Northern Prairie Wildlife Research Center
GARY L. KRAPU, PAMELA J. PIETZ, AND CARMEN R. LUNA
U.S. Fish and Wildlife Service, Northern Prairie Wildlife Research
Route 1, Box 96C, Jamestown, ND 58401
Concerns raised by this information prompted us to more fully assess effects of fence design and time required by broods to exit the exclosures. We conducted an experiment with radio-tagged gadwall ducklings in two exclosures that had different numbers and sizes of exits available to hens. Results indicated that hens with broods left four times faster from the exclosure with larger, more numerous exits. During the 1990 field season, we tested another type of hen exit intermediate in size to those we had tried previously. The test also compared exits to which hens were directed by means of a lead and exits without leads. Preliminary results of this work will be addressed in the presentation.
Long delays at exclosure fences increase the potential for duckling mortality from several combined or independent factors: exhaustion, exposure, abandonment, and predation. Predation events we observed near exclosures emphasized the need to maintain high-quality escape cover both within an exclosure and in the corridors that broods are likely to use while enroute from the exclosure to water. To minimize the time broods are delayed by exclosure fences, we recommend that they be designed to allow hens with broods to exit the structures on the ground.