JACKSON, Wyo. (AP) — Research shows wolves in the northern part of Grand Teton National Park have an appetite for moose during the wintertime.

Park and U.S. Fish and Wildlife Service researchers documented some 55 moose killed by wolves over the past three winters.

The Associate Press reports moose numbers have been declining in Jackson Hole for years. The moose population is less than one-fifth the number counted 20 years ago and only about one-fourth of the number that wildlife managers would like to see.

Grand Teton biologist Sarah Dewey says wolves typically prefer to prey on elk rather than moose. Moose are bigger and she says elk are easier for wolves to take down. Other threats to moose in Grand Teton include parasites, wildfires and getting hit by cars.