ANCHORAGE, Alaska (AP) — A large decline in wolves inside one of Alaska’s national preserves is coinciding with a state-sanctioned program to kill the animals near the boundaries of Yukon-Charley Rivers National Preserve, a National Park Service official said Friday.

Federal biologists discovered a more than 50 percent decline, the highest on record, by comparing the number of wolves spotted in aerial surveys done last fall and this spring in a 2.5 million-acre conservation area in the preserve along the Canadian border.