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 latest research. “What really distinguishes this paper is the fact that it focuses on selecting behavior."
Previous studies have found that 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," Ciuti says. That observation suggests that the behavior reflects the elk’s personality and is not a response to the increased presence of hunters, he says.
The next question Ciuti’s 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," Ciuti says, “and so the population would balance out over time."
The study, Fryxell says, “reaffirms something that we’ve suspected for a long time: (Humans) are exerting a strong influence on the behaviors, physiology, and life history characteristics of animals all around us."
Big cats need big habitats to roam in. Will an increasingly crowded world still have room for tigers? A field study of tigers in Nepal suggests that, in some cases, people and animals can coexist by “timesharing" the same territory.
Nepal’s Chitwan National Park, established in 1973, covers about 1,000 square kilometers and is one of only 28 reserves in the world that can support more than 25 breeding female tigers — likely the smallest number needed to maintain genetic diversity, says Neil Carter, a conservation scientist at Michigan State University. Human activity in and around the park is both diverse and widespread: Local residents collect firewood, soldiers patrol forest roads to deter poachers and other criminals, and a growing number of ecotourists visit the area each year.
The good news is that the tigers are still there. Even though the park and its vicinity harbor about twice as many people per square kilometer as other countries where tigers live, a good number of tigers inhabit the area, Carter says. To study how the two species coexist, he and his team placed motion-sensing “camera traps" along trails and roads in a study area including the northern fringe of the park.
Surprisingly, Carter notes, human presence outside the park didn’t drive the tigers into the park’s wilderness: The density of tigers inside and just outside the park was not significantly different. And overall tiger numbers in the park didn’t drop when more humans were around.
Nevertheless, the team’s analyses show that tigers were more likely to be found at sites away from human settlement, the researchers reported last week in the Proceedings of the National Academy of Sciences. The team also found that the tigers in and around Chitwan park were much more likely to be active at night than tigers living elsewhere.
“Tigers don’t like to go around where people are," says John Seidensticker, a conservation scientist at the Smithsonian Institution’s National Zoological Park in Washington. Nevertheless, he adds, “Nepal has been good at working out ways for people and tigers to get along successfully."
Timesharing the environment might not work well with many threatened species or in many areas: Think of the attitudes against bears, cougars and wolves in the United States. However, Carter and his colleagues contend, the notion of humans and endangered animals sharing terrain by shifting their behavior — and particularly by shifting when each species uses the habitat — should be incorporated into conservation plans when it makes sense.