Predator Control to Enhance Sandhill Crane Production at
Malheur National Wildlife Refuge
GARY L. IVEY, DAVID G. PAULLIN, AND
CARROLL D. LITTLEFIELD
Malheur National Wildlife Refuge, HC- 72, P.O. Box 245, Princeton,
OR
97721; U.S. Fish and Wildlife Service, 2800 Cottage Way, Room 1823,
Sacramento CA 95825; HCR-4, P.O. Box 212, Muleshoe, TX 79347
The population of greater sandhill cranes on Malheur National Wildlife Refuge decreased from 236 pairs to 186 pairs between 1973 and 1985 because of low recruitment, caused primarily by predation on eggs and young. Ravens, raccoons, and coyotes were identified as the major predators. After an extensive public involvement process and preparation of an environmental assessment, and because of this crane population's poor status, a decision was made to enhance crane production via predator control. In 1986, Animal Damage Control (APHIS) was contracted to conduct the control program on the Refuge, targeting these predators. The program is scheduled to continue through 1993, and is limited to units of the Refuge where cranes nest. The program was designed to be as selective and effective as possible, with control efforts focused on the cranes' breeding season.
Raven control was achieved primarily by using egg bait injected with DRC-1339, a very selective corvicide. Some ravens were also shot. Aerial gunning was the primary tool used for coyote control, followed by trapping and snaring, shooting, and denning. Raccoons were primarily trapped, although, a few were taken using hunting dogs and shooting. A total of 315 ravens, 1,078 coyotes, and 67 raccoons were removed from the area over the past four years.
Before the control Program (1973-85) crane nest success averaged 47% while during the control program nest success averaged 69%. Crane chick survival averaged 12% before the program, compared with 23% during the program. Crane production averaged 10.9 chicks per 100 pairs before the program, compared with 20.6 chicks per 100 pairs during the program. Also, waterfowl production was enhanced by the control efforts.
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