Predicting the buoyancy, equilibrium and potential swimming ability of giraffes by computational analysis

Giraffes (Giraffa camelopardalis) are often stated to be unable to swim, and while few observations supporting this have ever been offered, we sought to test the hypothesis that giraffes exhibited a body shape or density unsuited for locomotion in water. We assessed the floating capability of giraffes by simulating their buoyancy with a three-dimensional mathematical/computational model. A similar model of a horse (Equus caballus) was used as a control, and its floating behaviour replicates the observed orientations of immersed horses. The floating giraffe model has its neck sub-horizontal, and the animal would struggle to keep its head clear of the water surface. Using an isometrically scaled-down giraffe model with a total mass equal to that of the horse, the giraffe's proportionally larger limbs have much higher rotational inertias than do those of horses, and their wetted surface areas are 13.5% greater relative to that of the horse, thus making rapid swimming motions more strenuous. The mean density of the giraffe model (960 gm/l) is also higher than that of the horse (930 gm/l), and closer to that causing negative buoyancy (1000 gm/l). A swimming giraffe - forced into a posture where the neck is sub-horizontal and with a thorax that is pulled downwards by the large fore limbs - would not be able to move the neck and limbs synchronously as giraffes do when moving on land, possibly further hampering the animal's ability to move its limbs effectively underwater. We found that a full-sized, adult giraffe will become buoyant in water deeper than 2.8 m. While it is not impossible for giraffes to swim, we speculate that they would perform poorly compared to other mammals and are hence likely to avoid swimming if possible.     

Giraffe translocations: A review and discussion of considerations

Giraffe populations have declined dramatically in the last three decades. Giraffe translocations are likely to increase as wildlife managers seek to augment or re-establish populations. Currently, formal practical guidance for giraffe translocations is limited. Here, we present a review of translocation guidelines emphasising planning, implementation, monitoring and evaluation, and we review giraffe behaviour and ecology to provide recommendations specific to the translocation of giraffes. We also aim to stimulate discussion about best practices for giraffe translocations and further research into the ethical and practical considerations of moving giraffes.     

Food supply and poaching limit giraffe abundance in the Serengeti

The iconic giraffe, an ecologically important browser, has shown a substantial decline in numbers across Africa since the 1990s. In Serengeti National Park, Tanzania, giraffes reached densities of 1.5–2.6 individuals km⁻² in the 1970s coincident with a pulse of Acacia tree recruitment. However, despite continued increases in woody cover between the 1980s and the 2000s, giraffe recruitment and survival rates have declined and density has dropped to only 0.3–0.4 giraffes km⁻². We used a decision table to investigate how four extrinsic factors may have contributed to these declines: food supply, predation, parasites, and poaching, which have all been previously shown to limit Serengeti ungulate populations. Lower recruitment likely resulted from a reduction in diet quality, owing to the replacement of preferred trees with unpalatable species, while decreased adult survival resulted from illegal harvesting, which appears to have had a greater impact on giraffe populations bordering the western and northern Serengeti. The Serengeti giraffe population will likely persist at low-to-moderate densities until palatable tree species regain their former abundance. Leslie matrix models suggest that park managers should meanwhile redouble their efforts to reduce poaching, thereby improving adult survival.     

Comparative use of four different marker systems for the estimation of digestibility and low food intake in a group of captive giraffes (Giraffa camelopardalis)

In a feeding trial with four captive giraffes, nutrient digestibility was determined using four different marker systems. Although cobalt‐ethylenediaminetetraacetic acid proved to have no utility as a digestibility marker in this study, reasonable values could be obtained using C₃₆ n‐alkane, acid detergent lignin, and acid insoluble ash as markers. A comparison of methods and literature data suggests that the values derived from the C₃₆ n‐alkane assay are the most reliable absolute values. Apparent digestibility ranges thus determined were 63.5–74.3% for dry matter, 73.4–82.4% for crude protein, 49.9–62.2% for neutral detergent fiber, and 49.7–63.7% for acid detergent fiber. However, digestibility data gained by the ADL method provided the most stringent inter‐individual comparisons. It is concluded that both alkanes and lignin can be used for giraffe digestibility studies. These captive giraffes ingested a smaller quantity of food than has been reported for other giraffes from both the wild and other zoos. Energetic calculations showed that these animals might be on the brink of an energy deficit. A similar situation has been described at least once before in captive giraffes, and the results are of direct relevance to the peracute mortality syndrome, a condition of captive giraffes in which severe depletion of body fat stores occurs. Reasons for the seemingly low food intake could not be elucidated, but observations suggested that these giraffes were ready to ingest more if more palatable or suitable food was offered. Monitoring food intake in other giraffe groups and designing a diet that is both palatable and nutritious are important objectives of captive giraffe management. Zoo Biol 20:315–329, 2001. © 2001 Wiley‐Liss, Inc.     

Mitochondrial DNA variability in Giraffa camelopardalis: consequences for taxonomy, phylogeography and conservation of giraffes in West and central Africa

The giraffe (Giraffa camelopardalis) still survives in four countries of West and central Africa. The populations of Niger and Cameroon are generally assigned to the subspecies peralta, but those of Chad and the Central African Republic are taxonomically problematic, as they are referred to as either peralta, or antiquorum, or congoensis. In this study, a mitochondrial fragment of 1765 nucleotide sites, covering the complete cytochrome b gene, three transfer RNAs and a large part of the control region, was sequenced to assess the relationships between several populations of giraffe. The phylogenetic analyses performed on the 12 identified haplotypes indicate that northern giraffes constitute a natural group, distinct from that of southern giraffes. Surprisingly, the giraffes of Niger are found to be more closely related to the giraffes of East Africa (subspecies rothschildi and reticulata) than to those of central Africa. We conclude therefore that the subspecies peralta contains only the Niger giraffes, whereas the subspecies antiquorum includes all populations living in Cameroon, Chad, the Central African Republic, and southwestern Sudan. We suggest that the ancestor of the Nigerian giraffe dispersed from East to North Africa during the Quaternary period and thereafter migrated to its current Sahelian distribution in West Africa, in response to the development of the Sahara desert. This hypothesis implies that Lake Mega-Chad acted as a strong geographical barrier during the Holocene, preventing any contact between the subspecies peralta and antiquorum. Our study has direct implications for conservation management, as we show that no subspecies peralta is represented in any European zoos, only in Niger, with a small population of less than 200 individuals.     

自然哺乳长颈鹿的幼仔行为研究

对成都动物园2005年和2008年出生长颈鹿幼仔在母兽哺乳情况下的1月龄内幼仔行为进行了观察和分析.发现幼长颈鹿的主要行为有卧、走、站、吃奶、跑等,其中卧和站的行为分别占全天时间的61.7%和32.3%;幼长颈鹿在10 d左右开始学习采食青草,4周龄时明显能吃到一些青草.     

The last African white giraffes live in farmers’ fields

The giraffe population (Giraffa camelopardalis) in Niger is the last representative of the peralta sub-species which lived throughout West Africa at the beginning of the twentieth century. Protected since the 1970s, giraffes cohabit with humans in cultivated landscapes. This may not have appeared to pose many problems in the past, but the relationship between farmers and giraffes has deteriorated with the expansion of cultivated land and that of the giraffe population, with reported cases of giraffes damaging crops. A survey was conducted in all the affected villages in the Kouré area to establish the nature, severity and distribution of the damage and to evaluate the local populations’ perception of the problem. Cowpeas are fed upon in the field at harvest time and in the granaries, as well as ripe mangoes, during the most critical period for giraffes’ nutrition. The vast majority of farmers interviewed consider giraffes to be rather a problem in spite of tourism revenues they can obtain from them. This opinion has individually little correlation with damage rate on crops or easy access to tourism revenues. The damage risk factors are first and foremost considered as uncontrollable by the farmers, even if technical protection measures could easily be put in place locally. The inter-relationships between the socio-economic context and the way the problem is perceived are discussed.     

Failure of a chemical spray to significantly reduce stereotypic licking in a captive giraffe

The repetitive licking of nonfood substrates is a common stereotypic behavior in captive giraffes. In this study we attempted to reduce stereotypic licking in a Masai giraffe (Giraffa camelopardalis tippelskirchi) by applying a bitter chemical (marketed as a taste deterrent to prevent the unwanted licking and chewing of substrates) to the areas of the fence licked most frequently by the giraffe. We hypothesized that this treatment would reduce stereotypic licking. However, there were no significant overall changes in stereotypic licking following treatment with the chemical spray. Although licking of the treated area was observed to decrease, the behavior increased in nontreated areas. These results suggest that the underlying motivation driving the behavior was not affected by the aversive stimulus. Because stereotypic licking in giraffes may be based on a motivation to use their tongues in foraging, more effective techniques for reducing stereotypic fence‐licking in giraffes may include increasing feeding duration by increasing the quantity, processing time, or distribution range of food. Zoo Biol 22:601–607, 2003. © 2003 Wiley‐Liss, Inc.     

Rothschild’s giraffe Giraffa camelopardalis rothschildi (Linnaeus, 1758) in East Africa: A review of population trends,taxonomy and conservation status

Giraffe populations have suffered a 40% decline in the past thirty years, making them a new priority for conservation and there are considerable uncertainty and disagreement over the taxonomic classification of giraffes. Consequently, there has never been a more critical time to fully understand the global population size and distribution of all giraffe subspecies. The Rothschild's giraffe Giraffa camelopardalis rothschildi (Linnaeus, 1758) is arguably one of the most imperilled giraffe subspecies. Once widespread across southern Sudan, Uganda and Kenya, the Rothschild's giraffe is now confined to a few, isolated and enclosed populations throughout Kenya and Uganda, with only one natural population remaining. Information about Rothschild's giraffe population size, distribution, and conservation history is patchy, and confined to recondite or inaccessible resources. Here, I present a review of taxonomy, distribution, conservation status and population size of the Rothschild's giraffe and present the most recent estimate of population sizes based on direct census data. Although the Latin name affixed to Rothschild's giraffe is subject to discussion, continued reference to this subspecies as G. c. rothschildi is strongly recommended.     

Sonomorphology of the reproductive tract in male and pregnant and non-pregnant female Rothschild's giraffes (Giraffa camelopardalis rotschildi)

The application of real-time-B-mode ultrasonography to wild and zoo animal medicine has been shown to improve the understanding of reproductive physiology in many species. Ultrasound technology is especially helpful for monitoring urogenital health, which in turn has advantages for giraffe breeding and welfare in captivity.This study aimed to ultrasonographically describe the genital organs of reproductively healthy male and female giraffes. Through the use of a restrainer, repeated rectal ultrasound examinations were performed over a 2 year period in 2.6 Rothschild's giraffes. Changes in ovarian activity were monitored throughout four different reproductive stages in the females and included immature, mature-cycling, pregnancy, post-partum-period. In the immature giraffes the ovaries showed multiple follicles of which larger ones luteinized to form pseudo-corpora lutea. By comparison, in the mature giraffes the dominant follicle reached an ovulatory diameter of 18.5 ± 0.89 mm. After ovulation, a single corpus luteum rapidly formed and reached a maximum diameter of 33.0 ± 2.4 mm on average. Pregnancy was detected for the first time by the embryonic vesicle, visualized around 28 days post copulation. Follicular development remained ongoing during early pregnancy. In the males, as in other ruminants, the bulbourethral glands and the seminal vesicles were prominent, whereas the prostate gland was indistinct.Knowledge about the reproductive tract morphology and physiology is necessary for diagnosing medical disorders and abnormalities in giraffes. The aim of this study was to help consolidate the current knowledge on basic reproductive parameters for this species.     

Androgen changes and flexible rutting behaviour in male giraffes

The social organization of giraffes (Giraffa camelopardalis) imposes a high-cost reproductive strategy on bulls, which adopt a ‘roving male’ tactic. Our observations on wild giraffes confirm that bulls indeed have unsynchronized rut-like periods, not unlike another tropical megaherbivore, the elephant, but on a much shorter timescale. We found profound changes in male sexual and social activities at the scale of about two weeks. This so far undescribed rutting behaviour is closely correlated with changes in androgen concentrations and appears to be driven by them. The short time scale of the changes in sexual and social activity may explain why dominance and reproductive status in male giraffe in the field seem to be unstable.     

Assessment of contrafreeloading preferences in giraffe (Giraffa camelopardalis)

Contrafreeloading is an intriguing phenomenon in which animals will work to obtain resources, such as food, when the same resource is simultaneously freely available. Multiple hypotheses exist for why animals might choose to contrafreeload. In this study, we assessed preferences for contrafreeloading in giraffe at the Bronx Zoo to determine whether they actually preferred to contrafreeload or were simply demonstrating a willingness to contrafreeload. Food was presented in a range of distributions between an easily accessed feeding device and a more challenging one and the giraffes’ feeding behavior at these two types of feeding devices was recorded. As the experiments progressed, more giraffe used these more challenging feeders. There was significant individual variation in the expression of preference for contrafreeloading and willingness to contrafreeload. Individual, phase of the experiment, and an interaction between these factors were significant predictors of challenge feeder use. Three foraging strategies emerged among the giraffe that we termed “freeloaders,” “contrafreeloaders,” and “opportunists.” The results of this study demonstrate that multiple indices of preference are necessary when assessing contrafreeloading behavior, and that giraffe are affected to different degrees by the factors that stimulate contrafreeloading. These results may shed light on why different individuals use complex feeding enrichment devices to varying extents.     

Hierarchical foraging by giraffe in a heterogeneous savannah,Tanzania

Understanding foraging decisions made by wildlife at different spatio‐temporal scales is important for wildlife management and conservation. We tested whether foraging decisions by Masai giraffe (Giraffa camelopardalis tippelskirchi Matschie) differed with scales; habitat, patch and tree in a heterogeneous savannah. We collected data from Arusha National Park, Tanzania, in March–May and August–October 2013. Visual observations were used to collect data on foraging behaviour. Measurements of tree height and stem height and scoring of accumulated browsing were made in 133 patches around trees where the giraffes had been seen browsing, and in a corresponding number of available patches. Giraffes selected Acacia shrub and Dodonea shrub habitats but not for water availability or predator avoidance. For patch use, giraffe selected high quantity of Acacia xanthophloea and Dodonea viscosa. Between plant species, A. xanthophloea was the most preferred and within plant species, tree quality was enhanced by tree height and high score of accumulated browsing. Generally, giraffes selected for A. xanthophloea at all scales.     

Dentition and age determination of the giraffe Giraffa camelopardalis

Thirteen tooth eruption stages and their corresponding chronological ages are descri bed from a series of giraffe jaws. These can be used for age determination in giraffes with immature dentition. Significant correlations of the lingual crown height ( r =0-957; P < 0001) and lingual occlusal surface width ( r =0-959; P < 0001) with the number of dark staining incremental lines in the cementum of thin decalcified sections of the maxillary first molar were found. The regression equations derived from these relationships provide a further method for determining the age of a giraffe. A composite plate showing maxillary first molar wear patterns provides a means of roughly assigning an age to a particular specimen. Thin sections of undecalcified teeth, mandible measurements, various other indices of tooth wear and eye lens mass were investigated and found unsuitable for age determination in this     

Behavioral development in okapis and giraffes

Observations on the behavioral development of two okapi calves and one giraffe calf were made at Brookfield Zoo. The following behaviors were monitored for 4 to 6 mo after birth; nursing duration and nursing attempts, mother-infant distance, bunting the mother's udder, lying, moving, maternal grooming, mother and infant autogrooming, object licking, tail chewing, and contact by others in the herd. Behaviors in both species showed oscillating patterns with high levels of mother-infant contact behaviors at 3–4 wk, 9–11 wk, and 14–15 wk in okapis. Giraffe infants showed similar oscillations with high periods of contact about 2–5 wk later than those in okapis. Other behaviors oscillated in concert with these, with specific correlations occurring between nursing behaviors and grooming behaviors. A main difference between okapi and giraffe development centered around maternal motivation during the high contact (regressive) periods. In okapis, after 10–12 wk there was a low rate of nursing success, whereas in giraffes the percentage of success in nursing rose with later behavioral oscillations. The regressive periods became conflict periods in okapis, whereas in the giraffe, the mother initiated the periods. This difference was in accordance with the unique strategy of infant rearing in wild giraffes in which there is an extended “hider” period when older calves are left together in shaded areas with an adult sentry. Field studies also indicated probable oscillations of mother-infant contact and a prolonged period of the mother initiating contact with her calf.     

The scent of the reticulated giraffe (Giraffa camelopardalis reticulata)

The giraffe (Giraffa camelopardalis) emits a scent that can be detected by humans over considerable distances. Dichloromethane extracts of hair samples from adult male and female reticulated giraffes (G. c. reticulata) were analysed by gas chromatography–mass spectrometry. Two highly odoriferous compounds, indole and 3-methylindole, identified in these extracts appear to be primarily responsible for the giraffe’s strong scent. Other major compounds identified were octane, benzaldehyde, heptanal, octanal, nonanal, p-cresol, tetradecanoic acid, hexadecanoic acid, and 3,5-androstadien-17-one; the last compound has not previously been identified from a natural source. These compounds may deter microorganisms or ectoparasitic arthropods. Most of these compounds are known to possess bacteriostatic or fungistatic properties against mammalian skin pathogens or other microorganisms. The levels of p-cresol in giraffe hair are sufficient to repel some ticks.     

Necks and networks: a preliminary study of population structure in the reticulated giraffe (Giraffa camelopardalis reticulata de Winston)

This paper describes a method of scoring the neck pattern of reticulated giraffes as a simple code that can be searched for in an Excel spreadsheet. This enables several hundred individual giraffe to be recognized and repeatedly found within a database. Possible sources of error are described and quantified. Data on group size, dispersal within groups and social network patterns are described. The latter is facilitated using Ucinet 6.85 for Windows, a software package that helps to visualize and analyse such networks.     

The giraffe (Giraffa camelopardalis) cervical vertebral column: a heuristic example in understanding evolutionary processes?

The current study considers the osteological morphology of the giraffe (Giraffa camelopardalis) vertebral column, with emphasis on evaluating both the adaptive and constraining features compared with other ungulates as a heuristic example in understanding evolutionary processes. Vertebral columns of giraffes varying in age from calf to adult were studied in order to understand the potential evolutionary scenarios that might have led to the modern phenotype. Data from the giraffe sample were then compared with the results from several other ungulate species, including the okapi and two species of camelids that also have visibly elongated necks. Our results show that the elongated neck of the modern giraffe appears to specifically result from evolutionary changes affecting the seven cervical vertebrae, independent of the remainder of the vertebral column. The cervical vertebrae comprise over half of the length of the total vertebral column in the giraffe. The increases in cervical vertebrae lengths also appear to be allometrically constrained, with alterations in the overall length of the neck resulting from the elongation of the entire cervical series, rather than from a single vertebra or subset of vertebrae. We place our results in the context of hypotheses concerning the origin and evolution of the giraffe neck, and the evolution of long necks in a broader sense. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 736–757.     

Urinary steroid evaluations to monitor ovarian function in exotic ungulates: II. Comparison between the giraffe (Giraffa camelopardalis) and the Okapi (Okapia johnstoni)

Ovarian activity in the female giraffe was evaluated during the nonfertile ovarian cycle and during the terminal stages of gestation. Progesterone metabolites, in the form of pregnanediol-3-glucuronide (PdG), were measured in daily random urine samples collected from four adult parous giraffes. The follicular phase averaged 4.0 ± 0.1 days in length (N = 12; range 3–5 days) and peak PdG levels in the postovulatory period averaged 30.9 ± 1.7 ng/mg Cr (N = 12). PdG levels during the latter half of gestation greatly exceeded average luteal phase levels, which is in contrast to domestic ruminants. Prior to parturition, a marked decline in PdG excretion was evident, which may be useful for anticipating this event. These data serve to elucidate ovarian function in the mature female giraffe and to provide information concerning the physiologic role of certain anomalous ovarian structures. In addition, observed similarities in the pattern of PdG excretion during the nonfertile cycles of the giraffe and the okapi indicate similar underlying physiologic processes.     

Migratory herds of wildebeests and zebras indirectly affect calf survival of giraffes

相似文献