July 18, 2009

Elk declining when they live near wolves

Elk in the Greater Yellowstone Ecosystem are starving due to fear of wolves and are not being killed by them, Montana State University researchers said.

Essentially, they are slowly starving, Scott Creel, an ecology professor at MCU, and lead author of the study, said. Despite grazing and browsing during the winter, elk suffer a net loss of weight.

Creel said the elk are eating in forested areas where they are safer. This browsing on woody shrubs or low tree branches provides good quality food, but the elk are taking in 27 percent less food than elk that graze in open meadows in areas without wolves.

The researchers also found a lower birth rate among elk in areas with wolves. They found lower levels of progesterone in the elk in areas with wolves.

The elk are trading reproduction for longevity, Creel said in a press release. Elk are potentially long-lived, and many prior studies have shown that, in species like this, natural selection favors individuals who do not compromise their own survival for the sake of a single reproductive opportunity.