Jorgelina Marino

Low-coverage vaccination strategies for the conservation of endangered species

The conventional objective of vaccination programmes is to eliminate infection by reducing the reproduction number of an infectious agent to less than one, which generally requires vaccination of the majority of individuals. In populations of endangered wildlife, the intervention required to deliver such coverage can be undesirable and impractical; however, endangered populations are increasingly threatened by outbreaks of infectious disease for which effective vaccines exist. As an alternative, wildlife epidemiologists could adopt a vaccination strategy that protects a population from the consequences of only the largest outbreaks of disease. Here we provide a successful example of this strategy in the Ethiopian wolf, the worlds rarest canid, which persists in small subpopulations threatened by repeated outbreaks of rabies introduced by domestic dogs. On the basis of data from past outbreaks, we propose an approach that controls the spread of disease through habitat corridors between subpopulations and that requires only low vaccination coverage. This approach reduces the extent of rabies outbreaks and should significantly enhance the long-term persistence of the population. Our study shows that vaccination used to enhance metapopulation persistence through elimination of the largest outbreaks of disease requires lower coverage than the conventional objective of reducing the reproduction number of an infectious agent to less than one.

The effect of the last glacial age on speciation and population genetic structure of the endangered Ethiopian wolf ( Canis simensis )

During the last glacial age, Afro‐alpine habitats were widespread across the highlands of Ethiopia. A wolf‐like canid ancestor is thought to have colonized this expanding habitat and given rise to a new species that was remarkably well adapted to the high altitude environment: the Ethiopian wolf Canis simensis. Here, we address the timing of genetic divergence and examine population genetic history and structure by investigating the distribution of mitochondrial DNA (mtDNA) sequence variation. The pattern of mtDNA variation and geographical distribution indicate an initial population expansion, probably immediately after divergence from the wolf‐like ancestor, around 100 000 years ago. The partition of mtDNA haplotypes that followed was most likely the result of habitat reduction and fragmentation at the onset of deglaciation ~ 15 000 years ago. Phylogenetic and geographical associations suggest that the most likely genetic partitioning corresponds to three mountain areas, Arsi/Bale, Wollo/Shoa and Simien/Mt. Guna. Although there is a degree of clustering of haplotypes from both sides of the Rift Valley, the lack of reciprocal monophyly does not support the taxonomic classification of two subspecies. This study highlights the importance of populations north of the Rift Valley for the maintenance of genetic variability within the species and has consequent implications for conservation.

Threatened Ethiopian wolves persist in small isolated Afroalpine enclaves

The Ethiopian wolf Canis simensis is endemic to the Afroalpine highlands of Ethiopia. Half of the world population, estimated at c . 500 individuals, lives in the Bale Mountains of southern Ethiopia. Little is known, however, about the presence of wolves and suitable habitat in other Afroalpine ranges. Assessing the distribution, abundance and threats to all extant populations is a conservation priority for this Critically Endangered canid. With these objectives in mind, surveys were conducted between 1997 and 2000 in the little known regions of Arsi, Wollo, Gondar and Shoa. Suitable habitat and resident wolves were found in all regions. Outside Bale the existence of six other isolated populations, including two previously undescribed, was confirmed. All were small, estimated at no more than 50 individuals, and some with in situ conservation actions to be expanded to other regions of the Ethiopian highlands.

Canine distemper in endangered Ethiopian wolves.

Investigation into mortalities within endangered species can direct conservation efforts.

Diet of Four Sympatric Carnivores in Savé Valley Conservancy, Zimbabwe: Implications for Conservation of the African Wild Dog (Lycaon pictus)

Most populations of wild dogs (Lycaon pictus) are declining across southern and southeastern Africa, and in the Savé Valley Conservancy (SVC) the decline appears to be associated with declining populations of prey and increasing numbers of competitors. Identifying the threats to this wild dog population is currently needed to determine the most appropriate conservation actions. We studied the diet composition, breadth and overlap among four sympatric carnivores in SVC: African wild dog, spotted hyaena (Crocuta crocuta), lion (Panthera leo) and leopard (Panthera pardus), using faecal analysis. We found remains of 16 mammalian prey species, ranging from small to large mammals (2–525 kg). The four carnivores had many prey species in common (>70% diet overlap), with impala (Aepyceros melampus) consistently the most frequent. The frequency of occurrence of impala, however, was highest in the diets of wild dogs (74%), and wild dogs were found to have the narrowest standardized dietary niche breadth (0.087). The diets also varied significantly in the contribution of different prey-size categories, with large prey (>100 kg) contributing most to the diets of lions and hyaenas, and small prey (<5 kg) to the diet of leopards. With impala populations in decline, competition for prey can explain the observed decline in the less competitive and more specialized wild dog, whose main food resource is shared with a rapidly increasing population of spotted hyaenas and lions in the SVC.

Ecological bases of philopatry and cooperation in Ethiopian wolves

Ecological reasons for philopatry and cooperation are frequently invoked when kin selection is an insufficient explanation. The Ethiopian wolf (Canis simensis) is a specialised rodent hunter that forms family groups with cooperative breeding but also lives as monogamous pairs in suboptimal areas. Given the apparent absence of fitness gains to helpers from cooperative breeding, we set out to explore the benefits accrued by communal territorial defence measured as the acquisition and retention of habitats with more and most preferred rodent prey. Pairs defended relatively large territories to encompass critical amounts of key habitats within a matrix poor in rodents. Groups in optimal areas had relatively small territories and were expansionist, such that wolves in larger packs benefited per capita from increased good-quality foraging habitat. The fitness benefits of philopatry became evident after a rabies epizootic, when philopatry and expansionism prevailed in under-saturated conditions, until large groups split or provided dispersers that established locally. This study shows that high concentrations of prey can shift the balance of costs and benefits towards group living and cooperation in long-lived territorial carnivores, in so far as this dictates immediate rewards accrued from a given increment in territory size, namely greater foraging area per animal, leading to group enlargement and eventual inheritance of breeding space.

Feasibility and efficacy of oral rabies vaccine SAG2 in endangered Ethiopian wolves

Diseases are a major cause of population declines in endangered populations of several canid species. Parenteral vaccination efforts to protect Ethiopian wolves (Canis simensis) from rabies have targeted the domestic dog reservoir, or the wolves themselves in response to confirmed outbreaks. Oral vaccination offers a more cost-efficient, safe and proactive approach to protect Ethiopian wolves and other threatened canids from rabies. Field trials of the oral vaccine Rabigen® SAG2Dog were undertaken in the Bale Mountains of southeastern Ethiopia. Four different bait types and three delivery methods were tested in twelve Ethiopian wolf packs, and the oral vaccine (using the preferred bait) was trialled in three packs. Vaccine uptake and immunization rates were measured through direct observations and in live-trapped animals through the assessment of biomarker levels and serological status. Commercial baits were never taken by wolves; goat meat baits had the highest uptake, compared to rodent and intestine baits. Targeted delivery from horseback and nocturnal delivery within a packs territory performed favourably compared to random bait distribution. Bait uptake by non-target species was lowest during the nocturnal blind distribution. Of 21 wolves trapped after vaccination, 14 were positive for the biomarker iophenoxic acid (i.e. ingested the bait and most likely pierced the sachet with the vaccine). Of these, 86% (n=12/14) had levels considered sufficient to provide protective immunity to wildlife (⩾0.20IU/ml), and 50% (n=7/14) demonstrated antibody titres above the universally recognised threshold (⩾0.5IU/ml) -the baseline average was 0.09IU/ml (n=12 wolves). All but one of the wolves vaccinated in 2014 were alive 14months later. Our trials confirm the potential for SAG2, delivered in a goat meat bait, to effectively protect Ethiopian wolves against rabies, supporting the initiative for a more efficient and proactive approach to manage and eventually eliminate rabies in Ethiopian wolf populations.

Predicting Hotspots of Human-Elephant Conflict to Inform Mitigation Strategies in Xishuangbanna, Southwest China.

Research on the spatial patterns of human-wildlife conflict is fundamental to understanding the mechanisms underlying it and to identifying opportunities for mitigation. In the state of Xishuangbanna, containing China’s largest tropical forest, an imbalance between nature conservation and economic development has led to increasing conflicts between humans and Asian elephants (Elephas maximus), as both elephant numbers and conversion of habitable land to rubber plantations have increased over the last several decades. We analyzed government data on the compensation costs of elephant-caused damage in Xishuangbanna between 2008 and 2012 to understand the spatial and temporal patterns of conflict, in terms of their occurrence, frequency and distribution. More than 18,261 incidents were reported, including episodes involving damage to rubber trees (n = 10,999), damage to crops such as paddy, upland rice, corn, bananas and sugarcane (n = 11,020), property loss (n = 689) and attacks on humans (n = 19). The conflict data reconfirmed the presence of elephants in areas which have lacked records since the late 1990s. Zero Altered Negative Binomial models revealed that the risk of damage to crops and plantations increased with proximity to protected areas, increasing distance from roads, and lower settlement density. The patterns were constant across seasons and types of crop damaged. Damage to rubber trees was essentially incidental as elephants searched for crops to eat. A predictive map of risks revealed hotspots of conflict within and around protected areas, the last refuges for elephants in the region, and along habitat corridors connecting them. Additionally, we analyzed how mitigation efforts can best diminish the risk of conflict while minimizing financial costs and adverse biological impacts. Our analytical approach can be adopted, adjusted and expanded to other areas with historical records of human-wildlife conflict.

Where buffalo and cattle meet: modelling interspecific contact risk using cumulative resistant kernels

African buffalo the primary source of foot and mouth disease (FMD) infection for livestock in South Africa. Predicting the spatial drivers and patterns of buffalo–cattle contact risk is crucial for developing effective FMD mitigation strategies. Therefore, the goal of this study was to predict fine-scale, seasonal contact risk between cattle and buffaloes straying into communal lands adjacent to Kruger National Park. This study provides the first application of the cumulative resistant kernel method to calculate contact risk between two species. We built resistance surfaces from resource utilization models of buffalo and cattle and calculated the intersection of resistant kernels of the two species. This revealed that the contact risk is influenced by seasonality, water sources and fence strength, and the magnitude of contact risk is largely driven by buffalo and cattle dispersal abilities. The probability of contact was higher in the dry season, with hotspots along a main river and the weakest parts of the perimeter fence. In the wet season, contact risk was more diffuse and less concentrated along the main river and near settlements. The new approach of intersecting cumulative resistant kernels of two species can produce quantitative predictive maps of animals’ contact risk and help identify potential hotspots of disease transmission.

Going to the Dogs: Free-Ranging Domestic Dogs Threaten an Endangered Wild Canid through Competitive Interactions

Domestic dogs threaten wildlife globally, especially other canids. The spread of infectious disease from dogs threatens Ethiopian wolves, via interference and exploitation competition. Despite increasing threats to wildlife from dogs, competition between dogs and wild carnivores is relatively unstudied. This study seeks to understand the behavior and habitat use of free-ranging dogs in the Bale Mountains National Park, Ethiopia, and their interactions with other park users, through focal animal follows totaling > 150 hours. Dogs used the same areas as wolves, foraged throughout wolf habitat, and aggressively interacted with wolves in their territories. Wolves were actively displaced from foraging grounds by dogs, with dogs chasing wolves both while foraging alone or when moving with livestock. Direct competition for small mammals was not sustained by these results. Female dogs may make less extensive use of wolf range; they covered significantly less distance and interacted less aggressively with wolves. Domestic dogs are increasingly present in protected areas around the globe, and this study documents their negative impact on wild carnivores—both through direct interaction and use of habitat – highlighting the implications of dog presence for wildlife conservation.