Jörg Melzheimer

An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats

Background The diet of free-ranging carnivores is an important part of their ecology. It is often determined from prey remains in scats. In many cases, scat analyses are the most efficient method but they require correction for potential biases. When the diet is expressed as proportions of consumed mass of each prey species, the consumed prey mass to excrete one scat needs to be determined and corrected for prey body mass because the proportion of digestible to indigestible matter increases with prey body mass. Prey body mass can be corrected for by conducting feeding experiments using prey of various body masses and fitting a regression between consumed prey mass to excrete one scat and prey body mass (correction factor 1). When the diet is expressed as proportions of consumed individuals of each prey species and includes prey animals not completely consumed, the actual mass of each prey consumed by the carnivore needs to be controlled for (correction factor 2). No previous study controlled for this second bias. Methodology/Principal Findings Here we use an extended series of feeding experiments on a large carnivore, the cheetah (Acinonyx jubatus), to establish both correction factors. In contrast to previous studies which fitted a linear regression for correction factor 1, we fitted a biologically more meaningful exponential regression model where the consumed prey mass to excrete one scat reaches an asymptote at large prey sizes. Using our protocol, we also derive correction factor 1 and 2 for other carnivore species and apply them to published studies. We show that the new method increases the number and proportion of consumed individuals in the diet for large prey animals compared to the conventional method. Conclusion/Significance Our results have important implications for the interpretation of scat-based studies in feeding ecology and the resolution of human-wildlife conflicts for the conservation of large carnivores.

Modeling the viability of the free‐ranging cheetah population in Namibia: an object‐oriented Bayesian network approach

Conservation of free-ranging cheetah (Acinonyx jubatus) populations is multi faceted and needs to be addressed from an ecological, biological and management perspective. There is a wealth of published research, each focusing on a particular aspect of cheetah conservation. Identifying the most important factors, making sense of various (and sometimes contrasting) findings, and taking decisions when little or no empirical data is available, are everyday challenges facing conservationists. Bayesian networks (BN) provide a statistical modeling framework that enables analysis and integration of information addressing different aspects of conservation. There has been an increased interest in the use of BNs to model conservation issues, however the development of more sophisticated BNs, utilizing object-oriented (OO) features, is still at the frontier of ecological research. We describe an integrated, parallel modeling process followed during a BN modeling workshop held in Namibia to combine expert knowledge and data about free-ranging cheetahs. The aim of the workshop was to obtain a more comprehensive view of the current viability of the free-ranging cheetah population in Namibia, and to predict the effect different scenarios may have on the future viability of this free-ranging cheetah population. Furthermore, a complementary aim was to identify influential parameters of the model to more effectively target those parameters having the greatest impact on population viability. The BN was developed by aggregating diverse perspectives from local and independent scientists, agents from the national ministry, conservation agency members and local fieldworkers. This integrated BN approach facilitates OO modeling in a multi-expert context which lends itself to a series of integrated, yet independent, subnetworks describing different scientific and management components. We created three subnetworks in parallel: a biological, ecological and human factors network, which were then combined to create a complete representation of free-ranging cheetah population viability. Such OOBNs have widespread relevance to the effective and targeted conservation management of vulnerable and endangered species.

First evidence of hemoplasma infection in free-ranging Namibian cheetahs (Acinonyx jubatus)

Infections with feline hemotropic mycoplasmas (hemoplasmas) have been documented in domestic cats and free-ranging feline species with high prevalences in Iberian lynxes (Lynx pardinus), Eurasian lynxes (Lynx lynx), European wildcats (Felis silvestris silvestris), African lions (Panthera leo) in Tanzania and domestic cats in South Africa. The prevalence of hemoplasmas has not yet been investigated in free-ranging felids in southern Africa. In this study we screened 73 blood samples from 61 cheetahs in central Namibia for the presence of hemoplasmas using quantitative real-time PCR. One of the cheetahs tested PCR-positive. Phylogenetic analysis based on partial sequencing of the 16S rRNA and RNAse P genes revealed that the isolate belongs to the Mycoplasma haemofelis/haemocanis group. This is the first molecular evidence of a hemoplasma infection in a free-ranging cheetah.

The Conflict between Cheetahs and Humans on Namibian Farmland Elucidated by Stable Isotope Diet Analysis

Large areas of Namibia are covered by farmland, which is also used by game and predator species. Because it can cause conflicts with farmers when predators, such as cheetahs (Acinonyx jubatus), hunt livestock, we assessed whether livestock constitutes a significant part of the cheetah diet by analysing the stable isotope composition of blood and tissue samples of cheetahs and their potential prey species. According to isotopic similarities, we defined three isotopic categories of potential prey: members of a C4 food web with high δ15N values (gemsbok, cattle, springhare and guinea fowl) and those with low δ15N values (hartebeest, warthog), and members of a C3 food web, namely browsers (eland, kudu, springbok, steenbok and scrub hare). We quantified the trophic discrimination of heavy isotopes in cheetah muscle in 9 captive individuals and measured an enrichment for 15N (3.2‰) but not for 13C in relation to food. We captured 53 free-ranging cheetahs of which 23 were members of groups. Cheetahs of the same group were isotopically distinct from members of other groups, indicating that group members shared their prey. Solitary males (n = 21) and males in a bachelor groups (n = 11) fed mostly on hartebeest and warthogs, followed by browsers in case of solitary males, and by grazers with high δ15N values in case of bachelor groups. Female cheetahs (n = 9) predominantly fed on browsers and used also hartebeest and warthogs. Mixing models suggested that the isotopic prey category that included cattle was only important, if at all, for males living in bachelor groups. Stable isotope analysis of fur, muscle, red blood cells and blood plasma in 9 free-ranging cheetahs identified most individuals as isotopic specialists, focussing on isotopically distinct prey categories as their food.

Gammaretrovirus-specific antibodies in free-ranging and captive Namibian cheetahs.

ABSTRACT The cheetah population in Namibia is the largest free-ranging population in the world and a key population for research regarding the health status of this species. We used serological methods and quantitative real-time PCR to test free-ranging and captive Namibian cheetahs for the presence of feline leukemia virus (FeLV), a gammaretrovirus that can be highly aggressive in populations with low genetic diversity, such as cheetahs. We also assessed the presence of antibodies to other gammaretroviruses and the responses to a FeLV vaccine developed for domestic cats. Up to 19% of the free-ranging cheetahs, 27% of the captive nonvaccinated cheetahs, and 86% of the captive vaccinated cheetahs tested positive for FeLV antibodies. FeLV-antibody-positive free-ranging cheetahs also tested positive for Rauscher murine leukemia virus antibodies. Nevertheless, FeLV was not detectable by quantitative real-time PCR and no reverse transcriptase activity was detectable by product-enhanced reverse transcriptase assay in the plasma of cheetahs or the supernatants from cultures of peripheral blood mononuclear cells. The presence of antibodies to gammaretroviruses in clinically healthy specimens may be caused either by infection with a low-pathogenic retrovirus or by the expression of endogenous retroviral sequences. The strong humoral immune responses to FeLV vaccination demonstrate that cheetahs can respond to the vaccine and that vaccination against FeLV infection may be beneficial should FeLV infection ever become a threat, as was seen in Iberian lynx and Florida panthers.

A breath test to assign carnivore diets to browsers or grazers

Cheetahs Acinonyx jubatus are important predators of herbivores in African ecosystems, and several methods to determine their diet have been used in the past. We applied a novel method to quickly assess the diet of cheetahs with respect to grazing and browsing herbivores, i.e. we analysed the stable carbon isotope ratio (δ13CV-PDB) of cheetah breath to separate individuals feeding predominantly on browsers or grazers, respectively. Browsers and grazers are contrasting in their muscle δ13CV-PDB, because of their isotopically distinct C3 or C4 plant diet, respectively. Muscle δ13CV-PDB of six abundant local potential prey species of cheetahs confirmed that kudu Tragelaphus strepsiceros and springbok Antidorcas marsupialis browsed on C3 plants, whereas gemsbok Oryx gazella, hartebeest Alcelaphus buselaphus, warthog Phacochoerus africanus and cattle Bos taurus predominantly grazed on C4 plants. Breath δ13CV-PDB of the cheetahs followed the bimodal frequency distribution of the prey species with six cheetahs being assigned to the C4 food web and three to the C3 food web. Breath tests may be a suitable method to delineate the trophic membership of carnivores to C3 and C4 food webs when animals are chemically immobilised for other purposes.

Cheetahs have a stronger constitutive innate immunity than leopards

As a textbook case for the importance of genetics in conservation, absence of genetic variability at the major histocompatibility complex (MHC) is thought to endanger species viability, since it is considered crucial for pathogen resistance. An alternative view of the immune system inspired by life history theory posits that a strong response should evolve in other components of the immune system if there is little variation in the MHC. In contrast to the leopard (Panthera pardus), the cheetah (Acinonyx jubatus) has a relatively low genetic variability at the MHC, yet free-ranging cheetahs are healthy. By comparing the functional competence of the humoral immune system of both species in sympatric populations in Namibia, we demonstrate that cheetahs have a higher constitutive innate but lower induced innate and adaptive immunity than leopards. We conclude (1) immunocompetence of cheetahs is higher than previously thought; (2) studying both innate and adaptive components of immune systems will enrich conservation science.

The distribution and numbers of cheetah (Acinonyx jubatus) in southern Africa

Assessing the numbers and distribution of threatened species is a central challenge in conservation, often made difficult because the species of concern are rare and elusive. For some predators, this may be compounded by their being sparsely distributed over large areas. Such is the case with the cheetah Acinonyx jubatus. The IUCN Red List process solicits comments, is democratic, transparent, widely-used, and has recently assessed the species. Here, we present additional methods to that process and provide quantitative approaches that may afford greater detail and a benchmark against which to compare future assessments. The cheetah poses challenges, but also affords unique opportunities. It is photogenic, allowing the compilation of thousands of crowd-sourced data. It is also persecuted for killing livestock, enabling estimation of local population densities from the numbers persecuted. Documented instances of persecution in areas with known human and livestock density mean that these data can provide an estimate of where the species may or may not occur in areas without observational data. Compilations of extensive telemetry data coupled with nearly 20,000 additional observations from 39 sources show that free-ranging cheetahs were present across approximately 789,700 km2 of Namibia, Botswana, South Africa, and Zimbabwe (56%, 22%, 12% and 10% respectively) from 2010 to 2016, with an estimated adult population of 3,577 animals. We identified a further 742,800 km2 of potential cheetah habitat within the study region with low human and livestock densities, where another ∼3,250 cheetahs may occur. Unlike many previous estimates, we make the data available and provide explicit information on exactly where cheetahs occur, or are unlikely to occur. We stress the value of gathering data from public sources though these data were mostly from well-visited protected areas. There is a contiguous, transboundary population of cheetah in southern Africa, known to be the largest in the world. We suggest that this population is more threatened than believed due to the concentration of about 55% of free-ranging individuals in two ecoregions. This area overlaps with commercial farmland with high persecution risk; adult cheetahs were removed at the rate of 0.3 individuals per 100 km2 per year. Our population estimate for confirmed cheetah presence areas is 11% lower than the IUCN’s current assessment for the same region, lending additional support to the recent call for the up-listing of this species from vulnerable to endangered status.

Gut microbiomes of free-ranging and captive Namibian cheetahs: Diversity, putative functions and occurrence of potential pathogens

Although the significance of the gut microbiome for host health is well acknowledged, the impact of host traits and environmental factors on the interindividual variation of gut microbiomes of wildlife species is not well understood. Such information is essential; however, as changes in the composition of these microbial communities beyond the natural range might cause dysbiosis leading to increased susceptibility to infections. We examined the potential influence of sex, age, genetic relatedness, spatial tactics and the environment on the natural range of the gut microbiome diversity in free‐ranging Namibian cheetahs (Acinonyx jubatus). We further explored the impact of an altered diet and frequent contact with roaming dogs and cats on the occurrence of potential bacterial pathogens by comparing free‐ranging and captive individuals living under the same climatic conditions. Abundance patterns of particular bacterial genera differed between the sexes, and bacterial diversity and richness were higher in older (>3.5 years) than in younger individuals. In contrast, male spatial tactics, which probably influence host exposure to environmental bacteria, had no discernible effect on the gut microbiome. The profound resemblance of the gut microbiome of kin in contrast to nonkin suggests a predominant role of genetics in shaping bacterial community characteristics and functional similarities. We also detected various Operational Taxonomic Units (OTUs) assigned to potential pathogenic bacteria known to cause diseases in humans and wildlife species, such as Helicobacter spp., and Clostridium perfringens. Captive individuals did not differ in their microbial alpha diversity but exhibited higher abundances of OTUs related to potential pathogenic bacteria and shifts in disease‐associated functional pathways. Our study emphasizes the need to integrate ecological, genetic and pathogenic aspects to improve our comprehension of the main drivers of natural variation and shifts in gut microbial communities possibly affecting host health. This knowledge is essential for in situ and ex situ conservation management.

Feliform carnivores have a distinguished constitutive innate immune response

ABSTRACT Determining the immunological phenotype of endangered and threatened populations is important to identify those vulnerable to novel pathogens. Among mammals, members of the order Carnivora are particularly threatened by diseases. We therefore examined the constitutive innate immune system, the first line of protection against invading microbes, of six free-ranging carnivore species; the black-backed jackal (Canis mesomelas), the brown hyena (Hyena brunnea), the caracal (Caracal caracal), the cheetah (Acinonyx jubatus), the leopard (Panthera pardus) and the lion (Panthera leo) using a bacterial killing assay. The differences in immune responses amongst the six species were independent of their foraging behaviour, body mass or social organisation but reflected their phylogenetic relatedness. The bacterial killing capacity of black-backed jackals, a member of the suborder Caniformia, followed the pattern established for a wide variety of vertebrates. In contrast, the five representatives of the suborder Feliformia demonstrated a killing capacity at least an order of magnitude higher than any species reported previously, with a particularly high capacity in caracals and cheetahs. Our results suggest that the immunocompetence of threatened felids such as the cheetah has been underestimated and its assessment ought to consider both innate and adaptive components of the immune system. Summary: The innate immunocompetence of six free-ranging carnivores is independent of their foraging behaviour, body mass or social organisation but reflects their phylogenetic relatedness.