Dissertations / Theses on the topic 'Giraffe (Giraffa camelopardalis)'

Doctor of Philosophy
The population size and range of giraffe Giraffa camelopardalis have been greatly reduced in Africa in the past century, resulting in geographical isolation of local populations and some herds surviving at the edge of the species’ preferred range. Numerous factors have contributed to these declines, but historical analysis indicates that habitat loss and fragmentation, human encroachment, disease and poaching are the main threatening processes. These processes can be expected to continue to impact on giraffe populations, particularly as human populations grow and needs for land and resources increase. This study used field data and laboratory analyses to investigate the taxonomy, behaviour and ecology of desert-dwelling giraffe Giraffa camelopardalis angolensis in the northern Namib Desert. This population resides at the extreme of the giraffe’s range. My research also complements the community-based natural resource management (CBNRM) program of the Namibian government, and provides baseline data on the current population status and structure of giraffe in the Kunene Region. The field data, genetic, habitat and forage samples used in this study were collected by myself and a number of research assistants over a period of two years (2001 to 2003), following preliminary research that I undertook between 1999 and 2001. Laboratory analysis of genetic samples was conducted by Dr R. Brenneman and his team at Henry Doorly Zoo, Omaha, NB., as well as by Mr D. Brown at UCLA, CA. Mr W. Gawa!nab and his team at the agricultural laboratory, Ministry of Agriculture, Water and Rural Affairs, Namibia, conducted chemical analyses on plant samples that form part of the giraffe’s diet. The genetic architecture of Namibian giraffe was investigated, including the samples from the desert-dwelling giraffe of the northern Namib Desert and giraffe from Etosha National Park. The results were compared with genetic profiles of giraffe subspecies throughout Africa, but in particular with G. c. giraffa which is the currently-accepted nomenclature of the Namibian giraffe. Results indicated that the Namibian giraffe has five unique haplotypes and is genetically distinct from G. c. giraffa or any other extant subspecies; it is considered here, tentatively, to represent G. c. angolensis. Furthermore, the Namibian Abstract iv giraffe has been separated from other populations for an extended period. Some gene flow has occurred between the desert-dwelling and Etosha NP giraffe population, and can be attributed to recent translocations between these regions. Within the study region, a sharing of haplotypes between three studied subpopulations indicated gene flow among giraffe throughout the northern Namib Desert, and this was confirmed by field-based monitoring. Taken together, these findings suggest that Namibian giraffe should be viewed as important for the conservation of overall genetic variation within Giraffa camelopardalis, although further investigation into the taxonomy of the Namibian form is warranted. Following these findings, I then investigated the behaviour and ecology of the desert-dwelling giraffe. As no previous study has been published on the ecology of G. c. angolensis, there is an information gap in our knowledge of this subspecies. One hundred and fifty six giraffe were identified individually using field-based identification methods and digital imagery. An assessment of the population structure and dynamics indicated marked variation in numbers, sex and age structure, herd structure and densities between three study areas. These variations possibly arose from differences in study area size, aridity, availability of forage and human impacts. I also investigated levels of associations between giraffe within the population using a simple ratio technique, and observed that increased association occurred in smaller populations; there appeared to be a matrilineal social structure. In one bull-biased population, a higher degree of association between bulls was observed compared to bulls in the other two populations. To gain further insight into the distribution and range of giraffe, I collected GPS locations from a combination of field-based monitoring and GPS satellite collars. The GPS satellite collars were the first trial of this technology on giraffe in Africa. Using Range Manager, a MapInfo animal location analysis extension program, I estimated 100% and 95% minimum convex polygon for daily, monthly and annual home range sizes of giraffe in the northern Namib Desert. Giraffe were observed to have large home ranges, with the largest individual range for a bull, Africa-wide, being recorded in this study. Large home ranges correlated with low population density, reduced diversity of forage and, in bulls, increased search areas for receptive cows. Giraffe movements occurred predominantly along riparian woodlands, although seasonal use of other habitats was recorded. Observations Abstract v Abstract vi and data from four GPS satellite-collared giraffe provided high-resolution data on daily movements, and indicated a pattern of highly biphasic movement behaviour that correlated with ambient temperatures. Diurnal activity budgets varied between the sexes, with cows spending more time feeding and resting, while bulls walked and ruminated more frequently. Juveniles rested more often than other giraffe. Seasonal variation in activity budgets was evident, perhaps reflecting use of an energy maximiser strategy for cows and an energy minimiser strategy for bulls. The establishment of artificial water points in the Hoanib River during the study period appeared to alter the seeming independence of giraffe on water in the northern Namib Desert, and also resulted in small-scale shifts in use of the riparian woodland by elephant. To investigate the diet of giraffe, I observed animals feeding in the field and also carried out laboratory analyses of the chemical content of preferred plant species. Seasonal changes in the abundance, moisture and protein content of available food plants correlated with shifts in the diet of giraffe. Giraffe impacted on their preferred forage source, Faidherbia albida, causing distinct structural changes in the individual plants and the F. albida population. This impact, combined with elephant damage and seasonal flood events, has resulted in a shift in the age structure and dynamics of the F. albida population over the past two decades. Finally, I present a brief overview on the history of conservation and management in the Kunene Region. The established CBNRM program provides a baseline for future wildlife conservation and management, of which the desert-dwelling giraffe could be an integral component for non-consumptive tourism. Long-term research on the population’s status, range, behaviour, social structure, habitat requirements, and ecology would help to provide a better understanding of the giraffe’s adaptation to the arid environment, while focussed legislation would enable increased control of communal lands and continue to benefit community-based conservancies.

Giraffes (Giraffa camelopardalis) have evolved into a unique and extreme shape. The principle determinant of its shape is the skeleton and the overarching theme of the study was to describe how this shape is achieved throughout ontogeny. Accordingly, the study had three main objectives: 1) To describe the growth of the giraffe postcranial skeleton allometrically, 2) To interpret the allometric patterns described in an evolutionary and functional sense and 3) To reconstruct the size and shape of the extinct Giraffa sivalensis using, if feasible, allometric equations obtained in this study. Secondary objectives were to a) establish if sexual dimorphism was evident in G. camelopardalis and b) determine if growth patterns in the foetus differed from those in postnatal G. camelopardalis. Data were collected from giraffes culled as part of conservancy management in Zimbabwe. The sample included 59 animals from which vertebral dimensions were taken in 48 animals and long bone dimensions in 47 animals. Body masses ranged from 21 kg to 77 kg in foetuses and 147 kg to 1412 kg postnatally, representing 29 males and 30 females. In addition to body mass, external body dimensions were recorded from each animal. Each vertebra and unilateral long bone was dissected from the carcasses and cleaned, after which dimensions were measured with a vernier calliper, measuring board or measuring tape. Vertebral dimensions measured included body (centrum) length, height and width as well as vertebral spinous process length. Long bone dimensions included length, two midshaft diameters and circumference. Allometric equations (y=bxk) were constructed from the data, with special interest in the scaling exponent (k) to illustrate regions of positively allometric, isometric or negatively allometric growth. In the first series of analyses the growth patterns of the components of the postcranial axial skeleton were analysed. The adaptations in vertebral growth to create and maintain extraordinary shape were identified as disproportionate elongation of the cervical vertebrae after birth, increasing cross sectional diameters of the cervical vertebrae from cranial to caudal and positively allometric spinal process growth. The theory of sexual selection as a driver for neck elongation in giraffes was brought into question by showing that male and female vertebral elongation rates are similar relative to increases in body mass. The second series of analyses described the growth pattern of the long bones of the appendicular skeleton. The allometric exponents seemed unremarkable compared to the few species described previously, and it was shown that the giraffe appendicular skeleton does not elongate in the dramatic way the neck does. Limbs at birth, after lengthening with positive allometry in utero, are already elongated and slender in shape and a further increase in the gracility of the bones is either not possible or not desirable. This result implies that it is neck elongation rather than leg elongation that is the dominant factor in the evolution of the giraffe shape. Nevertheless, the front limb bones and especially the humerus may show responsiveness to increasing high loads and/ or bending moments, which may be caused by the neck mass which increases with positive allometry, or with behaviours such as splaying the forelegs during drinking. In the third component of the study ontogenetic allometric equations in extant giraffes were applied to the remains of an extinct giraffid, G. sivalensis. The procedure was unusual as it employed ontogenetic regressions instead of the more commonly used interspecific regressions. The appropriateness of each equation to estimate body mass was evaluated by calculating the prediction error incurred in both extant giraffes and okapis (Okapia johnstoni). It was concluded that, due to body shape, ontogenetic equations were adequate and perhaps preferable to interspecific equations to estimate proportions in Giraffa species. This analysis showed that G sivalensis was smaller than extant giraffes and weighed around 400 kg (range 228 kg 575 kg), with a neck length of about 147 cm and a height of 390 cm. There may be evidence of sexual dimorphism in this species, with males being about twice the body weight of females. However, if sexual dimorphism was not present and all the bones were correctly attributed to this species, then G. sivalensis had a slender neck with a relatively stocky body. In conclusion, this study established ontogenetic regression equations for the skeleton of an animal of which the body shape seems to be at the extreme limits of mammalian possibility. The value of the current study lies especially in its sample size and quality, which included an unprecedented number of giraffe body masses, vertebral and long bone dimensions. This dataset had applications in the giraffe s evolutionary biology, palaeontology and even ecology. Future studies still need to compare the findings from giraffe growth with similar data from other taxa, especially those with long legs and necks. Specifically, it would interesting to determine if positively allometric neck growth combined with isometric leg growth is found in other mammalian species. In addition, the strength of giraffe long bones and vertebrae needs to be investigated with more accuracy using parameters like second moment of area. Lastly, further palaeontological studies on other giraffid sizes are necessary to validate the current and future interpretations of fossil giraffid findings.
Thesis (PhD)--University of Pretoria, 2015.
tm2016
Production Animal Studies
PhD

The giraffe at Nyaru were found to be browsers who made little use of graze during the study period. They utilized a diversity of 20 browse species. Two species, Acacia karroo and Acacia cyclops, formed the bulk of the giraffe diet throughout the year. A definite seasonal dietary shift was evident. A. karroo was favoured in summer and autumn and formed the main food species in spring, summer and autumn. A. cyclops was favoured throughout the study, but its contribution to the diet increased during winter when less A. karroo was consumed. This seasonal shift is related to the deciduous nature of Acacia karroo. Although a seasonal shift in species contribution to giraffe diet has been observed in many other giraffe feeding studies, no studies on giraffe feeding have been done in the Mosaic Thicket of the southern Cape. The ecological browsing capacity for giraffe in thicket was estimated to be between 0.020 BU/ha and 0.095 BU/ha. The browsing capacity for giraffe at Nyaru, based on the available phytomass 2–5 m above the ground, was estimated using those species that formed the bulk of the giraffe diet, and amounted to 0.063 BU/ha. A maximum of three giraffe could thus be stocked on the 157 ha of suitable giraffe habitat on Nyaru. This stocking rate recommendation lies within the range commonly recommended by local consultants for giraffe introductions into the southern Cape. Their recommendations are, however, not based on quantitative assessments such as performed in this study. The recommendation of this study should not be applied as a fixed ecological capacity for giraffe in thicket, but should be seen as a starting point in the adaptive management cycle. Ongoing monitoring of parameters, such as herbaceous composition and phytomass; as well as the condition of key browse species, is strongly advocated. A. karroo was browsed significantly more and carried significantly fewer pods per tree at a heavily used site compared to a lightly used site. Heavy browsing thus appears to affect the reproductive success of A. karroo significantly. Fewer pods are likely to lead to lower regeneration and thus reduced density of A. karroo. Whether A. karroo will maintain its dominance within the thicket vii community in the long run will be related to how individual plants survive and reproduce and if some can escape from herbivory. Fewer G. occidentalis were clumped with other species at the heavily used site compared to the lightly used site. This could possibly be attributed to the fact that intense browsing pressure at the heavily used site caused protective clumps to be eaten away, thus exposing G. occidentalis to higher ungulate browsing. Previous studies have found that nurse shrubs protect G. occidentalis against ungulate browsing. G. occidentalis was browsed significantly more at the heavily used site compared to the lightly used site. There was a general trend of fewer fruits at the heavily used site compared to the lightly used site, while fruits were absent on G. occidentalis growing alone at the heavily used site. This suggests a negative effect of heavy browsing on plant reproductive success and emphasizes the importance of nurse plants for the successful recruitment and hence long term prevalence of G. occidentalis in Mosaic Thicket.

Apart from its slender appearance, four main factors lead to questions regarding the bone density, mineral content and morphology of the giraffe skeleton: X A rapid vertical growth rate ¡V especially in the neck and metapodials X Biomechanical considerations pertaining to the tall and slender shape of the skeleton X A proportionally larger skeleton in relation to body mass X A seemingly abnormal mineral balance in their diet with possible signs of mineral deficiency (i.e. osteophagia) In this study the skeleton of the giraffe was compared with that of the African buffalo with regards to bone density, skeletal calcium (Ca) and phosphorus (P) content and certain femoral and metacarpal morphological characteristics. The aim was to establish if, compared to buffalo, the features of the giraffe skeleton differed in any unique way. Fourteen similar bones or parts of bones were collected from carcasses of six adult giraffe bulls and nine adult buffalo bulls. These bones were cleaned, weighed and their volume determined through water displacement, from which their density could be calculated. Hereafter, Ca and P content were analysed in 10 bones from each carcass. Morphological characteristics of cross-sections from femoral and metacarpal shafts were also measured. No significant differences between the density or mineral content of bones in the two species could be found. In both species 19,5% Ca and 9,5% P were measured in defatted bone. Although similar in mineral concentration, the giraffe skeleton contains three times more absolute Ca and P, which translates into a 1,5-2-fold higher dietary requirement for these minerals compared to buffaloes. A gradation in the volume and weight of cervical vertebrae was also seen in giraffes. This could hold biomechanical advantage for the carriage and manoeuvrability of the long neck. Bone wall thickness of the giraffe femur and metacarpus is increased compared to buffaloes. This could hold biomechanical advantage for the slender legs that are subjected to increased vertical forces. Adequate Ca seems to be acquired through very specific browse selection, which seems to be of evolutionary origin, while the acquisition of adequate P seems to be critical and a possible cause for osteophagia. This study is the first of its kind in these species and therefore also provide valuable baseline data for future work in this field.
Dissertation (MSc (Veterinary Science))--University of Pretoria, 2004.
Production Animal Studies
unrestricted

This thesis examines the subspecific taxonomic status of the giraffe and considers the role of formal taxonomy in the formulation of conservation policy. Where species show consistent. geographically structured phenotypic variation such geographic patterns may indicate selective forces (or other population-level effects) acting . upon local populations. These consistent geographic patterns may be recognised formally as subspecies and may be of interest in single or multi-species biodiversity or biogeography studies for delimiting areas of conservation priority. Subspecies may also be used in the formulation of management policies and legislation. Subspecies are, by definition, allopatric. This thesis explicitly uses methodology of systematic biology and phylogenetic reconstruction to investigate patterns of variation between geographic groups. The taxonomic status of the giraffe is apposite for review. The species provides three independent data sets that may be analysed quantitatively for geographic structure; pelage patterns, morphology and genetics. Museum specimens. grouped according to geographic origin, were favoured for study as more than one type of data was often available for an individual. Population aggregation analysis of forty pelage pattern characters maintained six separate subspecies, while agglomerating some neighbouring populations into a subspecies. A 'traditional' morphometric approach, using multivariate statistical analysis of adult skull measurements, was complemented by a geometric morphometric approach; landmarkrestricted eigenshape analysis. Four morphologically distinct groups were recognised by both morphological analyses. Phylogenetic analysis of mitochondrial DNA control region sequences indicates five major cIades. Nested cIade analysis identifies population fragmentation, range expansion and genetic isolation by distance as contributing to the genetic structure of the giraffe. The results of the analyses show remarkable congruence. These results are discussed in terms of the formulation of conservation policy and the differing requirements of'blological and legal classification systems. The value of a formal taxonomic framework to the recognition, and subsequent conservation, of biodiversity is emphasised.

Da die afrikanischen Spitzmaulnashörner in ihrer Heimat vom Aussterben bedroht sind, besitzt ihre Nachzucht in Zoologischen Gärten große Bedeutung. Zwar sind die Bestände der Giraffen in der Wildnis noch nicht besonders gefährdet, die Verlustrate dieser empfindlichen Tierart in menschlicher Obhut ist jedoch zu hoch. Die Gestagen-konzentrationen im Kot wurden bestimmt, um detailliertere Kenntnisse der Fortpflan-zungsphysiologie dieser beiden Spezies, die für eine erfolgreiche Reproduktion notwendig sind, zu erlangen. Die nichtinvasive Methode erwies sich als geeignet zur Überwachung der Fortpflanzung sowohl bei den Giraffen als auch den Spitzmaulnas-hörnern. Die Gestagenbestimmung im Kot erfolgte in 3 Schritten: Einwiegen des Kotes, Extraktion der Gestagene mit Hilfe von Methanol und ihre Bestimmung mittels Radioimmunoassay. Im methodischen Teil der Arbeit ergaben sich innerhalb einer Tierart (Giraffen, Spitzmaulnashorn und zusätzlich Damagazellen) nur geringfügige Schwankungen der Trockenmasse des Kotes von maximal 5 %, so dass sich auch bei unterschiedlichem Wassergehalt des Kotes ohne vorherige Trocknung der Proben gut vergleichbare Gestagenwerte in verschiedenen Kotproben der gleichen Tierart ermitteln lassen. Nach 24- bzw. 48-stündiger Lagerung bei Raumtemperatur waren im Kot von Giraffen und Nashörnern die Gestagenwerte im Vergleich zum sofortigen Einfrieren der Proben signifikant erhöht. Bei Nashörnern und Gazellen wurden nach längerer Lagerzeit (1 und 3 Monate) bei – 20 °C keine signifikanten Veränderungen der niedrigen Gestagen-konzentrationen im Kot festgestellt. Im Gegensatz dazu zeigte sich bei Kotproben von Giraffen mit hohen Ausgangskonzentrationen eine signifikante Erniedrigung (durchschnittlich 45 %). Im Vergleich zu einmaligem führte mehrmaliges Auftauen der Proben zum signifikanten Absinken der Gestagenkonzentrationen im Kot von Spitzmaulnashörnern und Gazellen. Im Ergebnis dieser Voruntersuchungen wurde für das weitere Vorgehen eine standardisierte Behandlung der Kotproben bis zur Bestimmung ihrer Gestagenkonzentrationen eingehalten. Bei 13 Giraffen und 8 östlichen Spitzmaulnashörnern aus 7 deutschen Zoos (insgesamt 2618 Kotproben) erfolgte zwischen 1997 und 2002 eine Zyklus- und/ oder Graviditäts-diagnostik mittels Gestagenbestimmungen im Kot. Dabei zeigten die Konzentrationen an Progesteronmetaboliten im Kot von 6 adulten, ingraviden Giraffen zyklische Schwankungen mit einer Zykluslänge von ca. 14 Tagen. Die Follikelphase dauerte im Mittel 6,9 Tage mit Gestagengehalten von durchschnittlich 259 ± 49 ng/g Kot und die Lutealphase hatte eine Länge von im Mittel 7,6 Tagen bei Konzentrationen an Progesteronmetaboliten von durchschnittlich 1163 ± 223 ng/g Kot. Brunstsymptome und/ oder Paarungen fielen immer mit dem Ende der Lutealphase zusammen. Am Beginn von 8 Graviditäten kam es bei den Giraffen zum Anstieg der Hormonkonzen-trationen auf Werte, die auch während der Lutealphase erreicht werden. Danach blieb die Gestagenausscheidung mit dem Kot zwischen der 58. und 1. Woche a. p. auf hohem Niveau. Eine Rückkehr auf Basalwerte, die während der Follikelphase auftreten, erfolgte erst 3 Tage p. p. Nach der Geburt konnten bei einigen Tieren postpartale Östren mit einer kurzfristigen Erhöhung der Hormonausscheidung im Kot festgestellt werden. Bei 7 adulten, ingraviden Spitzmaulnashörnern konnte mit der angewandten Methode kein Sexualzyklus ermittelt werden. Diese Tiere zeigten nur geringe Schwankungen der Gestagenausscheidung auf niedrigem Niveau (im Mittel 74 ± 18 ng/g Kot). Im Rahmen von 4 Graviditäten kam es bei den Spitzmaulnashörnern zunächst zu einer langsamen Erhöhung der Ausscheidung von Progesteronmetaboliten mit dem Kot, gefolgt von einem starken Anstieg ab der 56. Woche a. p. auf maximale Konzentrationen von ca. 674 ng/g Kot zwischen der 40. und 36. Woche a. p. Im weiteren Verlauf der Gravidität schwankten die Gestagengehalte zwischen 450-600 ng/g Kot. Eine Rückkehr auf das Niveau der Gestagenausscheidung von ingraviden Tieren war erst 3 Tage p. p. zu verzeichnen. Durch Festlegung eines Schwellenwertes von 200 ng/g Kot konnte eine Graviditätsdiagnose bei den Spitzmaulnashörnern ab etwa 52 Wochen vor der Geburt erfolgen. Eine Vorhersage des Geburtszeitpunktes war durch die Bestimmung der Gestagene im Kot weder bei Giraffen noch bei Spitzmaulnashörnern möglich
Since the African black rhinoceros is threatened to become extinct in its homeland, its offspring in zoological gardens possesses great importance. The existence of the giraffe is not yet particularly endangered in the wild, the loss of this sensible species in captivity is however very high. Gestagen concentrations in the faeces were determined in order to get more knowledge on the reproduction physiology of these two species, which is necessary for a successful reproduction. These non-invasive method was shown to be suitable for monitoring of the reproduction both in giraffes and black rhinoceroses. The gestagens in the faeces were analyzed in 3 steps: weighing of faeces specimens, gestagen extraction with methanol and their determination by means of radioimmunoassay. In the methodical part of the study the dry mass of the faeces showed only small variations up to 5 % within one species (Baringo giraffe, black rhinoceros and also dama gazelle). Thus, it was possible to estimate comparable gestagen levels from several faecal samples within one species without drying, in spite of their different amounts of water. After storage at room temperature for about 24 and/ or 48 hours gestagen concentrations in the faeces of giraffes and rhinoceroses were significantly increased in comparison to samples frozen immediately. After prolonged storage time (1 and 3 months) at – 20 °C no significant changes of low gestagen concentrations were stated in the faeces of rhinoceroses and gazelles. In opposite to this, in the faeces of giraffes with high initial gestagen concentrations a significant decrease (average 45 %) was evident. Repeated thawings of the samples led to a significant dropping of the gestagen levels in the faeces of rhinoceroses and gazelles compared to single thawing. As a result of these preceding investigations a standardized treatment of the faeces samples prior to determination of their gestagen concentrations was observed. Control of reproduction cycle and pregnancy respectively by means of faecal gestagen monitoring was carried out in a total of 2618 faecal samples of 13 giraffes and 8 eastern black rhinoceroses, collected in 7 German zoos from 1997 to 2002. Concentrations of progesterone metabolites in the faeces of 6 adult, nonpregnant giraffes showed cyclic fluctuations with a cycle length of approximately 14 days. The follicular phase took 6.9 days on an average with a mean gestagen concentration of 259 ± 49 ng/g faeces and the luteal phase had a length of 7.6 days on an average with a mean concentration of 1163 ± 223 ng/g faeces. Oestrus behaviour and/ or mating was observed always at the end of the luteal phase. A rise of hormone concentrations to a level, which is characteristic for the luteal phase, was evident at the beginning of 8 pregnancies in giraffes. Afterwards the excretion of faecal gestagens remained on a high level between week 58th and 1st a. p. Basal values, which are characteristic for the follicular phase, were detected 3 days p. p. After parturition some animals showed oestrus behaviour with a short increase of hormone excretion by the faeces. In 7 adult, nonpregnant black rhinoceroses no reproduction cycle could be ascertained by determination of gestagens in the faeces. Only small fluctuations of the gestagen excretion on a low level (on an average 74 ± 18 ng/g faeces) were evident in these animals. Within 4 pregnancies of black rhinoceroses a slow increase of the excretion of faecal progesterone metabolites could be detected, followed by a massive rise from week 56th a. p. to maximum concentrations of approximately 674 ng/g faeces between week 40th and 36th a. p. In the ongoing pregnancy the gestagen concentrations varied between 450-600 ng/g faeces. A return to the level of the gestagen excretion of nonpregnant animals was noticed 3 days p. p. Diagnosis of pregnancy of black rhinoceroses was possible approximately 52 weeks prior to parturition by defining a threshold value of 200 ng/g faeces. Prediction of the day of delivery by means of gestagen determination in the faeces was neither possible in giraffes nor in black rhinoceroses

The giraffe (Giraffa camelopardalis) occupies a variety of habitats across sub- Saharan Africa. It is characterised by a loose social organisation, and a dominancedriven polygynous mating system. This project sought to explain biogeographic and inter-sexual variation in pelage colouration in the context of natural and sexual selection. I also sought to test the hypothesis that in a semi-arid environment, limited resources (food and water) would predictably concentrate females, increasing the potential for dominant males to monopolise matings. I analysed photos from across Africa, and reveal that where yearly bright sunshine is greater, female giraffe in particular tend to be lighter, resulting in sexual dichromatism in high insolarity locations. I hypothesised that dark pelage colour is maintained in males through sexual selection for a costly status signal. Field work was carried out in Etosha NP, Namibia. Using photographic records, I identified 431 individual giraffe. I surveyed the study area regularly and collected data on group composition and behaviour upon locating giraffe. I carried out focal watches, and recorded all observations of agonistic and mating behaviour. Darker males tended to be older and more dominant than lighter males, associated less with females, but had greater success in courting females. Food and water affected female movements on both a spatial and temporal scale. At waterholes, encounter rates were increased and consequently mating and agonistic interactions more frequent. Paler males had a greater chance of interacting with females at waterholes because of higher intruder pressure, but when present, darker males always monopolised courtship opportunities. Mature males demonstrated a diversity of ranging strategies that affected association with females. These individual differences are assumed to relate to status and probably affect individual reproductive success. Evidence suggests male reproductive success is skewed towards mature dark males, but may also vary among dark males, with some potentially being excluded from mating.

An increasing number of species are declining in the wild. Giraffes have suffered an estimated 36-40% decline in the past ten years and are now listed as Vulnerable on the IUCN Red List of Threatened Species (Muller, 2016). Given this rate of decline, there is an urgent need for the development of conservation plans and practices for giraffes. However, giraffes have been understudied in relation to other large African mammals and even basic aspects of their behaviour and ecology are still unknown or misunderstood. Understanding a species’ social organisation and behaviour is critical to developing suitable conservation and management plans. In this thesis I provide a thorough investigation of giraffe social behaviour and the factors which influence association patterns and discuss how these may be related to fitness and impact upon the survival of the species. My results show that giraffes live in complex social systems which are composed of non-random associations, the patterns of which are influenced by age and sex of individual, behavioural state, reproductive state, and environmental factors such as disturbance and habitat structure. My results have contributed knowledge to understanding the complex social behaviour of giraffes and have demonstrated how generic conclusions about the behaviour of a species should not be drawn from studies of single populations. My study provides an important starting point from which to develop the comparative study of networks and determine the relative influence of environmental factors on network structure and provides comprehensive information that can be used for the management of giraffe populations in the wild.

Although there are many studies on mammalian bone histology, there are only a few that have examined the bone histology of artiodactyls, or focused specifically on osteohistological changes during ontogeny. The current study investigates the microanatomy and histology of giraffe limb bones through ontogeny. Mid-diaphyseal sections of humeri, radii, metacarpals, femora, and tibiae of 14 individuals representing individuals of known sex, as well as at different ontogenetic stages (foetal, juveniles, subadults, and adults). Thin sections were prepared for all the bones, and microanatomical (using Bone Profiler) and histological analyses were conducted on each of the sections. The study examined three main aspects, 1) Crosssectional shape changes in limb bones through ontogeny, 2) Histological changes through ontogeny in each of the limb bones, and 3) Histovariability among skeletons. The results of the study show that the foetus and juvenile individuals have round cross-sections, with small vacant medullary cavities, while cross sections of older individuals tend to be oval with variable amounts of cancellous bone surrounding the medullary cavity. The highest bone compactness values were obtained for the humerus and femur of the foetus, whereas the radius, metacarpal, and tibia bone compactness values are similar across the age classes. In terms of histology, this study found that the earlier ontogenetic stages had highly vascularised fibrolamellar bone in their cortices, which contrasts with that of the subadults and adults where more slowly deposited bone tissue occurs. These observations indicate that after rapid initial growth during early ontogeny, osteogenesis (and overall growth) slows down. This research also documents the fusion of the metacarpal III and IV, and the associated changes that occur in the histology. The study also highlights that the tibia is the only bone that has long radial vascular canals in the cortex. Overall the results of this study have provided a much better understanding of the bone histology of giraffes during ontogeny and has therefore filled an important gap in our knowledge of mammalian bone tissues. Furthermore, this study has direct implications for any future palaeohistological studies of fossil giraffids from Langebaanweg in South Africa.

Allomaternal care is one of the most interesting types of cooperation among females. Its most extreme form is allonursing, nursing of a non-filial young, which is still not completely understood, even though many hypotheses have been postulated. This type of cooperation among giraffes had not been expected for long time. This was based on the initial opinion that giraffes do not have social system and form only weak social bonds. However, my bachelor and master theses showed high occurrence of allonursing in captive giraffes. The first aim (1) of this thesis was to test all possible hypotheses explaining allonursing in captive giraffes. However, a lot of the information needed to test them were missing, which resulted in the formulation of further aims. The second aim (2) was to test the hierarchy in captive giraffes. The third aim (3) was to describe the growth and weight of captive giraffes. The fourth aim (4) was to compare nursing patterns in the zoo and in the nature reserve Bandia, Senegal and the last aim (5) was to test the social bonds among giraffes in the nature reserve Bandia, Senegal. (1) From 2007 to 2011, the nursing behaviour of 24 females and 37 calves was observed. Eighty-three percent of the females allonursed a nonfilial calf and 86.5% of calves allosuckled from a nonmaternal female. Allonursing in giraffes was explained by milk-theft from the point of view of the calves and possible reciprocity among females. (2) The agonistic interactions of 31 giraffes were recorded in four herds. A linear hierarchy was been found among giraffes and rank was significantly affected by age and time spent in the herd. (3) The weight data from 43 giraffes in Prague zoo were collected from 2009 to 2013 and provided the basic information about giraffe growth and weight. (4) I also observed the nursing behaviour of seven and four female-calf pairs in the fenced Bandia reserve, Senegal, and in Prague zoo, respectively, both for 22 days. The differences in nursing patterns were likely to reflect anti-predator behaviour, the population density of animals and the distribution of food resources. (5) Finally, I investigated the social preferences of 28 introduced giraffes in semi-captivity in the nature reserve Bandia, Senegal and provided the results supporting the existence of a fission fusion social system among giraffes with social preferences among adult females. The overall results provide unique findings on allonursing in general as well as changing our perspective on giraffe social behaviour.

With an increase in the popularity of wildlife ranching in southern Africa has come the introduction of non-native (extralimital) mammalian herbivores. Financial gain has arguably been at the forefront of these introductions, with little or no assessment of the ecological consequences. The diet of three populations of introduced giraffe Giraffa camelopardalis was assessed by direct observation in the Eastern Cape Province, South Africa between January 2002 and October 2003, as the first step towards understanding the ecological role played by giraffe in the region. Similar to the diet of giraffe within their native range, a deciduous species from the genus Acacia (Acacia karroo) was the most important species in the diet. Giraffe in the Eastern Cape Province, however, consumed more evergreen species than those within their native range. The relative lack of deciduous species in the Eastern Cape Province provides a probable explanation for such a result. Seasonal variation in the consumption of the most important species in the diet was evident with members of the genus Rhus being more important in the winter months. This was attributed to the deciduous nature of A. karroo. The potential for giraffe to have a detrimental effect on the indigenous vegetation is discussed. We conclude that the study provides a much-needed list of plant species threatened by giraffe browsing in a region where the vegetation is thought to have evolved in the absence of such a browser.

My master's thesis deals with monitoring of giraffes group (mainly three members - male Johan, cow Berta and young cow Laura) in Prague zoological garden in the period from summer 2012 till spring 2013. Behavior of three chosen individuals is presented in the form of graphs and charts for better clarity. Overview of all Giraffidae Family, its description and living area, is included in the thesis. Zoological gardens breeding giraffes and conditions of their breed are included in this project.

Giraffe (Giraffa camelopardalis) are extralimital (non-native) to the Eastern Cape Province, South Africa yet they have and continue to be introduced to the region. Financial gain has arguably been the driving force behind these introductions as foreign tourists associate giraffe with Africa and the African wildlife experience. This raises a number of ethical, ecological and philosophical questions especially when it is considered that the impact of these browsers on the indigenous vegetation has remained largely unquantified. In this study I assessed the diet and potential impact of three populations of giraffe in the Eastern Cape Province between January 2002 and October 2003. The diet was assessed by both direct observations and faecal analysis. There was no significant difference (P > 0.05) between the results of the two methods of analysis, although direct observations appeared to be a superior method for assessing the diet of giraffe. The diet of giraffe in the Eastern Cape Province was similar to that within their native range with a deciduous species from the genus Acacia (Acacia karroo) being the most important component of the diet. However, giraffe in the Eastern Cape Province consumed more evergreen plant species than those within their native range. The relative lack of deciduous species in the Eastern Cape Province provides a likely explanation for such a result. Seasonal variation in the consumption of the most important species in the diet was evident and this was attributed to the deciduous nature of A. karroo and the seasonal growth of new shoots which were more palatable. The vegetation of the areas most commonly utilised by giraffe at each site was sampled using the point-centred-quarter method and the results related to the frequency of each species in the diet to calculate preference indices. Giraffe preference was strongest for A. karroo and this was attributed to the highly favourable chemical composition of the species. The browse utilisation of giraffe at each site was determined using the twig-length method and intake rates for the three most important species in the diet calculated using a pre-existing regression equation. Male giraffe fed at a higher rate than females. This was probably due to males adopting a “time-minimising” strategy to their feeding in order to allow more time for reproductive pursuits. Giraffe browse utilisation was highest where giraffe density was highest. However, several species were more heavily browsed than others even when giraffe density was low, suggesting that giraffe are capable of negatively affecting the indigenous flora of the province. I conclude that giraffe numbers should be reduced relative to property size in the Eastern Cape Province and that research into the impact of not only giraffe but the combined effects of giraffe and other extralimital herbivores on the indigenous flora and fauna be continued.

The current study uses the head and neck of giraffe (Giraffa camelopardalis) as a model for tracking the course of evolutionary change. Gould (2002) has argued that there are three main avenues of evolutionary change that result in the genesis of new morphologies. These are phylogenetic constraints, structural or allometric scaling laws of form, and specific unique adaptations. It is well known that the unique characteristic of the giraffe is its extremely long neck and yet, it only has seven cervical vertebrae. To study the neck the vertebral body lengths of different aged giraffes were measured to determine the contribution of the cervical vertebrae to the total vertebral column. The vertebrae of several extant ungulates as well as those of fossil giraffids were used as a comparison with the giraffe. CT scans were used on several giraffe skulls to study the extent of the frontal sinus in the giraffe in an attempt to explain why the giraffe evolved such a large frontal sinus. The vertebral columns and skulls of several ungulates, including the okapi (Okapia johnstoni) were also used to compare with the results obtained from the giraffe. Immunohistochemistry was used to study the medulla and spinal cord sections of the giraffe to determine if the location and size of the nuclei remained unchanged to the basic ungulate or mammalian plan in spite of the unusually long neck, or if this long neck led to changes in the nuclei found in those regions. The results of these stains were all compared to the published literature available. Although more studies need to be conducted on other ungulates to conclusively determine why giraffe have evolved a long neck, overall the results showed that the anatomy giraffe head and neck remained true to the basic mammalian plan, with very little changing in terms of it morphology. The giraffe brain and spinal cord also resembled that of a typical ungulate. This leads to the conclusion that constraints and allometric scaling laws of form play a greater role than previously thought in the evolution of extreme morphologies.

Da die afrikanischen Spitzmaulnashörner in ihrer Heimat vom Aussterben bedroht sind, besitzt ihre Nachzucht in Zoologischen Gärten große Bedeutung. Zwar sind die Bestände der Giraffen in der Wildnis noch nicht besonders gefährdet, die Verlustrate dieser empfindlichen Tierart in menschlicher Obhut ist jedoch zu hoch. Die Gestagen-konzentrationen im Kot wurden bestimmt, um detailliertere Kenntnisse der Fortpflan-zungsphysiologie dieser beiden Spezies, die für eine erfolgreiche Reproduktion notwendig sind, zu erlangen. Die nichtinvasive Methode erwies sich als geeignet zur Überwachung der Fortpflanzung sowohl bei den Giraffen als auch den Spitzmaulnas-hörnern. Die Gestagenbestimmung im Kot erfolgte in 3 Schritten: Einwiegen des Kotes, Extraktion der Gestagene mit Hilfe von Methanol und ihre Bestimmung mittels Radioimmunoassay. Im methodischen Teil der Arbeit ergaben sich innerhalb einer Tierart (Giraffen, Spitzmaulnashorn und zusätzlich Damagazellen) nur geringfügige Schwankungen der Trockenmasse des Kotes von maximal 5 %, so dass sich auch bei unterschiedlichem Wassergehalt des Kotes ohne vorherige Trocknung der Proben gut vergleichbare Gestagenwerte in verschiedenen Kotproben der gleichen Tierart ermitteln lassen. Nach 24- bzw. 48-stündiger Lagerung bei Raumtemperatur waren im Kot von Giraffen und Nashörnern die Gestagenwerte im Vergleich zum sofortigen Einfrieren der Proben signifikant erhöht. Bei Nashörnern und Gazellen wurden nach längerer Lagerzeit (1 und 3 Monate) bei – 20 °C keine signifikanten Veränderungen der niedrigen Gestagen-konzentrationen im Kot festgestellt. Im Gegensatz dazu zeigte sich bei Kotproben von Giraffen mit hohen Ausgangskonzentrationen eine signifikante Erniedrigung (durchschnittlich 45 %). Im Vergleich zu einmaligem führte mehrmaliges Auftauen der Proben zum signifikanten Absinken der Gestagenkonzentrationen im Kot von Spitzmaulnashörnern und Gazellen. Im Ergebnis dieser Voruntersuchungen wurde für das weitere Vorgehen eine standardisierte Behandlung der Kotproben bis zur Bestimmung ihrer Gestagenkonzentrationen eingehalten. Bei 13 Giraffen und 8 östlichen Spitzmaulnashörnern aus 7 deutschen Zoos (insgesamt 2618 Kotproben) erfolgte zwischen 1997 und 2002 eine Zyklus- und/ oder Graviditäts-diagnostik mittels Gestagenbestimmungen im Kot. Dabei zeigten die Konzentrationen an Progesteronmetaboliten im Kot von 6 adulten, ingraviden Giraffen zyklische Schwankungen mit einer Zykluslänge von ca. 14 Tagen. Die Follikelphase dauerte im Mittel 6,9 Tage mit Gestagengehalten von durchschnittlich 259 ± 49 ng/g Kot und die Lutealphase hatte eine Länge von im Mittel 7,6 Tagen bei Konzentrationen an Progesteronmetaboliten von durchschnittlich 1163 ± 223 ng/g Kot. Brunstsymptome und/ oder Paarungen fielen immer mit dem Ende der Lutealphase zusammen. Am Beginn von 8 Graviditäten kam es bei den Giraffen zum Anstieg der Hormonkonzen-trationen auf Werte, die auch während der Lutealphase erreicht werden. Danach blieb die Gestagenausscheidung mit dem Kot zwischen der 58. und 1. Woche a. p. auf hohem Niveau. Eine Rückkehr auf Basalwerte, die während der Follikelphase auftreten, erfolgte erst 3 Tage p. p. Nach der Geburt konnten bei einigen Tieren postpartale Östren mit einer kurzfristigen Erhöhung der Hormonausscheidung im Kot festgestellt werden. Bei 7 adulten, ingraviden Spitzmaulnashörnern konnte mit der angewandten Methode kein Sexualzyklus ermittelt werden. Diese Tiere zeigten nur geringe Schwankungen der Gestagenausscheidung auf niedrigem Niveau (im Mittel 74 ± 18 ng/g Kot). Im Rahmen von 4 Graviditäten kam es bei den Spitzmaulnashörnern zunächst zu einer langsamen Erhöhung der Ausscheidung von Progesteronmetaboliten mit dem Kot, gefolgt von einem starken Anstieg ab der 56. Woche a. p. auf maximale Konzentrationen von ca. 674 ng/g Kot zwischen der 40. und 36. Woche a. p. Im weiteren Verlauf der Gravidität schwankten die Gestagengehalte zwischen 450-600 ng/g Kot. Eine Rückkehr auf das Niveau der Gestagenausscheidung von ingraviden Tieren war erst 3 Tage p. p. zu verzeichnen. Durch Festlegung eines Schwellenwertes von 200 ng/g Kot konnte eine Graviditätsdiagnose bei den Spitzmaulnashörnern ab etwa 52 Wochen vor der Geburt erfolgen. Eine Vorhersage des Geburtszeitpunktes war durch die Bestimmung der Gestagene im Kot weder bei Giraffen noch bei Spitzmaulnashörnern möglich.
Since the African black rhinoceros is threatened to become extinct in its homeland, its offspring in zoological gardens possesses great importance. The existence of the giraffe is not yet particularly endangered in the wild, the loss of this sensible species in captivity is however very high. Gestagen concentrations in the faeces were determined in order to get more knowledge on the reproduction physiology of these two species, which is necessary for a successful reproduction. These non-invasive method was shown to be suitable for monitoring of the reproduction both in giraffes and black rhinoceroses. The gestagens in the faeces were analyzed in 3 steps: weighing of faeces specimens, gestagen extraction with methanol and their determination by means of radioimmunoassay. In the methodical part of the study the dry mass of the faeces showed only small variations up to 5 % within one species (Baringo giraffe, black rhinoceros and also dama gazelle). Thus, it was possible to estimate comparable gestagen levels from several faecal samples within one species without drying, in spite of their different amounts of water. After storage at room temperature for about 24 and/ or 48 hours gestagen concentrations in the faeces of giraffes and rhinoceroses were significantly increased in comparison to samples frozen immediately. After prolonged storage time (1 and 3 months) at – 20 °C no significant changes of low gestagen concentrations were stated in the faeces of rhinoceroses and gazelles. In opposite to this, in the faeces of giraffes with high initial gestagen concentrations a significant decrease (average 45 %) was evident. Repeated thawings of the samples led to a significant dropping of the gestagen levels in the faeces of rhinoceroses and gazelles compared to single thawing. As a result of these preceding investigations a standardized treatment of the faeces samples prior to determination of their gestagen concentrations was observed. Control of reproduction cycle and pregnancy respectively by means of faecal gestagen monitoring was carried out in a total of 2618 faecal samples of 13 giraffes and 8 eastern black rhinoceroses, collected in 7 German zoos from 1997 to 2002. Concentrations of progesterone metabolites in the faeces of 6 adult, nonpregnant giraffes showed cyclic fluctuations with a cycle length of approximately 14 days. The follicular phase took 6.9 days on an average with a mean gestagen concentration of 259 ± 49 ng/g faeces and the luteal phase had a length of 7.6 days on an average with a mean concentration of 1163 ± 223 ng/g faeces. Oestrus behaviour and/ or mating was observed always at the end of the luteal phase. A rise of hormone concentrations to a level, which is characteristic for the luteal phase, was evident at the beginning of 8 pregnancies in giraffes. Afterwards the excretion of faecal gestagens remained on a high level between week 58th and 1st a. p. Basal values, which are characteristic for the follicular phase, were detected 3 days p. p. After parturition some animals showed oestrus behaviour with a short increase of hormone excretion by the faeces. In 7 adult, nonpregnant black rhinoceroses no reproduction cycle could be ascertained by determination of gestagens in the faeces. Only small fluctuations of the gestagen excretion on a low level (on an average 74 ± 18 ng/g faeces) were evident in these animals. Within 4 pregnancies of black rhinoceroses a slow increase of the excretion of faecal progesterone metabolites could be detected, followed by a massive rise from week 56th a. p. to maximum concentrations of approximately 674 ng/g faeces between week 40th and 36th a. p. In the ongoing pregnancy the gestagen concentrations varied between 450-600 ng/g faeces. A return to the level of the gestagen excretion of nonpregnant animals was noticed 3 days p. p. Diagnosis of pregnancy of black rhinoceroses was possible approximately 52 weeks prior to parturition by defining a threshold value of 200 ng/g faeces. Prediction of the day of delivery by means of gestagen determination in the faeces was neither possible in giraffes nor in black rhinoceroses.

Habitat loss and fragmentation is a crisis affecting wildlife worldwide. In Tanzania, East Africa, a dramatic and recent (<80 years) expansion in human settlement and agriculture threatens to reduce gene flow among protected areas for many species of large mammals. Wildlife linkages can mitigate population isolation, but linkage designs lacking empirical justification may be controversial and ineffective. Connectivity conservation requires an understanding of how biogeographic factors shaped gene flow prior to habitat loss or fragmentation, however the history of interaction among populations is rarely known. The goal of my study was to provide context for connectivity conservation in central and southern Tanzania by identifying landscape features that have shaped gene flow for three ungulate species with different dispersal capabilities. I investigated historical patterns of connectivity for Maasai giraffe (Giraffa camelopardalis tippelskirchi), impala (Aepyceros melampus), and eland (Tragelaphus oryx) by estimating genetic structure among four to eight protected areas per species. Genetic structure changes very slowly among large populations and thus is likely to reflect historical processes instead of recent anthropogenic influences. I collected noninvasive DNA samples and generated microsatellite genotypes at 8 to 15 loci per species, then estimated genetic diversity metrics (allelic richness, AR, and expected heterozygosity, H[subscript E]) for each population (defined by reserve). I also calculated genetic distance (F[subscript ST] and Nei's unbiased genetic distance, D[subscript hat]) and an estimate of gene flow (Nm) between all population pairs for each species. To elucidate the possible causes of genetic structure between these populations, I tested for isolation by distance and isolation by resistance based on a suite of biogeographic factors hypothesized to affect gene flow. To do this, I created GIS-based resistance surfaces that assigned different costs of movement to landscape features. I created one or more resistance surfaces for each hypothesis of landscape effect. I used circuit theory to estimate the cumulative resistance between each pair of reserves for each weighting scheme, and then performed Mantel tests to calculate the correlation between these resistances and the observed population pairwise genetic distances (D[subscript hat]). I chose the optimal resistance model for each species as the model that was most highly correlated with observed genetic patterns. To verify that the correlation of resistance models with genetic distance was not an artefact of geographic distance, I performed partial Mantel tests to calculate correlation while controlling for the effect of geographic distance. Finally, I compared historical gene flow patterns to the distribution of contemporary human activity to predict areas that are at risk of a loss of connectivity. Indices of genetic diversity were moderate for all three species and comparable to previously reported values for other savannah ungulates. Diversity (both H[subscript E] and A[subscript R]) was highest in eland and lowest in giraffe for these populations, and was not consistently correlated with reserve size as has been reported for other species in East Africa. Although patterns in genetic distance were broadly similar across all three species there were also striking differences in connectivity, highlighting the importance of cross-species comparisons in connectivity conservation. At this scale, resistance models based on slope strongly predicted population structure for all three species; distance to water was also highly correlated with genetic distance in eland. For all three species, the greatest genetic distances occurred between populations separated by the Eastern Arc Mountains, suggesting that the topography of this area has long acted as a barrier to gene flow, but this effect is present in varying degrees for each species. I observed high levels of historical gene flow between centrally located populations (Ruaha National Park and Rungwa Game Reserve) and those in the southwest (Katavi National Park and Rukwa Game Reserve). Although human settlement in this area has been low relative to other areas, the connection between the Katavi/Rukwa and Ruaha ecosystems may be threatened by increased human activity and warrants conservation. High levels of historical gene flow were also seen between reserves in the northeast (Tarangire National Park, Swagaswaga Game Reserve) and the central and southwest populations. These connections appear highly threatened due to current land use practices, and may have already suffered a loss of gene flow. Field surveys in the lands surrounding the northeastern reserves are needed to quantify current levels of connectivity and determine whether corridors could be established to maintain or restore gene flow with other reserves.
Graduation date: 2012

À une période où les contacts entre humains et animaux sauvages augmentent régulièrement, il est nécessaire de comprendre les conséquences de ces interactions sur l'écologie des populations animales, que ce soit à court ou à long terme. Les perturbations sont de nature diverse et leurs impacts le sont tout autant. La variation dans la réponse des individus peut avoir des répercussions sur leur distribution, leur utilisation de l'habitat, leur reproduction et ultimement leur survie. Cette variation peut être causée par des facteurs environnementaux, mais également par des traits intrinsèques aux individus (ex.: qui démontrent des différences constantes à travers le temps entre les individus (indices de tempérament)). Quelques études récentes laissent supposer que certains traits de comportement en relation avec la tolérance des animaux humains pourraient expliquer une distribution spatiale non aléatoire des individus dans un habitat présentant une variation des perturbations anthropiques. Dans le but de vérifier cette hypothèse, nous avons utilisé la distance de fuite (FID), qui est utilisée en biologie de la conservation pour évaluer l'impact de la présence humaine sur les populations d'animaux sauvages. Nous avons évalué si les individus montraient des différences constantes de FID à travers le temps, à l'aide de mesures répétées en 2006 (160 observations sur 88 individus) et 2008 (84 observations sur 65 individus), dans la dernière population de girafes de l'Afrique de l'Ouest (Giraffa camelopardalis peralta) localisée au Niger. La distance de fuite variait selon le sexe, l'âge et la distance d'alerte des individus. De plus, les individus montraient des différences de FID permanentes, la répétabilité étant supérieure à l'intérieur de la même année (r = 0.45 en 2006, r = 0.43 en 2008) que lorsque les données étaient rassemblées sur les deux années (r = 0.22). Nous avons ensuite utilisé la distance de fuite moyenne pour chaque individu (FIDm) comme indice de tempérament (de peur) pour expliquer la distribution des girafes en relation avec la présence humaine. Nous avons utilisé les coordonnées GPS (en incluant les données de recensement des années 2007, 2008 et 2009) pour mesurer les distances entre la localisation des groupes de girafes et 1) la route la plus proche (incluant la route goudronnée principale et les routes secondaires faites de latérites), 2) la route goudronnée principale, 3) le village le plus proche. Ces distances sont utilisées ici comme des indices du niveau de perturbation par les humains. La distance de fuite moyenne individuelle (FIDm) de l'année 2006, était positivement associée à ces trois distances chez les femelles. D'autres facteurs comme la présence de jeunes dans le groupe et la taille du groupe semblent également affecter leur distribution. Nos résultats supportent l'hypothèse selon laquelle les individus ayant une plus ou moins forte tolérance aux humains diffèrent dans leur probabilité d'être observés près de zones à forte affluence humaine. Ces résultats pourraient avoir des implications importantes tant pour l'écologie que la conservation des populations animales, spécialement dans un contexte où les perturbations anthropiques mondiales sont en croissance. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Giraffa camelopardalis peralta, distance de fuite, constance, variation inter-individuelle, distribution, perturbation, présence humaine.

Orientação: Daniel Murta; co-orientação: Nuno Siqueira
A espécie de girafa (Giraffa camelopardalis) atualmente está classificada como vulnerável em estado selvagem pela lista vermelha de espécies ameaçadas da IUCN (União Internacional para a Conservação da Natureza). A sua documentação a nível reprodutivo e a saúde dos seus neonatos em cativeiro assume, cada vez mais, um papel indispensável no esforço de salvar esta espécie e as suas subespécies de vias de extinção ganhando ainda um relevo mais preponderante visto que o primeiro mês de vida é o mais crítico em neonatos que nascem em cativeiro. Este estudo descreve e compara o crescimento de dois neonatos de girafa de Rothschild (n=2) durante sessenta dias, cerca de nove semanas, em cativeiro, discutindo os resultados com base na bibliografia existente. Neste estudo um dos neonatos foi criado à mão com sucesso, tendo sido rejeitado pela progenitora, enquanto que o outro foi criado pela mesma progenitora. Em ambos os casos foi feito o registo quer do número de amamentações por dia, quer da duração das mesmas, da evolução do peso individual e do seu desenvolvimento em termos de crescimento em altura. O número médio de amamentações por dia variou, indo de 3 para 5 e de 11 para 3 respectivamente ao longo do período de sessenta dias e a respetiva duração da amamentação diminuiu. Por cada amamentação esta variou no primeiro neonato de 3 minutos e 35 segundos para 2 minutos no final das nove semanas, enquanto no segundo neonato baixou de 1 minuto e 50 segundos para 1 minuto e 41 segundos. A evolução do peso foi de 847 g/dia e de 1225 g/dia do nascimento até aos sessenta dias de vida em cada um dos animais. O neonato criado à mão cresceu 45 centímetros e, no caso do neonato criado pela progenitora o seu crescimento foi de 49 centímetros, ambos no mesmo período de sessenta dias. Quer os métodos utilizados durante o período de amamentação do neonato rejeitado pela progenitora, quer os métodos naturais utilizados na progenitora antes do nascimento e após o nascimento do neonato, revelaram-se eficazes na criação das condições necessárias à sua sobrevivência.
Abstract The giraffe species (Giraffa camelopardalis) is currently classified as vulnerable in the wild by the IUCN (International Union for Conservation of Nature) Red List of Threatened Species. Their reproductive documentation and the health of their captives newborns increasingly assume an indispensable role in the effort to save this species and its subspecies from extinction, gaining even more importance since the first month of life it is the most critical in neonates who are born in captivity. This study describes and compares the growth of two newborns of Rothschild’s giraffe (n=2) during sixty days, about nine weeks, in captivity, discussing the findings based on the existing bibliography. In this study, one of the newborns was successfully created by hand, being rejected by the mother, while the other one was created by the same mother. In both cases, the number of breastfeeding per day, the durations of breastfeeding, the evolution of individual weight and their development in terms of height growth were recorded. The average number of breastfeeding per day varied, ranging from 3 to 5 and from 11 to 3 respectively over the sixty-day period and the respective duration of breastfeeding decreased. For each breastfeeding, this varied in the first newborn from 3 minutes and 35 seconds to 2 minutes at the end of ninth weeks, while in the second newborn it dropped by 1 minutes and 50 seconds to 1 minutes and 41 seconds. The weight evolution was 847 g/day and 1225 g/day from birth to sixty days of life in each animal. The newborn created by hand grew 45 centimeters and, in the case of the newborn created by the mother, its growth was 49 centimeters, both in the same period of sixty day. Both the methods used during the breastfeeding period of the newborn rejected by the mother and the natural methods used in the mother before birth and after the birth of the newborn, proved to be effective in creating the conditions necessary for their survival.

Les girafes vivent dans un système social que l'on dit caractérisé par la fission-fusion aléatoire des groupes d'individus. Ce n'est que récemment que nous avons eu recours à l'analyse des réseaux sociaux (ARS) pour étudier les structures sociales chez ces sociétés fluides. Dans cette étude, nous utilisons l'ARS afin de déterminer si les girafes de la dernière population vivant en liberté en Afrique de l'Ouest, Giraffa camelopardalis peralta, s'associent de manière aléatoire et, dans le cas où il ne s'agit pas d'associations aléatoires, nous tentons de déterminer quels facteurs entrent en jeu. De plus, au cours des 20 dernières années, ces girafes ont été soumises à de nouvelles conditions sur le plan écologique : moins de pression de la part des prédateurs, augmentation de la densité des populations (des girafes ainsi qu'humaine) et diminution de leur habitat. Nous examinons donc, dans un premier temps, quelles ont été les conséquences de ces facteurs sur la structure sociale de ces ongulés en comparant les réseaux sociaux de deux périodes où les conditions différaient (1996-1998 vs 2006-2009). De plus, nous vérifions, à l'aide des caractéristiques individuelles issues de chaque réseau, si certains individus ont des positions centrales et jouent donc un rôle social dans leur réseau. Finalement, pour les individus qui se trouvaient dans les deux périodes d'étude, nous examinons si leur position au sein du réseau a changé avec le temps. Au cours de ces deux périodes, nous avons trouvé que les écarts-types des indices d'associations des deux réseaux étaient plus élevés que ceux des réseaux où les associations étaient distribuées aléatoirement. Dans les deux réseaux, le sexe des individus jouait un rôle dans l'établissement des associations; il y avait un plus grand nombre d'associations d'individus de même sexe que de sexe opposé. Contrairement à nos attentes, ce sont surtout les mâles adultes qui démontraient de fortes associations préférentielles entre eux alors que les femelles accompagnées de girafons avaient tendance à s'éviter, et ce, dans les deux réseaux. Les classes d'âge ne semblent pas affecter les forces d'association dans cette population sauf chez les femelles de classes d'âges différentes (adultes et juvéniles) dans le premier réseau, ce qui semblerait être causé par le lien mère-jeune. Ainsi, ces liens entre la mère et son girafon étaient plus forts dans le réseau de la période 1996-1998 comparé à ceux qui existaient chez les individus du réseau 2006-2009. En effet, malgré le peu de données sur l'apparentement des individus nous avons constaté une relation positive entre les forces d'association et le degré d'apparentement des individus. Toutefois, cette corrélation était plus forte dans le réseau 1996-1998. Finalement, les caractéristiques individuelles variaient très peu à l'intérieur d'un réseau laissant croire qu'aucun individu ou type d'individu n'occupe un rôle central dans cette population. De plus, nous n'avons noté aucun changement au niveau des caractéristiques des individus entre les deux réseaux, ce qui nous permet de dire que les individus, même s'ils étaient plus âgés en 2006-2009, ne devenaient pas moins sociables ni qu'ils occupaient la même position. On peut conclure, que malgré leur système social fluide de fission-fusion, les girafes ne s'associent pas de façon aléatoire et qu'en dépit de l'augmentation de la population et de la diminution de l'habitat, la structure sociale observée aux deux époques montre des caractéristiques très semblables. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : réseaux sociaux, grégarisme, disponibilité de l'habitat, densité de population, Giraffa camelopardalis peralta