose between seasons with concentrations higher in Sedge Warblers and the autumn migration, respectively. Arthropod abundance varied for almost all orders between months, with higher numbers in summer. As expected, the peak of abundance of aphids coincided with the peak of passage by Sedge Warblers, but the relationship between the two variables was not significant. Food items most consumed by both passerines in both reed beds were Coleoptera and Hymenoptera. According to Ivlev Indices, there was a preference for Coleoptera and Hymenoptera in Paul do Taipal for both species and a preference for Coleoptera, Hymenoptera, Hemiptera and Diptera in Paul da Madriz for Reed Warblers. These results show that Paul do Taipal seems to be a better stopover site due to increased abundance and diversity of food items and use by both Sedge and Reed Warblers. Environmental parameters are very important in determining the stopover duration of these two passerines. Metabolite blood levels are in accordance with Reed Warbler making stopovers in Portugal before and after crossing the Mediterranean, while Sedge Warblers do not seem to fatten up in Portuguese reed beds.
Caniçais são associações de plantas hidrófitas que incluem espécies de várias famílias. São também o habitat natural de fauna especializada, tal como passeriformes migradores que fazem paragens durante a sua migração entre a Europa e a África subsariana. Este estudo avalia a qualidade de dois caniçais no centro de Portugal, Paul do Taipal e Paul da Madriz, para duas espécies de passeriformes migradores, Acrocephalus scirpaceus (Rouxinol-pequeno-dos-caniços) e Acrocephalus schoenobaenus (Felosa-dos-juncos), semelhantes fisiologicamente mas com estratégias migratórias e hábitos alimentares contrastantes. Doze anos de dados de anilhagem científica foram usados para avaliar o uso de habitat para ambas as espécies de estudo e determinar a produtividade de Rouxinóis reprodutores. Fatores ambientais foram usados para explicar a duração de paragens e variação de peso durante a migração primaveril e outonal. A condição corporal dos pássaros foi determinada e comparada entre espécies, épocas e idades. Amostras de sangue foram recolhidas para avaliar níveis de triglicerídeos e glucose no sangue, que se consideram poder distinguir estratégias migratórias. A abundância de items alimentares presentes no ambiente foi determinada através de contagens de artrópodes no campo para determinar possíveis diferenças na qualidade das paragens, com ênfase na comida preferida da Felosa, afídeos Hyalopteris prunis. Finalmente, foram recolhidas fezes das espécies de estudo e examinadas para determinar a dieta e preferência das aves em ambos os caniçais. Este estudo mostra que o Paul do Taipal foi usado mais extensivamente do que o Paul da Madriz por ambas as espécies. Os parâmetros mais correlacionados com a duração de paragem para ambas as épocas de migração foram os valores da North Atlantic Oscillation e Northern Annular Mode entre Dezembro e Março, enquanto a precipitação no Norte de África e a velocidade do vento em Portugal foram os parâmetros mais importantes para explicar a variação de peso na migração primaveril e outonal, respectivamente. A condição corporal dos Rouxinóis e das Felosas foram maiores durante a migração outonal do que durante a migração primaveril. A produtividade dos Rouxinóis tem vindo a aumentar no Paul do Taipal, apesar da redução de adultos e juvenis. Os valores de triglicerídeos foram diferentes entre espécies e a glucose entre épocas, com concentrações mais altas nas Felosas e na migração outonal, respectivamente. A abundância de artrópodes variou para quase todas as ordens entre meses, com valores mais altos no verão. Tal como esperado, o pico de abundância de afídeos coincidiu com o pico de passagem das Felosas, mas a relação entre as duas variáveis não foi significativa. Os items alimentares mais consumidos por ambos os passeriformes nos dois caniçais foram coleópteros e himenópteros. De acordo com os Índices de Ivlev, houve uma preferência por coleópteros e himenópteros no Paul do Taipal por parte de ambas as espécies e uma preferência por coleópteros, himenópteros, hemípteros e dípteros no Paul da Madriz por parte dos Rouxinóis. Estes resultados mostram que o Paul do Taipal parece ser um melhor local de paragem devido à elevada abundância e diversidade de items alimentares e por ser utilizado tanto por Felosas como por Rouxinóis. Os parâmetros ambientais são muito importantes para determinar a duração de paragem destes dois passeriformes. Níveis de metabolitos no sangue estão em conformidade com os Rouxinóis fazerem paragens em Portugal antes e após atravessarem o Mar Mediterrâneo, enquanto as Felosas não parecem engordar nos caniçais portugueses.

My study was aimed to describe the antipredator behaviour of Barred Warbler against five avian mounted dummies differing in the level of threat they represent for the Barred Warbler: Eurasian Sparrowhawk (Accipiter nisus), Eurasian Jay (Garrulus glandarius), Black-billed Magpie (Pica pica), Red-backed Shrike (Lanius collurio), and Domastic Pigeon (Columba livia f. domestica) using the experiments carried in the vicinity of the nests with fledglings of Barred Warbler. The next goal of my study was to discover the relationship between the Barred Warbler and the Red-backed Shrike nesting together.