The dama gazelle (Nanger dama (Pallas, 1766)) is one of the largest of all gazelles, and also one of the world's most endangered antelopes listed as Critically Endangered on the IUCN Red List. Today, only a few small and highly scattered populations persist, mainly in Niger and Chad. This study provides recent insights into the population status, structure, and phenotypic diversity of dama gazelles in the Air & Tenere National Nature Reserve (ATNNR), focusing on the Mount Takolokouzet, and based on 15 field missions conducted between 2017 and 2023. Distribution and relative abundance were assessed using direct observations, indirect signs, and camera traps. The Kilometric Index of Abundance (KIA) averaged 0.058 for direct observations and 0.16 for indirect observations, showing a positive trend over time, particularly for indirect evidence. Camera trap data revealed an overall capture rate (CTR) of 1.59 independent events per 100 trap-days, with increased detection during recent targeted efforts. Demographic analysis was based on 39 direct sightings (84 individuals) and 200 independent camera trap events (244 individuals). Solitary individuals were primarily adults, representing 83 % of camera trap records and less than half of direct sightings. Group sizes were from 2 to 7 (direct) and 2-4 (camera traps), with an overall mean of 2.95 individuals. Adults were dominant in both datasets, while juveniles and subadults comprised less than 20 % of individuals. Calving was observed in two distinct seasonal periods. Phenotypic diversity in the dama gazelle population at ATNNR was marked by traits associated with different coat patterns. The N. d. dama phenotype was the most common (73 %), with smaller proportions exhibiting distinct variations (18 % and 9 %). This suggests a phenotypically mixed population, but caution is needed as subspecies differentiation remains debated. The variation may represent a spectrum rather than distinct subspecies. Our results highlight the importance and fragility of a small, little-known population of dama gazelle on Mount Takolokouzet. The consistently low proportion of young individuals highlights concerns about recruitment. Our findings justify urgent conservation measures focused on securing refuges, reducing disturbance, sustaining monitoring, and protecting breeding females during calving peaks, while ecological drivers will be examined in future work.
The rapid loss of biodiversity and the associated reduction and fragmentation of habitats means that ex situ populations have become an important part of species conservation. These populations, which are often established from a small number of founders, require careful management to avoid the negative effects of genetic drift and inbreeding. Although the inclusion of molecular data is recommended, their availability for captive breeding management remains limited. The aim of this study was to evaluate the relationship between the levels of genetic diversity in six spiral-horned antelope taxa bred under human care and their respective management strategies, conservation status, demography, and geographic origin, using 10 nuclear DNA microsatellite loci and mitochondrial control region DNA sequences. Our findings include associations between genetic diversity and management intensity but also with the diversity and contribution of wild populations to captive founders, with some populations apparently composed of animals from divergent wild lineages elevating captive genetic diversity. When population sizes are large, the potential advantages of maximizing genetic diversity in widely outcrossed populations may need careful consideration with respect to the potential disruption of adaptive diversity. Genetic data serve as a robust tool for managing captive populations, yet their interpretation necessitates a comprehensive understanding of species biology and history.
Resting is an integral component of animal behavior, contributing to one’s fitness through careful optimization strategies. In large herbivores, resting periods are driven by availability of food, presence of predators, and thermoregulation. A combination of these drivers leads to high variability in resting behaviors and their time allocation throughout the day. However, these drivers are rarely evaluated in the wild. Megaherbivores, including giraffe (Giraffa spp.), adopt social resting strategies, which enable them to optimize the cost–benefit ratio, with rest and vigilance varying with group size and composition. We investigated resting behavior of the West African giraffe (G. camelopardalis peralta) living in a human-populated landscape dominated by agropastoralism activities in Niger. Through direct observation, we evaluated the influence of group size and composition, and presence of livestock and humans on giraffe resting behavior. We concluded that giraffe increased their resting time with shorter distance to other giraffe and livestock. Livestock did not negatively impact giraffe behavior; rather, they provided a kind of “safe environment”. Human presence resulted in only minor changes in vigilance of giraffe and did not significantly affect their resting time. Our findings highlight a positive instance of human–giraffe coexistence in a human-dominated landscape, attributed to the long-term benefits of conservation efforts.
The West African giraffe (Giraffa camelopardalis peralta) was historically spread across much of the Sudano-Sahelian zone but is now restricted to Niger. Several factors resulted in their dramatic decline during the late 20th century. In 1996, only 49 individuals remained, concentrated in the ‘Giraffe Zone’. Conservation activities implemented by the Government of Niger, supported by local communities and NGOs, facilitated their population numbers to increase. This review summarizes past and present conservation activities and evaluates their impact to advise and prioritize future conservation actions for the West African giraffe. The long-term conservation of the West African giraffe is highly dependent on the local communities who live alongside them, as well as supplementary support from local and international partners. Recent conservation initiatives range from community-based monitoring to the fitting of GPS satellite tags to better understand their habitat use, spatial movements to expansion areas, and environmental education to the establishment of the first satellite population of West African giraffe in Gadabedji Biosphere Reserve, the latter serving as a flagship for the future restoration of large mammal populations in West Africa. The integration of modern technologies and methods will hopefully provide better-quality data, improved spatial analyses, and greater understanding of giraffe ecology to inform the long-term management of West African giraffe.
Summary The West African giraffe is restricted to Niger, but historically it inhabited much of the Sudano-Sahelian zone. The population is concentrated in the ‘Giraffe Zone’ (GZ), an unprotected area with a high human population density. Since the mid-1990s, the giraffe population has steadily increased mainly due to the collective social and conservation initiatives of the government, non-governmental organizations and the local community. In 2018, the first West African giraffe satellite population was established through the reintroduction of eight individuals into Gadabedji Biosphere Reserve (GBR). In this study, we aimed to describe the current state of human–giraffe coexistence, human attitudes towards giraffe and human habits of natural resources use through a questionnaire survey conducted in the GZ and GBR. Although most of the GZ respondents highlighted crop damage caused by giraffe, we also found overall positive attitudes towards the animals. Most respondents from both sites expressed positive attitudes towards giraffe, highlighting that they do not see poaching as a major current threat. However, the giraffe population continues to be directly threatened by habitat loss through firewood cutting, livestock overgrazing and agriculture expansion. Long-term conservation of the West African giraffe is dependent on better habitat protection and understanding of current human–giraffe coexistence through ensuring that giraffe presence will benefit local communities across their range.
Animal movement behaviours are shaped by diverse factors, including resource availability and human impacts on the landscape. We generated home range estimates and daily movement rate estimates for 149 giraffe (Giraffa spp.) from all four species across Africa to evaluate the effects of environmental productivity and anthropogenic disturbance on space use. Using the continuous time movement modelling framework and a novel application of mixed effects meta-regression, we summarized overall giraffe space use and tested for the effects of resource availability and human impact on 95% autocorrelated kernel density estimate (AKDE) size and daily movement. The mean 95% AKDE was 359.9 km(2) and the mean daily movement was 14.2 km, both with marginally significant differences across species. We found significant negative effects of resource availability, and significant positive effects of resource heterogeneity and protected area overlap on 95% AKDE size. There were significant negative effects of overall anthropogenic disturbance and positive effects of the heterogeneity of anthropogenic disturbance on daily movements and 95% AKDE size. Our results provide unique insights into the interactive effects of resource availability and anthropogenic development on the movements of a large-bodied browser and highlight the potential impacts of rapidly changing landscapes on animal space-use patterns.
Studying suckling behaviour has been used to understand parent-offspring conflict in mammals when the mother adjusts the amount of resources invested into an offspring during the lactation period. However, most studies report this information as a by-product of studying other types of suckling behaviour, like allosuckling. We aimed to understand this decision-making process by analysing the filial suckling bouts where the interval from the previous filial suckling bout was known. We used a captive population of threatened dorcas gazelles (Gazella dorcas) as a model species. Our findings showed that the lactation period in dorcas gazelle is characterised by three distinctive behavioural stages, where the behaviour of mother and calf changes rather fast, despite the progressive change in suckling duration. Early lactation (EL), when suckling bouts are always terminated by the calf; mid lactation (ML), when both the mother and the calf indistinctly may end up the suckling bouts; and late lactation (LL), when it is the mother who unfailingly ends lactation events. Also, we found evidence of male-biased maternal investment, as mothers tended to offer more investment towards male calves when suckling Additionally, we confirmed a compensational mechanism whereby calves born later in the birth season were suckled for longer (in terms of duration of suckling bouts) than calves born earlier, resulting in similar weaning dates for all studied calves. Therefore, many aspects may be overlooked if the influence of allosuckling on standard suckling is not considered when analysing suckling behaviour. Thus, we suggest this method of standard suckling behaviour analysis, where all behaviours which may alter the calves' demands and mothers' resources are removed (i.e., suckling attempts, allosuckling, and suckling after allosuckling).
Abstract Translocations have become an essential tool in animal conservation for establishing and maintaining viable populations. Yet, the viability of a population is implicitly based on the individual fitness, that is on the survival and reproduction of individuals. Individual‐based assessments of post‐translocation fitness are challenging in the wild while conservation breeding programs may provide vital insights. Long‐term breeding records of semi‐captive (fenced) small population of the Western Derby eland (Taurotragus derbianus derbianus) running in two fenced reserves in Senegal present a case study. This study shows that transport distance and the individual's age at translocation influence animal post‐translocation survival rates and individual reproductive performance. The most critical period for the antelope's post‐translocation survival was the first 2 years following the event, with higher mortalities reported after long‐distance transport in an ecologically novel environment. The first successful calving of translocated females was postponed by 1 year, but the life‐long reproductive performance was not affected. However, higher calf survival in a habitat similar to that in the wild suggests a non‐negligible effect of the habitat on individual fitness, thus crucial to conservation decisions on translocating threatened species.
Suckling of a non-filial calf, or allosuckling, is an extreme case of allomaternal care in mammals. There have been many hypotheses postulated in an attempt to explain this behaviour; however, the supporting evidence differs, together with the conclusions drawn from the investigated variables. Previously, suckling bout rejection was analysed, and the milk theft and reciprocity hypotheses were both determined as the most appropriate explanation of allosuckling in giraffe. In this study, seven hypotheses were tested using different behavioural parameters, namely suckling bout frequency, suckling bout duration, and time spent suckling. It is well-documented that these parameters are associated with various aspects in ungulate biology; for example, suckling rejection typically reflects milk intake and parent–offspring conflict, whereas the suckling bout duration and frequency is associated with social behaviours (affiliation, bonding, social stress). In total, 22 nursing females and 47 suckling calves were observed, in four Czech zoos during a five-year period. The correlation of the observed parameters between the reciprocal female-calf dyads was found to be in line with the reciprocity hypothesis. In addition, non-filial calves tried to steal the milk from non-maternal females, supporting the milk theft hypothesis. Thus, the results support both the reciprocity and milk-theft hypotheses as the most plausible explanation of allosuckling in giraffe, and illustrates the importance of using suckling bout duration and frequency, and the time spent suckling, as behavioural parameters that may aid in explaining the extremity of maternal investment, such as allosuckling.
The effective conservation of mammals on the brink of extinction requires an integrated socio-ecological approach, yet the updated ecological knowledge of species remains fundamental. This study brings spatiotemporal behaviour, population structure, age-specific survival rates, and population size estimate of the Western Derby eland (WDE) in the Niokolo Koba National Park (NKNP), Senegal, investigated during dry seasons 2017 and 2018. WDE was strongly localised in the core area of NKNP (< 5%), active throughout the day with the highest peak in the hottest daytime, with a mean group size 7.6 ± SE 8.9. The adult sex ratio was female-biased and showed low annual adult male survival rates. The population consisted of high proportion of juveniles, whilst adults did not exceed 40%. The estimated population density was 0.138 WDE/km2 (± 0.0102) and estimated size 195 WDE in NKNP (CI95 from 54 to 708 individuals). Findings highlighted that the WDE population has potential to expand in the NKNP, due to an underutilized capacity. The age-specific vital rates indicate adult males as the most vulnerable; suggesting either an increase in the large predators' population, livestock encroachment pressure, and/or poaching. Findings imply that targeted monitoring with science-based interpretation may bring forward strong conservation solutions to the protected area management decision-makers.
Breeding management of small populations may have a critical influence on the development of population characteristics in terms of levels of genetic diversity and inbreeding. Two populations of antelope sister species - Critically Endangered Western Derby eland (Tauroragus derbianus derbianus) and non-native Least Concern Cape eland (Taurotragus oryx oryx) bred under different management strategies were studied in Senegal, Western Africa. The aims of the study were to compare the population genetic parameters of the two species and to test for the presence of interspecific hybrids. In total, blood and tissue samples from 76 Western Derby elands and 26 Cape elands were investigated, using 12 microsatellite markers. No hybrid individuals were detected in the sampled animals within the multispecies enclosure in Bandia Reserve, Senegal. The parameters of genetic polymorphism indicated much lower genetic diversity in Western Derby elands compared to Cape elands. On the other hand, the coefficient of inbreeding was low in both species. It is hypothesized that this could be a positive effect of strict population management of Western Derby elands, which, despite the loss of genetic diversity, minimizes inbreeding.
Maternal investment and maternal care provided by mammalian females can change during their ontogeny. Differences may be related to the age and/or experience (parity) of the female. Several hypotheses have been postulated to explain changes in the rate of maternal care of females during their lifetime. The residual reproductive value hypothesis supposes a higher rate of maternal care in older and more experienced females, in contrast the targeted reproductive effort hypothesis predicts lower levels of maternal care in older and/or more experienced females. To test these hypotheses we investigated nursing bout frequency and time devoted to nursing as predictors of the rate of maternal care, and rate of successful nursing bouts as a predictor of maternal investment, in captive giraffe (22 females, 47 calves in four zoos). We also considered the high rate of allonursing (nursing of non-filial calves) which appeared in all herds. The nursing and allonursing bout frequency as well as the total time devoted to nursing and allonursing increased with increasing parity and age of the female, thus supporting the residual reproductive value hypothesis. In addition, maternal experience of individual females in terms of parity rather than age was responsible for variation in maternal behaviour. This suggests that variation depends on individual experiences.
In polygynous mammals, females are expected to bias maternal investment in favor of male calves. The mother should invest more in males to enhance their reproductive success in adulthood, or the males require greater investment as they are bigger and stronger than females. In this study, we used nursing duration to compare the difference in the amount of maternal investment provided by females. We compared differences according to sex of the offspring and the influence of calves' identification by sniffing, using captive giraffes (Giraffa camelopardalis) as a model. Since a high intensity of allonursing (nursing of a nonfilial calf) was reported in giraffes, we also focused on the difference between filial and nonfilial calves. We observed 22 nursing females and 47 suckling calves in four zoological gardens in the Czech Republic from 2007 to 2011. Nursing duration was longer for male calves than for female calves and for calves sniffed by the nursing female regardless whether the calves were filial or nonfilial. We conclude that male calves are more demanding for the amount of investment received and they are more successful in this effort than female calves. Since females provided investment in the same way to filial and nonfilial calves, selection for higher demand for investment by male than by female offspring should be important for their future development. Our results also demonstrate the importance of sniffing for the identification of the suckling calf by the female.
Abstract Population numbers of Kordofan giraffe (Giraffa camelopardalis antiquorum) have declined throughout its range by more than 85% in the last three decades, including in the isolated easternmost population found in the Garamba National Park (NP) in the Democratic Republic of Congo. We provide new data on the conservation status and ecology of Kordofan giraffe in Garamba NP, specifically on the current population dynamics, distribution patterns, and spatial ecology for informed conservation management decisions. Data were gathered between September 26, 2016, and August 17, 2017, through direct observation and from eight GPS satellite collars deployed in early 2016. Movements, distribution patterns, and autocorrelated kernel density home ranges were estimated using the Continuous‐Time Movement Modeling (CTMM) framework. We then compared results with home ranges calculated using the kernel density estimation (95% KDE) method. The Garamba NP population was estimated to be 45 giraffe with a female‐dominated sex ratio (35% males; 65% females), and adult‐dominated age class ratio (11.2% juveniles; 17.7% subadults; 71.1% adults). The giraffe's distribution was limited to the south‐central sector of the Park, and giraffe were divided over different areas with some degree of connectivity. The average giraffe home range size was 934.3 km2 using AKDE and 268.8 km2 using KDE. Both methods have shown surprisingly large home ranges despite of the relatively high humidity of Garamba NP. Based on the outcomes of this research, urgent conservation action is needed to protect Garamba's remaining giraffe population.
One of the largest of antelopes, Derby eland (Taurotragus derbianus), is an important ecosystem component of African savannah. While the western subspecies is Critically Endangered, the eastern subspecies is classified as least concern. Our study presents the first investigation of population dynamics of the Derby eland in the Chinko/Mbari Drainage Basin, Central African Republic, and assesses the conservation role of this population. We analysed data from 63 camera traps installed in 2012. The number of individuals captured within a single camera event ranged from one to 41. Herds were mostly mixed by age and sex, mean group size was 5.61, larger during the dry season. Adult (AD) males constituted only 20% of solitary individuals. The overall sex ratio (M:F) was 1:1.33, while the AD sex ratio shifted to 1:1.52, reflecting selective hunting pressure. Mean density ranged from 0.04 to 0.16 individuals/km2, giving an estimated population size of 445–1,760 individuals. Chinko harbours one of the largest documented populations of Derby eland in Central Africa, making Chinko one of its potential conservation hotspots.
Nursing behaviour is one component of mammalian life history strategy that demonstrates context-dependent flexibility within species. Wild giraffes live in groups and feed themselves over large area. In the zoo, giraffes are kept in enclosures with abundant food resources. We aimed to analyse whether the nursing behaviour of giraffes differs between the zoo and nature reserve and discuss which factor (food intake, presence of predators, population density) can explain the difference. We observed seven and four female–calf pairs in the Bandia reserve, Senegal, and in Prague Zoo, Czech Republic, respectively. Nursing bouts were less frequent and longer and calves were less successful in nursing solicitations in the reserve, as females there seemed to be more selective for nursing times and locations, likely due to presence of predators and differences in food intake. Allonursing occurred more frequently in the zoo which can be attributed to higher population density in captive conditions.
Local communities play a key role in the sustainability of any conservation program. We evaluated the impact of an environmental education program for school children in the surroundings of the Delta du Saloum Biosphere reserve (Senegal) dedicated to the conservation of African charismatic fauna with the critically endangered Western Derby eland as a conservation flagship. Questionnaires evaluating knowledge and attitudes were filled in by children before and after the program in 2008 and 2009. We found a significant increase in knowledge that carries the potential to support conservation activities of protected area management. This knowledge alone is, however, not enough to change behavior and attitudes, proving the need to approach the problem in context of a complex, targeted awareness campaign.
Allonursing, the nursing of nonfilial offspring, has been reported in a number of mammalian species; however, very few studies have investigated more than three hypotheses. The aim of our study was to investigate seven hypotheses explaining allonursing in captive giraffes. During 2007-2011, we observed 24 females and 37 calves in four zoological gardens in the Czech Republic, recording 2514 suckling events. We found that 83% of the females allonursed a nonfilial calf and 86.5% of calves allosuckled from a nonmaternal female; thus giraffes represent one of the highest occurrences of allonursing among nondomesticated mammals. The nonfilial calves more often allosuckled together with the filial ones than alone and tried to adopt positions where they may be harder to recognize, providing evidence for the milk theft hypothesis. In addition, the probability that a calf successfully allosuckled at least once from any female was higher when its mother allonursed successfully at least once than when she rejected calves. However, we found no evidence for the same rate of allonursing between reciprocal dyads of females and calves. Thus, we suggest that allonursing in giraffes is caused by offspring trying to steal milk and that females may tolerate this behaviour if reciprocal, in line with recent findings about giraffe sociality. (C) 2016 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd.
Despite being regularly bred in zoos, giraffes remain a challenge, especially in terms of feeding. Assessment of factors influencing growth and weight changes during ontogeny, as well as analysis of weight fluctuations in adult individuals, may become a critical point in captive diet evaluation. Knowledge about weight is a crucial husbandry tool; however, such data are rarely acquired. Using a unique dataset from regularly weighed Rothschild giraffes (Giraffa camelopardalis rothschildi) from Prague zoo, we determined the growth functions of male and female giraffes and calculated weight gains during giraffe ontogeny. The mean weights of adult males and females were 1307 ± 52 and 835 ± 45 kg, respectively confirming the large overall dimensions of G. c. rothschildi in comparison with other giraffe subspecies. As the giraffe is a polygynous species showing considerable sexual dimorphism, we expected male calves to have larger first weights and faster growth during the most intensive period of maternal care. Growth rates and daily weight gains were higher in males than in females during the whole postnatal period. Males grew faster and longer than females. However, differences in weight between males and females appeared as late as after 1 year of age. The weight of adult males and non-pregnant adult females fluctuated significantly across seasons, being the highest during the autumn and winter months, respectively which may reflect the different effects of sexual activity and feeding ratios in males and females. Zoo Biol. 35:423-431, 2016. © Wiley Periodicals, Inc.