To run or to hide? For an elk trying to avoid a gun-wielding hunter, the choice depends on personality. Gutsy, bold elk are more likely to sprint faster and farther when they encounter a threat. Others shy away from danger in the first place, shunning human-frequented areas and exploring new places less often.
Human hunters more often kill animals that fall into the bolder group, new research has found. And this tendency could put evolutionary pressure on elk populations to become more skittish, the scientists hypothesize.
"There has been a lot of work in the past on humans selecting for appearance of animals," says biologist John Fryxell of the University of Guelph in Canada, who was not involved in the study. "What really distinguishes this paper is the fact that it focuses on selecting behavior."
Previous studies found hunters are most likely to target animals that are the biggest or have the largest antlers.
To test whether hunting also selected for elk with certain behavioral traits, researchers led by biologist Simone Ciuti of the University of Alberta in Edmonton, put GPS collars on 122 male and female elk (Cervus elaphus) in the Canadian Rockies and monitored their movement throughout the year. By the end of hunting season, 25 elk had been killed by hunters. The researchers analyzed the GPS data to determine whether the way elk move correlated with whether they'd been killed.
Hunters, they found, typically picked the elk that moved more often and traveled longer distances and that were more likely to spend time in open areas. The trend was particularly noticeable for male elk, which had larger variation in their movement patterns. The researchers found much less difference in movement patterns between the killed and nonkilled females.
"What was surprising was that the differences in habitat selection and movement rate among the elk were already present long before the start of hunting season," Mr. Ciuti says.
That observation suggests the behavior reflects the elk's personality and is not a response to the increased presence of hunters, he says. The researchers published their results online Tuesday in the Proceedings of the Royal Society B. The next question his team plans to ask is whether bold elk are more likely to be killed by other predators, such as wolves and bears.
"Bolder individuals could have an advantage over some of these other natural predators," Mr. Ciuti says, "and so the population would balance out over time."
Mr. Fryxell calls the paper topical and interesting but says that more fieldwork and additional modeling are needed to rule out other factors that could influence movement patterns, such as age and previous experiences. A good test, he says, would be whether the researchers could use their findings to predict the probability of an animal being killed in any given year.
"Overall, it reaffirms something that we've suspected for a long time," Mr. Fryxell says. "Humans are exerting a strong influence on the behaviors, physiology, and life history characteristics of animals all around us."