Wildlife health in human-modified landscapes: epidemiology of tick-borne pathogens affecting black-backed jackals and caracals

Despite the importance of disease as a wildlife management challenge, baseline research on the epidemiology of pathogens occurring in wildlife populations within both rural and urban landscapes has received little attention to date. The aim of this study was to improve our understanding of wildlife health in human-modified landscapes in South Africa, by providing comparisons of body condition, host-attached tick diversity and tick-borne pathogen (TBP) epidemiology of two common mesocarnivore species, the black-backed jackal (Canis mesomelas) and caracal (Caracal caracal). Jackals (n=46) and caracals (n=27) were sampled from small livestock farmlands in the Central Karoo region, in addition to caracals from farmlands in Namaqualand (n=14), and the urban matrix of the Cape Peninsula (n=16). Body condition was evaluated using both ratio (Body Mass Index) and residual (Ordinary Least Squares) methods, and morphometry was compared with historical datasets for each species. There was no apparent effect of sex, age class or location on body condition of jackals or caracals. Host-attached tick diversity was highest in urban caracals compared with the two other caracal populations, possibly indicating that they are exposed to a greater diversity of potential tick vectors. Molecular methods (mPCR/RLB; conventional PCR screening and phylogenetic analysis) used to screen for selected pathogens of veterinary and/or zoonotic concern, including Ehrlichia, Anaplasma, Babesia and Theileria species, revealed that Central Karoo jackals exhibited a lower prevalence of TBPs, compared with sympatric caracals. Hepatozoon canis, a ubiquitous pathogen of domestic and wild canids globally, was observed in 46.5% of jackals. Theileria ovis, a piroplasm of small livestock, was found in 4.7% of jackals. Jackals and caracals appear to be distinct in their TBP epidemiological roles, despite sharing similar tick communities. Pathogens found in caracals include Hepatozoon felis, Babesia felis, Babesia leo and a potentially undescribed Babesia species, genetically similar to B. venatorum, an emerging zoonosis. An Anaplasma species previously described in South African domestic dogs was also found in the urban caracals. All caracals were infected with at least one TBP. Together, these findings suggest that land use does not significantly influence the body condition of these adaptable predators, but that there is a health cost associated with living in the urban space. Cape Peninsula caracals show substantially higher rates of TBP co-infection (81% versus 14.8% and 0% in farmlands) and greater pathogen diversity compared to farmland caracals. The findings of this study include numerous examples of previously undescribed genetic diversity of tick-borne pathogens infecting South African mesocarnivores living in transformed landscapes. This work adds to our understanding of wildlife health within the 'One Health' framework and represents the first detailed examination of TBPs in jackals on farmlands and is also the first work that focuses specifically on TPBs in caracals anywhere in the world

Habitat use and diet preference of extralimital giraffes in the Kgalagadi Transfrontier Park

Extralimital giraffe introductions in the south-western region of Kgalagadi Transfrontier Park, South Africa, may result in changes to the vegetation structure for the region through overutilization of two keystone tree species in the area. In the areas where giraffe density was highest, I determine the relative abundance of giraffe; their diet preference and the potential reasons for this preference. Using both spoor and dung counts as indicators of giraffe presence, transects were carried out over approximately 20 km of the Auob River. Percentage occurrence was plotted onto a map of the river, along with the location of boreholes that supply the only surface water. Little trend could be seen, although occurrence appeared slightly higher near boreholes. The two trees that most commonly occur in the Auob duneveld, Acacia erioloba and Acacia haematoxylon, were examined for nutritional content, and both chemical and physical defences - all of which are thought to affect herbivore selection. Stable isotope analysis and linear mixing model were used to determine the proportion of each species in the diet of giraffe using the leaves of both species and giraffe dung. The majority of the giraffe's diet consists of A. haematoxylon (mean = 79 %, s.d. = 20.5 %) despite having less crude protein and similar condensed tannin content. Relative lack of physical defences appears to encourage giraffes to exploit A. haematoxylon, which has shorter, weaker thorns. Without management intervention, A. haematoxylon could suffer selective mortality through the impacts of giraffe browsing, resulting in a loss of species and structural diversity of the landscape

Elephant fruit :The dispersal attributes of Balanites maughamii / Storme Viljoen

Endozoochorous plant species that have obligate dispersal mutualisms with megafauna are at risk of extinction because of the unique conservation threats associated with large animals. This study examines Balanites maughamii which appears to have similar dispersal attributes to Sclerocarya birrea and Balanites wilsoniana, both of which are considered to be obligate elephant fruits. Here, I emphasize the traits that make B. maughamii suitable for elephant dispersal and examine the cues required for seed germination. Large, fleshy fruits with a single, exceptionally hard seed which requires a crushing force of > 2.0 kN to promote germination are characteristic of this species. Using scent analysis of ripe fruits, the range of volatile that are responsible for the pungent odour were identified as being those which should function in mammal-attraction. Finally I examine the potential for long-distance dispersal by elephants using a gut passage time experiment, which revealed that elephants retain seed for approximately 48 hours, equating to a 4-8 km dispersal distance. Using fruit and seed bait stations to determine which other animals interact with B. maughamii, I found that small mammals may play a significant role in seed predation and that there is little evidence to suggest extensive secondary dispersal by rodents. These finding allude to the vulnerability of the long-term maintenance of B. maughamii in the absence of elephants, who appear to be their only legitimate disperser

Feeding choices and impacts of extralimital giraffe on two keystone tree species in the Kgalagadi National Park

In this article we determine the effect of an extralimital megaherbivore on the reproductive potential and vegetation structure of two keystone tree species in the Auob River in the south western Kalahari Desert of southern Africa. Using spoor and dung counts we establish the presence of giraffe in three predetermined density zones by walking 50 transects across the river in each zone. We also photographed six trees from each species in each zone and use these photographs to determine browse impact on reproductive potential, canopy volume as well as the percentage dieback on the extremities of the canopy. We then perform stable carbon and nitrogen isotope analysis on the leaves of the trees and compare these relative to the isotope ratios of giraffe dung to ascertain dietary preference. Crude protein was determined as a guide to nutritive value. Finally, we determine both chemical and physical defences for the two species. Our results show a significant negative impact of giraffe browse on tree canopies, no significant differences in recruitment and a noticeable decrease in flowers and pods at the giraffe browse height of 2 m – 5 m. No significant differences in crude protein or condensed tannins were found but significant differences in spinescence. Giraffe are not endemic to the Auob River and our study shows that the introduction of these animals is having a negative impact on the canopies of Vachellia haematoxylon. While there are, as yet, no significant impacts on reproductive potential we speculate that this will happen with time. Conservation implications: Our study shows that giraffe are significantly impacting the canopies of two common tree species in the Auob River in the arid Kgalagadi Transfrontier Park. Without management intervention an increasing population of giraffe will result in substantial changes to the plant community vegetation structure of the river

Molecular detection of tick-borne pathogens in caracals (Caracal caracal) living in human-modified landscapes of South Africa

Background: Wild carnivores living alongside humans and domestic animals are vulnerable to changes in the infectious disease dynamics in their populations. The aims of this study were to determine the prevalence and diversity of selected tick-borne pathogens (TBPs) of veterinary and/or zoonotic concern in wild populations of caracals (Caracal caracal) occurring in human-modified landscapes in South Africa. Using molecular techniques, we screened 57 caracal blood samples for infection by rickettsial bacteria and piroplasms in three regions of South Africa: rangeland in the Central Karoo (n = 27) and Namaqualand (n = 14) as well as the urban edge of the Cape Peninsula (n = 16) of South Africa. To characterise pathogen identity, we sequenced the 18S rRNA and 16S rRNA genes from positive samples and analysed sequences within a phylogenetic framework. We also examine the diversity of potential tick vectors. Results: All individuals tested were infected with at least one tick-borne pathogen. Pathogens included Hepatozoon felis, Babesia felis, Babesia leo and a potentially novel Babesia species. An Anaplasma species previously described in South African domestic dogs was also found in 88% of urban edge caracals. Higher rates of co-infection characterised urban edge caracals (81% vs 15% and 0% in the two rangeland populations), as well as a greater incidence of mixed infections. Host attached tick species include Haemaphysalis elliptica, an important pathogen vector among carnivore hosts. Conclusions: This study confirms the occurrence of previously undocumented tick-borne pathogens infecting free-ranging caracals in human-modified landscapes. We identify clear differences in the pathogen profiles among our study populations and discuss the likely health costs to caracals living adjacent to urban areas.Arts and Sciences, Irving K. Barber School of (Okanagan)Non UBCBiology, Department of (Okanagan)ReviewedFacult