Finding patterns in wildlife attacks on domestic livestock

Lynx in the Bavarian Forest Nature Park, Germany. Image credit, Aconcagua.When carnivorous wildlife prey on agricultural livestock, it can make a conservationist's job very difficult. Farmers looking to limit their losses can try to kill predators themselves or exert political pressure for policies of lethal control.

A new study in the Journal of Applied Ecology tries to address this problem by looking at patterns of livestock predation by brown bears (Ursus arctos), wolves (Canis lupus), and lynx (Lynx lynx) in south-central Sweden.

Researchers Jens Karlsson and Orjan Johansson found that when it comes to killing sheep on specific farms, predatory wildlife tend to be repeat offenders - particularly within the first five weeks of the attack. Farms that already had been subject to a predation event were 50 times more likely than other properties to have sheep killed again by wildlife. This risk of repeat attack was greatest immediately after the initial event and then declined over time.

Approximately 30% of the repeat attacks occurred within the first week after the initial predation event and 60% occurred within five weeks. The authors suspect that the repeat attacks occur because predators return to the site for carrion.They doubt the pattern of repeat attacks occur because the farms are located in hotspots or they employ husbandry techniques that the put the animals at risk. If that were the case, the risk of a repeat attacks would likely be more evenly distributed over the subsequent 12 months following the initial occurrence.

The information in this study can help managers adopt non-lethal proactive measures to minimize wildlife attacks on livestock. The authors write,

"As the risk of a repeat attack decreases rapidly over the first 5 weeks after the initial attack, it may be possible to reduce livestock predation by using simple, low budget solutions such as, for example, scaring devices, keeping livestock inside barns, smaller pastures with improved fencing, increased herding effort or changing the grazing area used by free roaming livestock."

This could be particularly helpful in poorer countries that do not have the economic resources to compensate landowners for livestock deaths from wildlife. In the U.S. and Europe such programs have helped address the conflict between wildlife conservation and livestock predation somewhat.

--Reviewed by Rob Goldstein

Karlsson, J., & Johansson, O. (2009). Predictability of repeated carnivore attacks on livestock favours reactive use of mitigation measures Journal of Applied Ecology DOI: 10.1111/j.1365-2664.2009.01747.x