PARENT SESSION
Contributed Oral Session 44: Mammal Ecology: Seals, Deer, and Bats
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 518 C, Level 5, Palais des congrès de Montréal
Effects of winter severity, infectious diseases and individual characteristics on the survival of hibernating carnivores: a case study with striped skunks and rabies in a northern environment.
Hwang, Yeen Ten*,1, Lariviere, Serge2, Messier, Francois1, 1 University of Saskatchewan, Saskatoon, Saskatchewan, Canada2 Fédération des Trappeurs Gestionnaires du Québec, Sainte-Foy, Quebec, Canada
ABSTRACT- Dynamics of animal populations are influenced by extrinsic environmental variables (e.g. climate, food resources, diseases, and predation) and intrinsic individual characteristics (e.g. age, gender, and body condition). These variables can either act independently or interactively to influence the survival and reproduction of animals. We investigated the interactive effects of winter severity, disease, and individual characteristics on the survival of striped skunks in the Canadian prairie from 2000 to 2003. The study coincided with the outset of a major rabies outbreak in 1999 and 2000, and lasted through its gradual recovery during 2001, 2002, and 2003. We hypothesized that survival during winter (September to March − 190 days) is affected simultaneously by winter severity, rabies, and body condition, and also that survival during summer (April to July − 122 days) is influenced mainly by gender effects, but not by body condition. We used a multivariate Cox proportional hazards model to examine the interactive effects of our test variables on the survival of individual skunks in this population. A total of 99 skunks (43 males, 56 females) were monitored by radio-tracking during four consecutive winters (2000-2003). We also radio-tracked 48 skunks (14 males, 34 females) during three consecutive summers (2001-2003). Our results clearly highlight the influence of winter severity and rabies on the winter survival of striped skunks. Specifically, mortality increases with winter severity, and the effects of rabies are amplified when winter is severe, however, at a certain threshold of body condition, winter survival is high regardless of winter condition. Winter conditions significantly reduces survival of skunks, irrespective of gender and age. In contrast, summer survival is independent of body condition, but highly dependent on gender, with female skunks experiencing greater mortality. This study of extrinsic and intrinsic effects on the population dynamics could elucidate the link between climate and biogeography of species that undergo winter inactivity.−
Key words: Cox proportional hazards model, Seasonal survival, Extrinsic and intrinsic variables, small carnivore