title: Environmental and Intrinsic Correlates of Stress in Free-Ranging Wolves.
abstract: BACKGROUND
  When confronted with a stressor, animals react with several physiological and behavioral responses. Although sustained or repeated stress can result in severe deleterious physiological effects, the causes of stress in free-ranging animals are yet poorly documented. In our study, we aimed at identifying the main factors affecting stress levels in free-ranging wolves (Canis lupus).
  
  
  RESULTS
  We used fecal cortisol metabolites (FCM) as an index of stress, after validating the method for its application in wolves. We analyzed a total of 450 fecal samples from eleven wolf packs belonging to three protected populations, in Italy (Abruzzo), France (Mercantour), and the United States (Yellowstone). We collected samples during two consecutive winters in each study area. We found no relationship between FCM concentrations and age, sex or social status of individuals. At the group level, our results suggest that breeding pair permanency and the loss of pack members through processes different from dispersal may importantly impact stress levels in wolves. We measured higher FCM levels in comparatively small packs living in sympatry with a population of free-ranging dogs. Lastly, our results indicate that FCM concentrations are associated with endoparasitic infections of individuals.
  
  
  CONCLUSIONS
  In social mammals sharing strong bonds among group members, the death of one or several members of the group most likely induces important stress in the remainder of the social unit. The potential impact of social and territorial stability on stress levels should be further investigated in free-ranging populations, especially in highly social and in territorial species. As persistent or repeated stressors may facilitate or induce pathologies and physiological alterations that can affect survival and fitness, we advocate considering the potential impact of anthropogenic causes of stress in management and conservation programs regarding wolves and other wildlife.
authors.affiliation: Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Molnar
authors.affiliation: School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Julien
authors.initials: J
authors.lastname: Fattebert
authors.affiliation: Department of Biomedical Sciences/Unit of Physiology, Pathophysiology and Experimental Endocrinology, Vetmeduni, Vienna, Austria.
authors.forename: Rupert
authors.initials: R
authors.lastname: Palme
authors.affiliation: Department of Biology and Biotechnologies, University "La Sapienza", Roma, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Ciucci
authors.affiliation: Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
authors.forename: Bruno
authors.initials: B
authors.lastname: Betschart
authors.affiliation: Yellowstone Center of Resources, National Park Service, Yellowstone National Park, Wyoming, United States of America.
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Smith
authors.affiliation: Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
authors.forename: Peter-Allan
authors.initials: PA
authors.lastname: Diehl
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources; D017753:Ecosystem; D005243:Feces / Q000469:parasitology; D005260:Female; D005602:France; D006374:Helminthiasis, Animal / Q000453:epidemiology / Q000378:metabolism*; D006854:Hydrocortisone / Q000378:metabolism; D007558:Italy; D008297:Male; D012621:Seasons; D013312:Stress, Physiological; D013315:Stress, Psychological / Q000378:metabolism*; D014481:United States; D019596:Wolves / Q000378:metabolism* / Q000469:parasitology
chemical_list: D006854:Hydrocortisone