CHEYENNE, Wyo. (AP) — A new study says wolves don't startle female elk that winter east of Yellowstone National Park sufficiently to make them lose weight or harm their birthing rates.

Previous researchers theorized that Yellowstone-area wolves frighten female elk into running frequently enough to reduce their ability to stay healthy and reproduce.

Researcher Arthur Middleton and others who monitored wolves and elk in the Cody area over three winters say in a study released Tuesday they don't see that happening.

Rather, they say elk don't move much until wolves are relatively close by — within a half-mile or so. Such close encounters happen relatively infrequently — every nine days or so.

The researchers say summer forage conditions have a bigger effect on elk health.

They published their findings in the journal Ecology Letters.