Bovine tuberculosis of the African Buffalo in Kruger National Park.
Project: Paul Cross' dissertation work at UC Berkeley.
Funding Sources: NSF-NIH Ecology Infectious Disease Program. Awarded to Wayne Getz (UC Berkeley)
Collaborators: Wayne Getz (UC Berkeley), Jamie Lloyd-Smith (now at UCLA), Sadie Ryan (NCEAS), South African National Parks, and the Mammal Research Institute at the University of Pretoria.
As a graduate student I ran a large field project on bovine tuberculosis in the African buffalo of Kruger National Park from 1999-2006. We tracked over 170 radio-collared buffalo for 6 years repeatedly testing known individuals for bovine tuberculosis to determine the effects of this new disease on the African buffalo population of Kruger National Park. These movement data are now publically available on MoveBank (http://www.movebank.org/). Despite an intensive field effort, we were unable to detect a major effect of bovine tuberculosis on the survival or reproduction of African buffalo at either the individual or population levels (Cross, 2009). This study highlights many of the challenges associated with detecting the impacts of chronic diseases on wildlife populations. We did find, however, that body condition decreased more rapidly during the dry season in herds with a high prevalence of bovine tuberculosis (Caron, 2003). Our work assisted managers in looking at not only buffalo, but other spill-over species for which there were few data (Michel, 2006).
We completed several other applied studies. First, we found no evidence of any delayed mortality or reproduction effects in over 880 helicopter and ground captures (Oosthuizen, 2009). Using simulation models we showed how vaccination programs were unlikely to be effective (Cross, 2006). We also found that the previous perception of stable buffalo herds did not apply to the Kruger population and that previous statistical approaches of association patterns were inaccurate in some circumstances due to autocorrelation (Cross, 2005).
Few studies of sexual segregation have directly estimated death rates in different social environments, and our research showed that males trade predation-risk for better foraging and body condition in male-only groups (Hay, 2008). Using remote-sensing data we showed that buffalo responses to habitat quality are context-dependent, whereby in poorer quality habitats buffalo became more selective (Winnie, 2008).
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