Black-backed jackals (Canis mesomelas) from semi-arid rangelands in South Africa harbour Hepatozoon canis and a Theileria species but apparently not Babesia rossi

Despite the importance of disease as a wildlife management challenge in South Africa, baseline data on the epidemiology of pathogens occurring in free-ranging species has received little attention to date. Black-backed jackals (Canis mesomelas) are a wide-ranging, abundant carnivore with substantial economic importance due to their role in livestock depredation. They are known reservoirs hosts of Babesia rossi, a virulent pathogen in domestic dogs in sub-Saharan Africa. We investigated the prevalence and diversity of tick-borne pathogens (TPBs) including Babesia, Theileria, Hepatozoon, Ehrlichia and Anaplasma species, together with host-attached tick diversity, in a black-backed jackal population from the semi-arid Central Karoo, a small-livestock farming region in South Africa. Using reverse line blot hybridisation, we screened 43 blood samples and sequenced the 18S rRNA gene from positive samples to confirm and characterise pathogen identity using a phylogenetic framework. Hepatozoon canis, a ubiquitous pathogen of domestic and wild canids globally, was observed in 47% of jackals, while a Theileria sp. most similar to T. ovis, a piroplasm found in small livestock, was observed in 5% of jackals. No Babesia, Ehrlichia or Anaplasma species were identified, although a Sarcocystis sp. sequence was isolated from one jackal. Host-attached ticks (n = 20) comprised three species, Amblyomma marmoreum, Haemaphysalis elliptica/zumpti and Ixodes rubicundus, commonly known ticks in the region. In summary, prevalence of TBPs in black-backed jackals from this semi-arid rangeland region was lower than in jackal populations in more mesic regions. These jackals were apparently not infected with B. rossi. While this study is one of the first investigations into the epidemiology of TBPs infecting jackals and adds to the sparse literature, further studies which span landscape uses, climate conditions and seasonality are encouraged.Institute for Communities and Wildlife in Africa, University of Cape Town; Foundational Biodiversity Information Programme, National Research Foundation of South Africa; University of Cape Town Science Faculty Grant and National Research Foundation of South Africa; National Research Foundation Freestanding Masters bursary and Wilderness Wildlife Trust bursary.https://www.elsevier.com/locate/vprsr2022-03-31hj2022Centre for Veterinary Wildlife StudiesVeterinary Tropical Disease

Animal welfare considerations for using large carnivores and guardian dogs as vertebrate biocontrol tools against other animals

Introducing consumptive and non-consumptive effects into food webs can have profound effects on individuals, populations and communities. This knowledge has led to the deliberate use of predation and/or fear of predation as an emerging technique for controlling wildlife. Many now advocate for the intentional use of large carnivores and livestock guardian dogs as more desirable alternatives to traditional wildlife control approaches like fencing, shooting, trapping, or poisoning. However, there has been very little consideration of the animal welfare implications of deliberately using predation as a wildlife management tool. We assess the animal welfare impacts of using dingoes, leopards and guardian dogs as biocontrol tools against wildlife in Australia and South Africa following the ‘Five Domains’ model commonly used to assess other wildlife management tools. Application of this model indicates that large carnivores and guardian dogs cause considerable lethal and non-lethal animal welfare impacts to the individual animals they are intended to control. These impacts are likely similar across different predator-prey systems, but are dependent on specific predator-prey combinations; combinations that result in short chases and quick kills will be rated as less harmful than those that result in long chases and protracted kills. Moreover, these impacts are typically rated greater than those caused by traditional wildlife control techniques. The intentional lethal and non-lethal harms caused by large carnivores and guardian dogs should not be ignored or dismissively assumed to be negligible. A greater understanding of the impacts they impose would benefit from empirical studies of the animal welfare outcomes arising from their use in different contexts

Movements and growth rates of the broadnose sevengill shark Notorynchus cepedianus in southern Africa: results from a long-term cooperative tagging programme

Top predators are important components of healthy ecosystems but are at risk of overexploitation due to insufficient data on life-history characteristics and population dynamics to guide management. We investigated the movements and growth rates of the broadnose sevengill shark Notorynchus cepedianus in southern Africa, using data from the Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORI-CFTP). A total of 3 513 N. cepedianus were tagged between 1984 and 2017, with 195 (5.6%) recaptured. Distribution ranged from Cape Fria, northern Namibia, to the Great Kei River, Eastern Cape, South Africa, representing a range extension of ~200 km in comparison with that previously reported. Most captures occurred along the west coast of South Africa, and recaptures showed connectivity between the west and south coasts, but not between South Africa and Namibia. Site fidelity was evident, with the majority of recaptures (66.6%, n = 130) occurring 500 km from the release site. Growth rates for N. cepedianus at reference precaudal lengths of 100 cm and 160 cm were estimated to be 4.7 cm y–1 and 4.0 cm y–1, respectively, which are lower than previous growth estimates. The slow growth rate and site fidelity evident in N. cepedianus, coupled with being captured in several commercial fisheries, necessitate the need for improved management of this species

Infanticide and expulsion of females in a cooperative mammal

In cooperative groups of suricates (Suricata suricatta), helpers of both sexes assist breeding adults in defending and feeding pups, and survival rises in larger groups. Despite this, dominant breeding females expel subordinate females from the group in the latter half of their (own) pregnancy, apparently because adult females sometimes kill their pups. Some of the females that have been expelled are allowed to rejoin the group soon after the dominant female's pups are born and subsequently assist in rearing the pups. Female helpers initially resist expulsion and repeatedly attempt to return to their natal group, indicating that it is unlikely that dominant females need to grant them reproductive concessions to retain them in the group

Bringing objectivity to wildlife management: Welfare effects of guardian dogs

Letter to the Edito

A Case of Natural Queen Succession in a Captive Colony of Naked Mole-Rats, Heterocephalus glaber

Naked mole-rats occur in large colonies where usually a single queen monopolizes reproduction. Queen succession occurs from within usually as a result of aggressive encounters with subordinate females that queue for reproductive succession following colony instability, which inevitably results in death of either the queen or the challenging conspecific. We monitored a queen succession following the death of the breeding male in a colony of the naked mole-rat, Heterocephalus glaber, prior to, during as well as after replacement of the original breeding female. The response of the pituitary luteotrophs was investigated in the non-reproductive females during this period of instability by the administration of endogenous gonadotrophin releasing hormone (GnRH) and evaluating the subsequent luteinising hormone (LH) response in the blood. Larger and older non-breeding females engaged in aggressive encounters that culminated in death. The new breeding successor which arose from within the colony was a large female who continued to procreate. The six non-breeding females that were killed during reproductive takeover were larger and older females which exhibited elevated basal circulating LH concentrations as well as increased pituitary sensitivity as measured by the amount of releasable LH to an exogenous GnRH challenge. By contrast, non-breeding females that survived the succession were smaller and younger animals with reduced basal and GnRH challenged LH concentrations. Likewise, five non-breeding males which were heavier and older than those non-breeding males which survived were killed. These animals did not, however, show elevated basal or exogenous GnRH challenged LH concentrations when compared to the surviving males. The non-breeding animals of both sexes which survived the reproductive takeover event represented individuals which posed a minimal threat to the new successor and hence promoted the continuation of the marked reproductive skew that is prevalent in this highly inbred colonial subterranean hystricomorph.The authors thank R.P. Millar, Department of Chemical Pathology, University of Cape Town, for donating the mammalian GnRH. We also thank the National Institute of Biological Standards and Control, Hertfordshire, England, for the LH pituitary preparation (2nd International Standard 1988, code 80/552). The work was supported by research grants from the then Foundation for Research Development (to N.C.B. and J.U.M.J.), the University of Pretoria (to N.C.B.) and the University of Cape Town (to J.U.M.J). This study was approved by the Animal Ethics Committee of the University of Cape Townhttp://africanzoology.journals.ac.za/am2013ab201

Individual contributions to babysitting in a cooperative mongoose, Suricata suricatta.

Evolutionary explanations of cooperative breeding based on kin selection have predicted that the individual contributions made by different helpers to rearing young should be correlated with their degree of kinship to the litter or brood they are raising. In the cooperative mongoose or meerkat, Suricata suricatta, helpers babysit pups at the natal burrow for the first month of pup life and frequent babysitters suffer substantial weight losses over the period of babysitting. Large differences in contributions exist between helpers, which are correlated with their age, sex and weight but not with their kinship to the young they are raising. Provision of food to some group members raises the contributions of individuals to babysitting. We discuss the implications of these results for evolutionary explanations of cooperative behaviour

Bone remodeling in the longest living rodent, the naked mole‐rat: Interelement variation and the effects of reproduction

The pattern of bone remodeling of one of the most peculiar mammals in the world, the naked mole-rat (NMR), was assessed. NMRs are known for their long lifespans among rodents and for having low metabolic rates. We assessed long-term in vivo bone labeling of subordinate individuals, as well as the patterns of bone resorption and bone remodeling in a large sample including reproductive and non-reproductive individuals (n = 70). Over 268 undecalcified thin cross-sections from the midshaft of humerus, ulna, femur and tibia were analyzed with confocal fluorescence and polarized light microscopy. Fluorochrome analysis revealed low osteogenesis, scarce bone resorption and infrequent formation of secondary osteons (Haversian systems) (i.e., slow bone turnover), thus most likely reflecting the low metabolic rates of this species. Secondary osteons occurred regardless of reproductive status. However, considerable differences in the degree of bone remodeling were found between breeders and non-breeders. Pre-reproductive stages (subordinates) exhibited quite stable skeletal homeostasis and bone structure, although the attainment of sexual maturity and beginning of reproductive cycles in female breeders triggered a series of anabolic and catabolic processes that up-regulate bone turnover, most likely associated with the increased metabolic rates of reproduction. Furthermore, bone remodeling was more frequently found in stylopodial elements compared to zeugopodial elements. Despite the limited bone remodeling observed in NMRs, the variation in the pattern of skeletal homeostasis (interelement variation) reported here represents an important aspect to understand the skeletal dynamics of a small mammal with low metabolic rates. Given the relevance of the remodeling process among mammals, this study also permitted the comparison of such process with the well-documented histomorphology of extinct therapsids (i.e., mammalian precursors), thus evidencing that bone remodeling and its endocortical compartmentalization represent ancestral features among the lineage that gave rise to mammals. It is concluded that other factors associated with development (and not uniquely related to biomechanical loading) can also have an important role in the development of bone remodeling.CONICYT; National Research Foundation and DST-NRF.http://www.wileyonlinelibrary.com/journal/joahj2022Mammal Research InstituteZoology and Entomolog