DIFFERENTIAL OF COYOTES AND RED FOXES ON DUCK NEST SUCCESS

Low recruitment rates prevail among ducks in the Prairie Pothole Regio n of North America, primarily because of high nest depredation rates. The red fox (Vulpes vulpes) is a major predator of duck eggs, but fox abundance is depressed by coyotes (Canis latrans). We tested the hypot hesis that nest success of upland-nesting ducks is higher in areas wit h coyotes than in areas with red foxes. We conducted the study during 1990-92 in uplands of 36 areas managed for nesting ducks in North Dako ta and South Dakota. Overall nest success averaged 32% (95% CI = 25-40 ) on 17 study areas where coyotes were the principal canid and 17% (CI = 11-25) on 13 study areas where red foxes were the principal canid ( P = 0.01). Both canids were common on 6 other areas, where nest succes s averaged 25% (CI = 13-47). Habitat composition, predator communities with the exception of canids, and species composition of duck nests i n coyote and red fox areas were similar overall. Upon examining only n ests with greater than or equal to 6 eggs on the last visit prior to h atch or depredation, we determined nests with evidence characteristic of fox predation accounted for 4% of depredated nests in coyote areas and 27% in fox areas (P = 0.001). An expanding coyote population is co ntributing to higher overall nest success. Management of coyotes may b e an effective method for increasing duck nest success.