Abstract
The disappearance of an endangered African wild dog population from Serengeti National Park (SNP) led to international debate centered around one question: were researchers to blame? The “Burrows' hypothesis” postulated that stress induced by research‐related immobilization and handling reactivated a latent rabies virus, eliminating the population. Insufficient data inhibited hypothesis testing, but since wild dogs persisted alongside SNP and have been studied since 2005, the hypothesis can be tested 25 years after its proposition. To be supported, wild dog immobilization interventions should have resulted in high mortality rates. However, 87.6% of 121 handled wild dogs (2006–2016) survived >12 months post‐handling. Some argued that viral reactivation would necessitate long‐term stress. Following immobilization, 67 animals were captured, transported, and held in a translocation enclosure. Despite the longer‐term stress, 95.5% survived >12 months. Furthermore, the stable number of wild dog packs in the ecosystem over the past decade, and lack of recolonization of SNP, strongly oppose Burrows' hypothesis. Instead, factors such as heightened levels of interspecific competition are likely to have contributed to the wild dog disappearance and subsequent avoidance of the Serengeti plains. Handling and radio telemetry are invaluable when studying elusive endangered species, yielding information pertinent to their conservation and management, and had no effect on Serengeti wild dog survival.
Highlights
Large carnivores have suffered significant global population declines, and protected areas are becoming increasingly important for their continued survival in the face of anthropogenic threats (Bauer et al, 2015; Riggio et al, 2013; Ripple et al, 2014)
Contact with domestic dogs increases exposure to rabies (Woodroffe et al, 2012) and rates of exposure are ex‐ pected to be at least the same or higher than those experienced 20 to 30 years ago in Serengeti National Park (SNP). This is because (a) the domestic dog popu‐ lation, a reservoir host for rabies (Lembo et al, 2008), has increased in size (Craft et al, 2017), with an annual growth rate of up to 8% in certain parts of the ecosystem (Czupryna et al, 2016) and (b) the surviving wild dog population occurs sympatrically with domestic dogs, and it is reasonable to assume that the current wild dog population has even greater rates of exposure to the rabies virus than the portion of the wild dog population formally resident within SNP, which is almost entirely free of domestic dogs
We assessed whether there had been any recolonization of wild dogs in SNP because if researcher intervention alone was responsible for the disappearance of wild dogs on the Serengeti plains, recolo‐ nization over the past 25 years would have been probable given the persistence of numerous wild dog packs immediately alongside the former study area and the cessation of wild dog research within SNP
Summary
Large carnivores have suffered significant global population declines, and protected areas are becoming increasingly important for their continued survival in the face of anthropogenic threats (Bauer et al, 2015; Riggio et al, 2013; Ripple et al, 2014). A controversial hy‐ pothesis implicated researchers and their handling of wild dogs as the driver of the extinction Prior to their demise, serum samples showed that some of the population had been exposed to rabies and certain animals had significant rabies‐neutralizing antibody titers. Researchers found no evidence of handling‐induced mortality in other eco‐ systems (Ginsberg, Alexander, et al, 1995), yet the proponents of Burrows’ hypothesis discredited such studies, stating that “If inter‐ vention caused immunosuppression and increased disease‐medi‐ ated mortality among adult pack members, logically any test of this idea should be conducted on data from ecosystems where (a) wild dogs contact pathogens that are lethal to adults; (b) rates of exposure to lethal pathogens are similar to that for rabies in the Serengeti; (c) types and levels of interventions sustained by packs are similar to those applied in the Serengeti” (East et al, 1997). We assessed whether there had been any recolonization of wild dogs in SNP because if researcher intervention alone was responsible for the disappearance of wild dogs on the Serengeti plains, recolo‐ nization over the past 25 years would have been probable given the persistence of numerous wild dog packs immediately alongside the former study area and the cessation of wild dog research within SNP
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