Status and social structure of the critically endangered dama gazelle (Nanger dama) in the Aïr & Ténéré National Nature Reserve, Niger

Abstract Minimizing the effects of inbreeding is one of the main challenges facing conservation managers of small populations. When inbreeding negatively affects the offspring survival, the short- and long-term viability of the species can be severely compromised. In the present study, we evaluated the genetic parameters affecting calf survival during the perinatal period (PS) and between the perinatal period and weaning (WS) in the captive population of the critically endangered mhorr gazelle ( Nanger dama mhorr ). The dataset analysed included 2185 calf records from a total pedigree of 2739 animals born between 1971 and 2021. The models with the best predictive value showed heritabilities of the direct genetic effect of 0.259 (SD = 0.052) for the PS and 0.123 (SD = 0.047) for the WS. Only the WS was affected by maternal permanent environmental effect ( c 2 = 0.035, SD = 0.026). No genetic correlation was observed between the direct genetic effects of both traits. The maximum inbreeding coefficient of the calf was shown to reduce the PS almost 30% points and the inbreeding coefficient of the dam, around 15% points of the WS. Despite this, the genetic and phenotypic trends over the years of both traits were positive, which demonstrates the effectiveness of the mating strategy applied and the effect of no artificial selection that has occurred in this captive population.

Abstract Habitat use influences the survival and fitness of animals. Habitat quality and food availability in spring and summer are crucial determinants of ungulate population dynamics, peaking in spring and drastically decreasing in summer in Mediterranean region. Here, over a 2-year period we examine foraging habitat use in both spring and summer of 3 threatened gazelle species living in sympatry in a private reserve in Morocco: Cuvier’s Gazelle (Gazella cuvieri), Dama Gazelle (Nanger dama), and Dorcas Gazelle (G. dorcas). We observed differences among species—Cuvier’s Gazelle foraged in woodland, Dama Gazelle in grassland, and Dorcas Gazelle in scrubland—with differences being mediated by seasonal effects as all species broadened their foraging habitat use in summer. We observed differences between years in foraging patterns of Dama Gazelle and Dorcas Gazelle, reflecting greater herb and scrub cover in 2018, potentially related to greater rainfall. Given the seasonal and annual differences observed, reductions in rainfall predicted with the progression of changing climatic conditions in the Mediterranean basin would reduce the availability of food resources and heighten the vulnerability of these species. The study illustrates interspecific coexistence through food resource partitioning of the 3 species, contributing to support conservation management actions of their populations in setting up structured reintroduction programs within their range.

Social interactions, including agonistic behavior, are very important for the management and welfare of individuals forming groups in captivity. One of the main concerns for the stability and durability of adult male groups is a noticeable level of intraspecific aggression. This study comprises a Social Network Analysis to illustrate social structure in different groups of captive Saharan Dorcas gazelles (Gazella dorcas neglecta). Our main objectives were to examine the relationship between agonistic, affiliative, and association networks and their reciprocity, assessing also whether the agonistic networks can conform to a linear dominance hierarchy. For these purposes, we recorded the behavior of 23 adult males organized in five herds, three composed only of Saharan Dorcas gazelle males and two mixed herds in which there were also Mhorr gazelle males (Nanger dama mohor). Observations were carried out during 295 h through scan sampling. We found no correlation between the affiliative and association networks in any group, although there was a significant correlation between the agonistic and association networks in mixed-species groups which was not present in single-species groups. Overall, there was no consistent reciprocity in either affiliative nor agonistic networks and none of the agonistic networks showed a linear structure. These results indicate that affiliative behavior in Saharan Dorcas gazelles offers distinctive and valuable information about the bonds between individuals, however, their dominance structure is far more complex than previously thought. As information provided by affiliative and proximity behaviors is different in this species, we suggest considering affiliative interactions to stablish affinity between individuals. Evaluating different social behaviors and not only agonistic interactions in later studies, is also recommended to develop a more accurately daily management in zoos that guarantee group stability and individuals' welfare, which will improve the conservation of captive populations.

Breeding programs have an essential role in the recovery of threatened populations through optimal genetic management and mating strategies. The dama gazelle (Nanger dama) is a North African ungulate listed as critically endangered. The mhorr subspecies is extinct in the wild and currently survives thanks to the creation in 1971 of an ex situ breeding program. The aim of the present study was to assess the evolution of genetic variability in this mhorr gazelle captive population, as well as the mating strategy used in two reference populations studied (Almeria and Europe). The entire pedigree, with 2739 animals, was analyzed to measure demographic characters, pedigree completeness level, probability of gene origin, level of relatedness and genetic structure of the population. The population size has been progressively increasing, with up to 264 individuals alive in Europe at the time of the study. The average number of equivalent complete generations was 5.55. The effective number of founders and ancestors was both 3, and the founder genome equivalent was 1.99. The genetic contributions of the four main ancestors were unbalanced. The average values of inbreeding and average relatedness for the whole pedigree were, respectively, 28.34% and 50.14%. The effective population size was 8.7 by individual increase in inbreeding and 9.8 by individual increase in coancestry. F‐statistics evidenced a very small level of population subdivision (FST = 0.033370). The mating strategy used, based on the minimum coancestry of the individuals, has minimized the losses of genetic variability and helped to balance the genetic contributions between ancestors. The strategy also avoided large subdivisions within the population and the appearance of new bottlenecks. This study shows how pedigree analysis can both be used to determine the genetic variability of the population and to assess the influence of the mating strategy used in the breeding program on such variability.

Various environmental, individual, and species-specific factors may affect digestive efficiency in wild ruminants. The study of faecal nutritional components is a commonly used technique to understand these effects, assuming that faecal nitrogen and fibre contents reflect the diet's nutritional quality and digestibility. Recent studies have highlighted the relatively high influence of factors like sex, age, weight or body condition on digestive efficiency. This manuscript is focused on the inter-specific variability in faecal nutritional components under the same feeding regime, using three captive populations of closely related gazelles as model species. Faecal samples from 193 individuals were analysed through Near InfraRed Spectroscopy. Species, sex and age influence on faecal nitrogen and fibres (ADF and NDF) were investigated. We found inter-specific differences in the faecal content of the three studied nutritional components. Cuvier's gazelle showed lower faecal nitrogen content, suggesting lower digestive efficiency than dorcas and dama gazelles. Sex and age also had a moderate effect, especially in faecal nitrogen, but these effects were not constant across the three studied species. On the contrary, faecal fibres were highly constant (i.e., dependent on diet quality). These results confirm that individual factors affecting faecal nutritional components are also species-specific.

Wild animals play a critical role in maintenance and transmission of various tick-borne pathogens. It is essential to identify these wild host species that can serve as important reservoirs of tickborne diseases. In the present study we investigated Dama gazelle (Nanger dama) as a potential novel reservoir of Theileria spp. A total of 53 blood samples collected from Dama gazelle as part of the Al Ain Zoo preventive medicine program were screened for Theileria spp. by qPCR using a commercial assay, followed by additional studies using conventional PCR targeting an approximate 450-base pair (bp) fragment of the V4 hypervariable region of the 18S ribosomal RNA (rRNA) gene. Sequencing and phylogenetic analysis of a subset (20) of PCR amplicons revealed Theileria isolates from gazelles of Al Ain Zoo clustered closely to Theileria sp. Dama Gazelle (AY735115) from USA and were far away or did not cluster with the known Theileria spp. of ruminants namely T. annulata, T. ovis, T. orientalis, T. luwenshuni, T.parva and T.sinensis. Theileria genotypes detected in gazelles of present study were clearly distinct from the other common theileria species of ruminants. The present finding throws light on the critical role of reservoir host in maintenance and transmission of pathogen.

Dama gazelle is a threatened and rarely studied species found primarily in northern Africa. Human pressure has depleted the dama gazelle population from tens of thousands to a few hundred individuals. Since 1970, a founder population consisting of the last 17 surviving individuals in Western Sahara has been maintained in captivity, reproducing naturally. In preparation for the future implementation of assisted reproductive technology, certain aspects of dama gazelle reproductive biology have been established. However, the role played by semiochemical-mediated communications in the sexual behavior of dama gazelle remains unknown due partially to a lack of a neuroanatomical or morphofunctional characterization of the dama gazelle vomeronasal organ (VNO), which is the sensory organ responsible for pheromone processing. The present study characterized the dama gazelle VNO, which appears fully equipped to perform neurosensory functions, contributing to current understanding of interspecies VNO variability among ruminants. By employing histological, lectin-histochemical, and immunohistochemical techniques, we conducted a detailed morphofunctional evaluation of the dama gazelle VNO along its entire longitudinal axis. Our findings of significant structural and neurochemical transformation along the entire VNO suggest that future studies of the VNO should take a similar approach. The present study contributes to current understanding of dama gazelle VNO, providing a basis for future studies of semiochemical-mediated communications and reproductive management in this species. RESEARCH HIGHLIGHTS: This exhaustive immunohistological study of the vomeronasal organ (VNO) of the dama gazelle provides the first evidence of notable differences in the expression of neuronal markers along the rostrocaudal axis of the VNO. This provides a morphological basis for the implementation of pheromones in captive populations of dama gazelle.

(1) Background: Peste des petits ruminants (PPR) is a highly contagious animal disease affecting small ruminants, leading to significant economic losses. There has been little published data on PPR virus (PPRV) infection in the United Arab Emirates (UAE); (2) Methods: four outbreaks reported in goats and Dama gazelle in 2021 were investigated using pathological and molecular testing; (3) Results: The infected animals showed symptoms of dyspnea, oculo-nasal secretions, cough, and diarrhea. Necropsy findings were almost similar in all examined animals and compliant to the classical forms of the disease. Phylogenetic analysis based on N gene and F gene partial sequences revealed a circulation of PPRV Asian lineage IV in the UAE, and these sequences clustered close to the sequences of PPRV from United Arab Emirates, Pakistan, Tajikistan and Iran; (4) Conclusions: PPRV Asian lineage IV is currently circulating in the UAE. To the best of our knowledge, this is a first study describing PPRV in domestic small ruminant in the UAE.

Abstract The Ouadi Rimé–Ouadi Achim Reserve (Réserve de l'Ouadi Rimé–Ouadi Achim) in central Chad supports large numbers of livestock and rare antelopes, and is the site of ongoing reintroductions of the scimitar-horned oryxOryx dammahand addaxAddax nasomaculatus. We present results of surveys conducted during 2011–2019 to examine patterns of relative abundance and distribution of dorcas gazellesGazella dorcas, dama gazellesNanger damaand livestock in relation to each other and to water sources in a 3,500 km2area in the centre of the Reserve. Dorcas gazelles numbered 7,700–18,000, moving extensively across the area. Livestock varied between c. 2,000 and 68,000 tropical livestock units across surveys, with density doubling in the wet season. Dorcas gazelle distribution was negatively associated with livestock, and livestock density was positively associated with artificial water sources. Dorcas gazelle densities were positively associated with locations where there had been wild fires in the 6 months prior to a survey. Dama gazelles were encountered only 13 times, insufficient to estimate their population size reliably. Opportunistic observations suggest dama gazelles avoid livestock and burnt ground. Our findings highlight the importance of the Reserve. We recommend the designation of a large, well-managed conservation priority zone in the Reserve's core area in which no further development of water resources is permitted. Management of livestock numbers within this zone at or below current levels is essential to integrate national goals for both biodiversity conservation and pastoralism development.

Applying genomics to metapopulation management in North American insurance populations of southern sable antelope (Hippotragus niger niger) and addra gazelle (Nanger dama ruficollis)

Inbreeding threatens the survival of small populations by producing inbreeding depression, but also exposes recessive deleterious effects in homozygosis allowing for genetic purging. Using inbreeding-purging theory, we analyze early survival in four pedigreed captive breeding programs of endangered ungulates where population growth was prioritized so that most adult females were allowed to contribute offspring according to their fitness. We find evidence that purging can substantially reduce inbreeding depression in Gazella cuvieri (with effective population size Ne = 14) and Nanger dama (Ne = 11). No purging is detected in Ammotragus lervia (Ne = 4), in agreement with the notion that drift overcomes purging under fast inbreeding, nor in G. dorcas (Ne = 39) where, due to the larger population size, purging is slower and detection is expected to require more generations. Thus, although smaller populations are always expected to show smaller fitness (as well as less adaptive potential) than larger ones due to higher homozygosis and deleterious fixation, our results show that a substantial fraction of their inbreeding load and inbreeding depression can be purged when breeding contributions are governed by natural selection. Since management strategies intended to maximize the ratio from the effective to the actual population size tend to reduce purging, the search for a compromise between these strategies and purging could be beneficial in the long term. This could be achieved either by allowing some level of random mating and some role of natural selection in determining breeding contributions, or by undertaking reintroductions into the wild at the earliest opportunity.

Dama gazelles (Nanger dama Pallas, 1766) are critically endangered within their native habitat of northern Africa’s Sahelo-Saharan Zone. However, several Texas ranches maintain populations that provide a hedge against extinction and that can provide suitable stock for conservation projects, including reintroduction. For these initiatives, there is a critical need for information on spatial requirements of male dama gazelles. This is especially the case, because population increase is hindered by aggressive behaviour of males kept within limited areas. Adult males kill other males. We report on the spatial distribution and interaction potential (interanimal distances) of male eastern dama gazelles (N. dama ruficollis) from a population living on 8 996 ha of fenced rangeland in West Texas, USA. We fitted five males with GPS-radio collars and tracked their positions every 3 h for one year. Adult males (n = 3) maintained annual 95% Kernel Home Ranges (KHR) averaging 1 783 ha with 50% core areas averaging 440 ha. Average distance between adults with adjacent home ranges was 2.8 to 4.6 km, with only four contacts within 20 m recorded. Subadult males (n = 2) had more diffuse home ranges and a common core area. They only associated in a loose bachelor group for part of the time. Their space use can overlap with that of adult males. When spatial requirements are met, problems caused by aggression can be minimised. Small sample size prevents definite recommendations, but results point to productive avenues for additional study to enhance management of other ex situ populations.

Simple SummaryGood-quality sperm samples are needed for the development and implementation of sperm cryopreservation, in vitro fertilization and artificial insemination. These reproductive biotechnologies play an important role in the conservation and management of domestic and wild species. The aim of this study was to explore the effect of seasonality and social environment on sperm quality in three endangered gazelles: Cuvier’s, dorcas and Mohor gazelles. Periods of better sperm quality were related with higher conception rates in Cuvier’s and Mohor gazelles but not in dorcas. Cuvier’s gazelle showed higher sperm quantity in April and Mohor gazelle in April and August and correlated with environmental data. In dorcas gazelle, a drop in sperm quality was observed in October. Housing conditions did not affect sperm quality in Cuvier’s and Mohor gazelles, whereas dorcas males housed with females showed lower semen quality than males kept alone or with males. Considering these results could improve the success of reproductive biotechnologies in these three species.Knowledge of factors affecting semen quality could be of great importance for the collection and preservation of semen from threatened animals. To assess the effect of seasonality, sperm parameters and testosterone levels were examined throughout the year and compared with the distribution of conceptions. Cuvier’s gazelle showed higher sperm quantity in April, coinciding with one peak of conceptions. In dorcas gazelle, sperm parameters showed a drop in October. However, percentage of conceptions increased during that month. In Mohor gazelle, sperm quality was best in April and August, in agreement with higher conception rates and high testosterone levels. Percentage of conceptions was correlated with photoperiod and rainfall in Cuvier’s gazelle and with temperature in Mohor gazelle. To assess the effect of social environment, semen quality, testosterone and cortisol levels were quantified in males housed alone, in bachelor groups or with females. No differences were seen in Cuvier’s and Mohor gazelles’ semen traits, whereas dorcas males housed with females showed lower semen quality than males kept alone or with other males. Overall, ejaculate quality is influenced by seasonal factors in the three gazelle species, while social factors only appear to affect that of dorcas gazelle.

This study evaluated the use of a commercially available, visual enzyme-linked immunosorbent assay (ELISA) for diagnosis of pregnancy in okapi (Okapia johnstoni), gerenuk (Litocranius walleri), eastern giant eland (Tragelaphus derbianus spp. gigas), and dama gazelle (Nanger dama). This assay has been validated for use in domestic cattle, sheep, goats, and water buffalo. Unlike other blood-based pregnancy associated glycoprotein (PAG) detection methods, this assay does not require sophisticated laboratory equipment for detection or interpretation and can therefore be utilized in many settings. Banked serum samples from gerenuk (n = 11), giant eland (n = 4), dama gazelle (n = 33) and okapi (n = 3) were tested, and a pregnant and nonpregnant sample from each individual were included. The ELISA showed 100% sensitivity and specificity in gerenuk and giant eland samples, and 0% sensitivity in dama gazelle and okapi samples. Using this assay, pregnancy was detected by 7-8 wk gestation in gerenuk and 6 wk in giant eland. These results are consistent with previous studies that were able to accurately detect pregnancy in other members of the family Bovidae, but it is possible that PAGs present in okapi and dama gazelle are structurally dissimilar relative to the intended test target, and are therefore unrecognizable using this test. The faint positivity in the dama gazelle assays may be due to cross-reactivity with other proteins in the sample, or due to inconsistent binding with the dama gazelle PAG. This ELISA appears to be an accurate, rapid, and inexpensive method of point-of-care pregnancy diagnosis in gerenuk and giant eland, but not okapi and dama gazelle. Additional studies should be pursued to further characterize the limits of pregnancy detection using this assay in gerenuk and giant eland, and to investigate the validity of this test in other nondomestic ruminant species.

Habitat requirements of the Mhorr gazelle: What does this species need to survive in the wild?

West Nile virus (WNV) and Usutu virus (USUV) are zoonotic arboviruses. These flaviviruses are mainly maintained in the environment through an enzootic cycle involving mosquitoes and birds. Horses and humans are incidental, dead-end hosts, but can develop severe neurological disorders. Nevertheless, there is little data regarding the involvement of other mammals in the epidemiology of these arboviruses. In this study, we performed a serosurvey to assess exposure to these viruses in captive birds and mammals in a zoo situated in the south of France, an area described for the circulation of these two viruses. A total of 411 samples comprising of 70 species were collected over 16 years from 2003 to 2019. The samples were first tested by a competitive enzyme-linked immunosorbent assay. The positive sera were then tested using virus-specific microneutralization tests against USUV and WNV. USUV seroprevalence in birds was 10 times higher than that of WNV (14.59% versus 1.46%, respectively). Among birds, greater rhea (Rhea Americana) and common peafowl (Pavo cristatus) exhibited the highest USUV seroprevalence. Infections occurred mainly between 2016–2018 corresponding to a period of high circulation of these viruses in Europe. In mammalian species, antibodies against WNV were detected in one dama gazelle (Nanger dama) whereas serological evidence of USUV infection was observed in several Canidae, especially in African wild dogs (Lycaon pictus). Our study helps to better understand the exposure of captive species to WNV and USUV and to identify potential host species to include in surveillance programs in zoos.

Abstract Habitat selection information is important for both breeding on Texas ranches and repatriation in Africa. This is especially true for the critically endangered dama gazelle (Nanger dama). Exotic dama gazelles of the eastern subspecies (N. dama ruficollis) wearing GPS-radio collars were tracked for one year on two Texas ranches. Three adult and two subadult males were collared from a large (8,996 ha) pasture in west Texas. Next, collars went on all males plus all females released into a 202 ha Edwards Plateau pasture (seven adult females, one maturing male, and one to three adult males). On both sites, the gazelles favored the less steep terrain of the Ector soil series. Adult male core areas averaged 440 ha in west Texas (vegetation sparse) and 57 ha on the Edwards Plateau (dense food stands). These relationships allowed for estimation of the number of adult males that could be stocked in the larger pasture while still allowing room for the males to spread out. No special affinity for water sources was found, although dama gazelles do drink during hot weather when water is available. There was no consistent seasonal distributional change noted. On both Texas sites, the gazelles survive on natural browse. Where there are feeders, competition from larger animals kept gazelles out. For breeding or restoring populations, flat-to-gently rolling terrain with ample browse is best. Shade and water are important, and any supplemental feed requires access. There also needs to be enough favored habitat to accommodate the adult males without dangerous conflict.

Since 2006 the Dama gazelle has been considered a critically endangered species by the IUCN. At present, the captive population is distributed in several zoos around the world. Bioparc (Valencia,...

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