Wolves: Hunting Affects Stress, Reproduction, and Sociality
Harassed wolves show elevated levels of stress and reproductive hormones.
Posted November 12, 2014
A study just published in the journal Functional Ecology called "Heavily hunted wolves have higher stress and reproductive steroids than wolves with lower hunting pressure" by Heather Bryan, of the University of Calgary Faculty of Veterinary Medicine and a Raincoast Conservation Foundation scientist, and her colleagues shows that heavily hunted individuals show changes in reproductive behavior and that there is social disruption of their packs. The effects of hunting can have long-term consequences. A summary of this most important study can be read here.
To analyze stress levels, the research team studied hair samples from wolves living on the tundra/taiga from Nunavut and the Northwest Territories (n = 103) and wolves living in the boreal forests of Alberta and the Northwest Territories (n = 45). The wolves living on the open landscape of the tundra/taiga typically hunt caribou and are more exposed to hunting than the wolves living in the boreal forest, who hunt moose and are less harassed.
The results of this study are as follows. Females living in the open showed higher progesterone levels than female living in the forest. Bryan and her colleagues note that "When social structure is disrupted, multiple litters per social group become more common, in part because dominant individuals can no longer prevent subordinates from breeding ..." This finding is consistent with other studies. For males, "higher testosterone among tundra–taiga wolves is unlikely to reflect higher reproductive activity since hair does not grow – and therefore is unlikely to incorporate steroid hormones – during the breeding season, which occurs in winter. Instead, we propose that higher cortisol and testosterone levels in tundra–taiga wolves are consistent with social instability caused by an increased frequency of interindividual interactions that have unpredictable outcomes ...Notably, culling has been previously shown to disrupt social structure, resulting in increased dispersal and disease transmission." The results for males also are consistent with findings from other studies.
This landmark study provides "the first baseline on chronic levels of stress and reproductive hormones in wolf hair. Of great importance, the "findings highlight the importance of considering factors other than population numbers when setting management objectives." Experts agree. Paul Paquet, a Raincoast Conservation Foundation scientist and University of Victoria researcher, notes: “The effects of stress are often subtle, but the resulting harm can be acute, chronic, and permanent, sometimes spanning generations.”
Clearly, the short-term and long-term effects of the wanton harassment and killing of wolves require detailed analyses of just what these activities do to individuals and to packs. Merely counting the number of individuals who are present and then deciding how to manage them is a shoddy practice at best, and one that is not based on what scientific research has shown. Evidence based decisions -- not practices that are based on a hate for these remarkable and magnificent animals and fear mongering -- are much needed in wolf management across their range.
The teaser image can be seen here.
Marc Bekoff's latest books are Jasper's story: Saving moon bears (with Jill Robinson; see also), Ignoring nature no more: The case for compassionate conservation (see also), Why dogs hump and bees get depressed (see also), and Rewilding our hearts: Building pathways of compassion and coexistence. The Jane effect: Celebrating Jane Goodall (edited with Dale Peterson) will be published in 2015. (marcbekoff.com; @MarcBekoff)