Although disease outbreaks in wildlife populations can cause direct mortality and changes in behavior due to active infection, little is known about indirect effects on animal behavior after an outbreak. Changes in animal behavior after a disease outbreak might even be more striking for group-living animals, as contacts between groups might either increase or decrease due to disruption of the social status quo. Because direct contacts between groups are notoriously difficult to quantify for wildlife, the potential for inter-group contacts is often measured by the degree of overlapping space use between groups. Here we utilize two long term datasets on social carnivores, African lions (Panthera leo) and wolves (Canis lupus), to ask how contact networks change in the face of canine distemper virus (CDV) outbreaks. Specifically, we utilize serology and locational data (VHF and GPS) from Serengeti lions and Yellowstone wolves to: 1) describe the contact networks between groups in each population over time; 2) ask if disease outbreaks explain any temporal fluctuation in the contact networks; and 3) estimate whether any associated changes dampen or inflate the spread of subsequent outbreaks.
Results/Conclusions
Serengeti lion pride territory overlap decreased after a lethal 1993-4 CDV outbreak killed one third of the lion population. In preliminary results, lion contact networks were not only more disconnected during and after the lethal epidemic, but also were more disconnected during and after a non-lethal 1981 CDV outbreak. Our machine learning model predicted that, after controlling for pride effect (e.g., prides on the plains are always less connected due to lower density of lions in the low quality habitat), year was the best predictor of contacts between groups; pride connectivity was lowest during the CDV epidemic years and in the following 2 year periods. We see similar trends in Yellowstone wolves, with packs becoming less connected during a 2005 CDV outbreak. Our results highlight the complexity of disease dynamics in social species and imply that group-living animals might be quite vulnerable to large outbreaks of directly transmitted pathogens; yet, conversely, social species might also be buffered in the short term post-outbreak.