Taurotragus Derbianus Research Articles

Status of Eastern giant eland Tragelaphus derbianus gigas (Heuglin, 1863) in the Bouba-Ndjidda National Park, North Cameroon: challenges and conservation prospects

ABSTRACT The conservation of many species may be hampered by a lack of sufficient ecological data. This study is aimed at assessing the population status of the giant eland (Tragelaphus derbianus gigas) in the BoubaNdjidda National Park (BNNP). From May to September 2021, 90 line transects spaced at 2.5 km were established, with 83 of them being census-walked once. The data collected were analysed using Distance 7.2 and QGIS software. The encounter rate of giant eland sightings was 1.91 elands/km, while the encounter rate for signs of giant eland activity was 2.11 dung/km; 0.89 footprints/km, and 0.02 carcasses/km. The abundance was estimated at 2924 individuals, with a density of 1.329 individuals/km2. The giant eland population was mainly concentrated in the central part of the park while human activities were mainly concentrated in the periphery. We also observed that poaching and transhumance/pastoralism were the most common human activities in the park. Our results revealed that human activities negatively impact the antelope’s density and distribution in the BNNP.

Individual‐based assessment of post‐translocation fitness of ungulates: Lessons from the critically endangered Derby eland conservation programme

AbstractTranslocations 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.

Spatially restricted occurrence and low abundance as key tools for conservation of critically endangered large antelope in West African savannah

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.

EVALUATION OF A VISUAL ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA) FOR PREGNANCY DETECTION IN FOUR UNGULATE SPECIES.

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.

Blood mineral profile of the critically endangered Western Derby eland (Taurotragus derbianus derbianus) in two conservation breeding reserves in Senegal.

For many nondomestic species, nutritional requirements and the challenges faced in their current habitats are unknown. This is the case of small semi-captive population of the critically endangered Western Derby eland held in two wildlife reserves (the Bandia and the Fathala) in Senegal. The aim of this study was to determine the mineral profile (Ca, P, Mg, Cu, Fe, Zn, Se, K, S) in blood serum and to identify potential mineral deficiencies. Serum data (11 individuals) were compared to other Tragelaphineae, where it was lower in almost all elements. Considerably low concentrations were recorded for Cu, Fe and Zn. Animals in the Bandia reserve had higher serum levels of Fe and K compared to the Fathala reserve and a higher serum level of S in the Fathala reserve compared to the Bandia reserve. Recorded mineral levels may reflect most likely the limited mineral background in the local environment. The knowledge of adequate nutritional requirements and health status of these animals is relevant for the conservation breeding programme. No other serum mineral reference values exist for Western Derby eland, neither for free-ranging nor captive animals. Therefore, the knowledge of reference intervals for minerals in serum may serve for monitoring of the population's health.

Comparison of divergent breeding management strategies in two species of semi-captive eland in Senegal

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.

Apex predators decline after an influx of pastoralists in former Central African Republic hunting zones

Pastoralism is spreading in Central Africa, where many protected areas are under consideration to be opened for grazing, in particular hunting zones. Here we document the loss of biodiversity followed by an influx of transhumant pastoralism into previously uninhabited and virtually pristine habitat in the Central African Republic. Our track count and camera trap surveys of 2012, 2016 and 2017 evidence a reduction of apex predators, particularly Northern lions (Panthera leo leo) and African wild dogs (Lycaon pictus), of which about 95% and 80% were lost, respectively. While some large herbivores such as Western African buffalo (Syncerus caffer nanus) or Eastern giant eland (Tragelaphus derbianus gigas) were also strongly reduced, most herbivores remain at significant densities. Apex predator populations did thus not crash due to a lack of prey, but rather due to targeted killing by herders and accompanying merchants, as interviews confirmed. Our call-up survey suggests that lions were attracted by livestock outside of actively protected areas, were they got poisoned or shot. These findings exemplify the potential negative effects of pastoralism on wildlife even in large areas with intact habitat. We thus caution against the transformation of protected areas or hunting zones into pasture land, unless such a land-use change can be carefully managed and strictly controlled.

Minerals in the Blood, Hair, and Faeces of the Critically Endangered Western Derby Eland Under Human Care in Two Wildlife Reserves in Senegal.

The widely used means of investigating animal mineral profiles are blood serum or plasma and internal organ tissues. The acquisition of these types of samples can be invasive and requires much effort. These factors become key obstacles in the case of rare and elusive species such as the Western Derby eland (Taurotragus derbianus derbianus, WDE), which is a critically endangered antelope with a current distribution limited to the Niokolo Koba National Park, and two wildlife reserves in Senegal. One of the solutions to this problem is to collect easily accessible samples, such as faeces or fur, which may provide valid information about animal mineral status. Our study focuses on determining the macroelement and microelement levels in animal blood serum, hair, and faeces, and analysing their correlations to evaluate whether hair and/or faeces can be used as a proxy for blood mineral levels. Samples were collected from 11 individual WDEs (6 males, 5 females) during translocations within two reserves. Correlations of mineral concentrations in the blood, hair, and faeces were not found except for Fe in the faeces, which was positively correlated with Fe in the hair (r = 0.64, P < 0.05) and blood (r = 0.69, P < 0.05). The lack of correlations among the different types of samples may be because of the low number of samples; hence, we recommend conducting further research with a broader dataset. Our findings, however, currently indicate that faeces and fur analyses cannot stand alone for the assessment of the mineral status and the determination of WDEs' potential mineral deficiencies.

Drivers of diet selection of critically endangered Western Derby eland during the food shortage period within conservation breeding in Senegal

Browsers represent a challenge for breeding facilities because of their sensitivity to nutritional management. Western Derby eland (Tautrotragus derbianus derbianus, WDE) is a large browsing antelope with a very diverse diet. Because of its critically endangered status, a small WDE population is kept for conservation purposes in the fenced Fathala reserve (Senegal) and during the critical, hot dry season, the animals are offered supplementary Acacia albida pods. We aimed to identify which woody plant species were preferentially selected/avoided by WDE during the period of food shortage, which plant nutritional properties were drivers of animals’ diet selection, and how this selectivity was affected by supplemental feed. The animals were selective for certain plant species, most for Piliostigma thonningi pods. Preferences decreased with a feed supplement, while avoidances remained intact. Diet selection was connected with chemical traits, mostly by negative correlations to N, Mg, Ca and hemicellulose, which disappeared or were weaker when supplemental feed was offered. Our findings indicate that large browsers during periods of food shortage must cope with inappropriate chemical composition in regard to nutrition and seek to alleviate them not only by diversification of plant species in the diet, but also by adjusting chemical diet quality as a whole.

Chinko/Mbari drainage basin represents a conservation hotspot for Eastern Derby eland in Central Africa

AbstractOne 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.

Environmental education supports conservation action by increasing the immediate and long-term environmental knowledge of children in West Africa

ABSTRACTLocal 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.

English

The Niokolo Koba National Park (NKNP) in Senegal is the last refuge of the critically endangered antelope of the subspecies Derby Eland (Taurotragus derbianus derbianus Gray, 1847). Woody plants, that provide shelters and forage for the Eland in NKNP, were assessed for their floristic diversity to characterize its confined habitat. Hence, 156 square plots of 20m x 20m were established randomly in the confined area of the Derby Eland. In each plot, list of plants species, their number of individuals, and the environmental factors (soil hardness and type, altitude, percentages of vegetation cover and fire occurrence) were noted. Fifty (50) trees species belonging to 40 genera and 29 families were recorded. The most represented families were Combretaceae (13.92%), Leguminosae-mimosoideae (12.66 %), Leguminosae-caesalpinioideae (11.39 %), Leguminosae-papilionoideae (7.59 %), Rubiaceae (7.59 %) and Tiliaceae (6.33 %). The most abundant species were Combretum glutinosum Perr. ex DC., (28.79%), Pterocarpus erinaceus Poir. (12.42%), Crossopteryx febrifuga (Afzel. ex G. Don) (7.30%), Strychnos spinosa Lam. (7.18%) and Hexalobus monopetalus (A. Rich.) Engl. & Diels (7.06 %). Altitude, fire occurrence and vegetation cover were the most important environmental factors influencing the distribution of plants species. Results suggest conservation defenders of Eland, for a sustainable management plan, to invest in in-situ fencing in order to increase possibilities of conservation of this critically endangered species in its native area. Key words: Plant inventory, specie composition, confined habitat, wild, sustainable management.

Feeding rank in the Derby eland: lessons for management

Transfers to new breeding herds and supplementary feeding are crucial management steps for small populations of ungulates. However, the successful realisation of those steps is strongly dependent on social interactions among individuals. Agonistic encounters connected with feeding determine the quality and quantity of the food accessed, and therefore directly influence food intake. We analysed the dominance relationships of mixed herds of critically endangered Western Derby eland with regard to access to supplementary food in the Bandia reserve, Senegal. We tested the influence of age and sex on feeding rank, the linearity and stability of hierarchies and the relation- ship between the position of an offspring in the hierarchy and the position of its mother. A linear hierarchy existed in all herds. Sex influenced the rank only in interaction with age. Feeding rank was significantly related to age in growing animals; in adults the effect of age was weaker. While body mass is correlated with age during the growth period and not after reaching adulthood, we concluded that the position in the hierarchy was related to the actual condition, reflecting the resource holding potential of individuals. The dominance index of a growing offspring depended on the index of its mother, but hierarchies of adult individuals were not stable. High-ranking individuals in good condition limited access to supplementary feeding to their lower-ranking herdmates. Effective supplemen- tary feeding should therefore be provided in excess amounts to enable younger and weaker individuals in need to benefit from it, despite their lower positions in the hierarchy.

Application of Spatial and Closed Capture-Recapture Models on Known Population of the Western Derby Eland (Taurotragus derbianus derbianus) in Senegal.

Camera trapping with capture-recapture analyses has provided estimates of the abundances of elusive species over the last two decades. Closed capture-recapture models (CR) based on the recognition of individuals and incorporating natural heterogeneity in capture probabilities are considered robust tools; however, closure assumption is often questionable and the use of an Mh jackknife estimator may fail in estimations of real abundance when the heterogeneity is high and data is sparse. A novel, spatially explicit capture-recapture (SECR) approach based on the location-specific capture histories of individuals overcomes the limitations of closed models. We applied both methods on a closed population of 16 critically endangered Western Derby elands in the fenced 1,060-ha Fathala reserve, Senegal. We analyzed the data from 30 cameras operating during a 66-day sampling period deployed in two densities in grid and line arrays. We captured and identified all 16 individuals in 962 trap-days. Abundances were estimated in the programs CAPTURE (models M0, Mh and Mh Chao) and R, package secr (basic Null and Finite mixture models), and compared with the true population size. We specified 66 days as a threshold in which SECR provides an accurate estimate in all trapping designs within the 7-times divergent density from 0.004 to 0.028 camera trap/ha. Both SECR models showed uniform tendency to overestimate abundance when sampling lasted shorter with no major differences between their outputs. Unlike the closed models, SECR performed well in the line patterns, which indicates promising potential for linear sampling of properly defined habitats of non-territorial and identifiable herbivores in dense wooded savanna conditions. The CR models provided reliable estimates in the grid and we confirmed the advantage of Mh Chao estimator over Mh jackknife when data appeared sparse. We also demonstrated the pooling of trapping occasions with an increase in the capture probabilities, avoiding violation of results.

Conservation genetics of the Western Derby eland (Taurotragus derbianus derbianus) in Senegal: integration of pedigree and microsatellite data

Less than 200 wild individuals of the critically endangered Western Derby eland (Taurotragus derbianus derbianus) live in the Niokolo Koba National Park (NKNP) in Senegal. A semi-captive breeding programme was established in 2000 with six founding individuals (one male, five females) transferred from the NKNP. In 2013, the population consisted of 92 individuals living in seven separate herds in the two fenced reserves of Bandia and Fathala in Senegal. Because of the low number of founding individuals in the breeding programme and the resulting high kinship, we compared the results from genealogical and genetic approaches to assess the level of genetic diversity. We used the data from the founder, F1 and F2 generations. In F1, the founder contribution was highly biased towards the only founding male, which sired all the offspring. In F2, the founder contributions were more balanced, as the male descendants of founding females entered the reproduction. This resulted in higher genetic diversity and lower inbreeding (based on pedigree data) in F2 than in F1. Results of molecular analysis using microsatellite loci confirmed the highest level of heterozygosity and lowest level of inbreeding in the founder generation; however, the implementation of a management strategy was not reflected in the empirical results. The results differed for F2, where empirical values of heterozygosity continued to decrease and inbreeding continued to increase. However, the allelic richness corresponded with the results of pedigree analyses, reflecting the more equalized founder contributions. We conclude that the overall results for genetic parameters were comparable with other breeding programmes for endangered ungulates. Nevertheless, we suggest the use of comprehensive molecular data to refine the studbook and to correct relatedness of founders and assign the missing paternities. Our suggestions correspond with the Western Derby Eland Conservation Strategy and confirm the need to introduce new founders into the semi-captive population, in order to minimize the risk of inbreeding depression and improve genetic diversity and suitability for potential reintroduction.

Healed mid-shaft fracture of an Early Roman bovine femur

We evaluated a healed fracture that was observed in the shaft of a bovine femur from an Early Roman settlement context at the site of Wange, Belgium. Using external observation and X-ray images, the specimen is described, paying particular attention to displacement of the bone ends, shortening of the bone, and callus formation. Similar fractures seen in femora of a modern Derby's antelope (Taurotragus derbianus) and of a modern eastern lowland gorilla (Gorilla gorilla graueri) are described, and we discuss why the incidence of healed femur fractures is so limited in large mammals.

Severe laminitis in multiple zoo species

A 10-year record review from a zoological institution in the western USA identified four cases of severe laminitis resulting in rotation and protrusion of the third phalanx through the sole. Laminitis is reported in a Masai giraffe (Giraffa camelopardalis tippelskirchi), a Sichuan takin (Budorcas taxicolor tibetana), a greater Malayan chevrotain (Tragulus napu) and a giant eland (Taurotragus derbianus). This is the first report of severe laminitis with pedal bone rotation and protrusion in multiple species of non-domestic hoofstock, and the first report of this disease in three of these species (takin, chevrotain, and giant eland).

Does Supplemental Feeding Affect Behaviour and Foraging of Critically Endangered Western Giant Eland in anex situConservation Site?

The western giant eland (Tragelaphus derbianus derbianus) needs appropriate management for its survival. We measured the effects of supplemental food on activity and browsing patterns during seasons of scarce natural food resources in 2008 and 2009 for a herd of six animals in the Fathala Reserve (Senegal). In response to the provision of high-quality pods of Acacia albida, animals reduced foraging time in 2008 and allocated it to resting. This pattern corresponds to the animals’ behaviour in captivity without foraging versus vigilance trade-offs and with predictable (in time and space) access to food. In 2009, supplemental feeding had no effect on behaviour and was associated with increased foraging and ruminating times than in 2008, suggesting more limited natural food resources in 2009. We recorded high species diversity in the animals’ natural diet. Supplemental food did not induce changes in browsing pattern at the plant species level, probably due to small individual effect on total nutrient and energy intake. Food supplementation, however, facilitates the animals overcoming unfavourable conditions or alleviates stress with additional rest, and could therefore assist as a conservation intervention to enhance fitness.

Does supplemental feeding affect behaviour and foraging of critically endangered western giant eland in an ex situ conservation site?

The western giant eland (Tragelaphus derbianus derbianus) needs appropriate management for its survival. We measured the effects of supplemental food on activity and browsing patterns during seasons of scarce natural food resources in 2008 and 2009 for a herd of six animals in the Fathala Reserve (Senegal). In response to the provision of high-quality pods of Acacia albida, animals reduced foraging time in 2008 and allocated it to resting. This pattern corresponds to the animals’ behaviour in captivity without foraging versus vigilance trade-offs and with predictable (in time and space) access to food. In 2009, supplemental feeding had no effect on behaviour and was associated with increased foraging and ruminating times than in 2008, suggesting more limited natural food resources in 2009. We recorded high species diversity in the animals’ natural diet. Supplemental food did not induce changes in browsing pattern at the plant species level, probably due to small individual effect on total nutrient and energy intake. Food supplementation, however, facilitates the animals overcoming unfavourable conditions or alleviates stress with additional rest, and could therefore assist as a conservation intervention to enhance fitness.

Description of a new species of Eimeria Schneider, 1875 (Apicomplexa: Eimeriidae) from the western Derby eland Taurotragus derbianus derbianus Gray (Artiodactyla: Bovidae) in Senegal

Examination of faecal samples from semi-captive western Derby elands Taurotragus derbianus derbianus Gray, in the Bandia and Fathala Reserves of Senegal, revealed the presence of oöcysts of the genus Eimeria Schneider, 1875 that we considered to represent a new species, Eimeria derbiani n. sp. The new species possesses nearly ellipsoidal oöcysts (length/width ratio 1.3) with a bi-layered wall and an average size of 27.6 × 21.5 μm. E. derbiani possesses a micropyle covered by a micropylar cap and ovoidal, single-layered sporocysts with an average size of 14.9 × 7.7 μm, each with a Stieda body. Sporozoites of E. derbiani possess a large refractile body and a nucleus. Sporulation lasted for 2 days at 23°C. The new species is differentiated from the two species parasitising Taurotragus oryx Pallas, E. canna Triffitt, 1924 and E. triffittae Yakimoff, 1934.