High stress in heavily hunted wolves
by Cat Urbigkit, Pinedale Online!
November 12, 2014
A new research paper reports on the results of an examination of stress and reproductive hormone levels in hunted populations of wolves in northern Canada. The paper, "Heavily hunted wolves have higher stress and reproductive steroids than wolves with lower hunting pressure" was published this week in the journal Functional Ecology.
Here's the summary of the research:
1. Human-caused harassment and mortality (e.g. hunting) affects many aspects of wildlife population dynamics and social structure. Little is known, however, about the social and physiological effects of hunting, which might provide valuable insights into the mechanisms by which wildlife respond to human-caused mortality.
2. To investigate physiological consequences of hunting, we measured stress and reproductive hormones in hair, which reflect endocrine activity during hair growth. Applying this novel approach, we compared steroid hormone levels in hair of wolves (Canis lupus) living in Canada's tundra–taiga (n = 103) that experience heavy rates of hunting with those in the northern boreal forest (n = 45) where hunting pressure is substantially lower.
3. The hair samples revealed that progesterone was higher in tundra–taiga wolves, possibly reflecting increased reproductive effort and social disruption in response to human-related mortality. Tundra–taiga wolves also had higher testosterone and cortisol levels, which may reflect social instability.
4. To control for habitat differences, we also measured cortisol in an out-group of boreal forest wolves (n = 30) that were killed as part of a control programme. Cortisol was higher in the boreal out-group than in our study population from the northern boreal forest.
5. Overall, our findings support the social and physiological consequences of human-caused mortality. Long-term implications of altered physiological responses should be considered in management and conservations strategies."
The researchers noted, "As predicted, wolves from heavily hunted populations had higher stress and reproductive hormone levels which probably reflect a number of environmental conditions including human-caused mortality.
The researchers also noted the difference between the wolves studied in Canada to other wolf populations in North America: "Unlike wolf populations elsewhere in North America, wolves in the tundra–taiga and northern boreal forest regions that we studied experience low levels of human activity for most of the year. However, hunting and trapping of wolves occur throughout the area in the winter months when fur is prime. In the largely roadless tundra–taiga, hunting takes place when lakes are frozen so that areas where wolves and caribou over winter can be accessed by snowmobile."
The report concluded: "The potential physiological effects of substantial, human-caused mortality suggest that hunting could be causing changes in reproductive structure and breeding strategy, as well as imposing chronic stress. Though increased reproduction might be viewed as a positive response of wolves to population reductions, the implications on lifetime reproductive output and generational survival of offspring as compared with undisturbed populations are unknown."
To read the details, click on the links below.
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