|Grey wolf in Yellowstone National Park, USA|
It was found that the coyotes presented a great health risk to the wolves, transmitting diseases such as the canine parvovirus to wild-born wolves. Moreover other conditions emerged after the reintroduction of the wolves, such as mite infections and canine distemper. These health risks can interfere with the growth of the population of grey wolves in Yellowstone. However it seems that the population of grey wolves is stable and thriving, much due to the efforts in protecting and monitoring infectious diseases in Yellowstone.
“The protection of Yellowstone that has afforded the wolf reintroduction effort such great success has also allowed us to watch the natural transition from population growth to limitation or regulation, in which parasites appear to play a significant role.”
-Almberg, E. S. et al. 2012
"Wildlife reintroductions select or treat individuals for good health with the expectation that these individuals will fare better than infected animals. However, these individuals, new to their environment, may also be particularly susceptible to circulating infections and this may result in high morbidity and mortality, potentially jeopardizing the goals of recovery. Here, using the reintroduction of the grey wolf (Canis lupus) into Yellowstone National Park as a case study, we address the question of how parasites invade a reintroduced population and consider the impact of these invasions on population performance. We find that several viral parasites rapidly invaded the population inside the park, likely via spillover from resident canid species, and we contrast these with the slower invasion of sarcoptic mange, caused by the mite Sarcoptes scabiei. The spatio-temporal patterns of mange invasion were largely consistent with patterns of host connectivity and density, and we demonstrate that the area of highest resource quality, supporting the greatest density of wolves, is also the region that appears most susceptible to repeated disease invasion and parasite-induced declines. The success of wolf reintroduction appears not to have been jeopardized by infectious disease, but now shows signs of regulation or limitation modulated by parasites."