By Brian Owens
As female elk get older, they also get wiser: they learn how to avoid getting shot by hunters, and appear to adapt their behaviour to the types of weapon the hunters carry.
Hunting by humans is known to affect how elk behave, selecting for more cautious behaviours by killing more of the bolder animals. But ecologist Henrik Thurfjell at the University of Alberta, Canada, wondered whether the animals might also learn how to stay safe as they age.
Thurfjell and his colleagues put GPS tracking collars on 49 female elk in western Canada, and monitored their behaviour over six years. They found that this varied between elk of different ages.
Those aged 4 were more cautious than 2-year-olds, for example, but that was not simply a case of all naturally bold elk being killed at an early age. Over time, the younger elk started acting more like their cautious elders, moving around less during the hunting season and making more use of dense forest or steep, rocky terrain, especially when near roads.
In fact, they became so good at avoiding humans that by the time they reached the age of 9, they were almost immune to hunting, says Thurfjell. “It’s remarkable how bulletproof they become around age 8 or 9,” he says.
Bows or rifles?
Older elk were even able to distinguish whether hunters used bows or guns, and altered their behaviour accordingly.
During bow season, they used difficult terrain more – making things tricky for bow hunters, who need to get much closer to their prey than those who use rifles. And during rifle season, the elk stayed further away from roads, where hunters might spot them.
Rather than the elk keeping track of the seasons, Thurfjell thinks this was a reaction to the behaviour of hunters. During rifle season, for instance, there may be more slow-moving vehicles on the roads.
Nadège Bonnot, an ecologist at the Swedish University of Agricultural Sciences in Uppsala, agrees that the combination of human selection and learning could have major effects on elk behaviour. By eliminating some behavioural traits, and by modifying the behaviour of survivors, “this has a large potential to impoverish behavioural variability”, she says.
But it could also select for more flexible animals that are able to quickly adapt to new threats, she adds.
Thurfjell says the elk’s ability to learn could help with wildlife management. A small amount of hunting pressure near agricultural land could quickly teach the animals to stay away, reducing crop damage and culls of nuisance animals. “Cooperation between hunters and landowners could get good results for everyone, including the elk,” he says.
Journal reference: PLoS ONE, DOI: 10.1371/journal.pone.0178082