Managed hunting can help maintain animal populations

May 21, 2018, University of Cambridge

Researchers studying the hunting of ibex in Switzerland over the past 40 years have shown how hunts, when tightly monitored, can help maintain animal populations at optimal levels.

The international team of researchers, led by the University of Cambridge and the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), studied the hunt of Alpine ibex – a type of wild goat with long, curved horns – in the eastern Swiss canton of Graubünden by examining the horn size of more than 8,000 ibex harvested between 1978 and 2013, to determine whether average horn growth or body weight had changed over the last 40 years.

Their results, published in the Journal of Animal Ecology, reveal that unsurprisingly, ibex with longer-than-average horns are more likely to be shot than animals of the same age with shorter horns. However, due to tight controls placed on the hunt by the Swiss authorities, hunters tend to shoot as few animals as possible, to avoid violating the rules and incurring large fines.

Hunting for specific traits can place selective pressure on certain species, resulting in a negative evolutionary response. In their study, the researchers investigated whether the targeting of ibex with large horns would lead to a lower average horn size across the entire population.

They found that while even tightly-managed hunts cannot prevent hunters from targeting longer-horned animals, no long-term changes were found in the horn length of male ibex in Graubünden, which is most likely related to the fact that the numbers of ibex removed from the population by hunters is too small to have an evolutionary effect.

"Our most important finding is that ibex hunting over the last 40 years has not had a negative effect on the constitution of the animals," said WSL's Kurt Bollmann, the study's senior author.

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