Northern Prairie Wildlife Research Center
ALAN B. SARGEANT, RAYMOND J. GREENWOOD,
MARSHA A. SOVADA, AND TERRY L. SHAFFER
U.S. Fish and Wildlife Service, Northern Prairie Wildlife Research
Route 1, Box 96C, Jamestown ND 58401
Survey methods used were systematic searches for presence or absence of carnivore tracks on quarter-sections (0.65 km²), daily records of number of different places (0.04 ha) where individual predator species were sighted, systematic searches for tree nests of large raptors and American crows (Corvus branchyrhynchos), and livetrapping of striped skunks (Mephitis mephitis) and Franklin's ground squirrels (Spermophilus franklinii). More than one method was used to assess abundance of some species.
Nesting ducks on all study areas were at risk to numerous predator species. Excluding large gulls, for which no indices were obtained, the number of predator species found on each area ranged from 8 to 14 ( = 12. 1); the number rated common or numerous on each area ranged from 4 to 9 (=6.2 [excludes raptors on some areas]). The striped skunk and great homed owl (Bubo virginianus) occurred throughout the Region and varied least in abundance. Most other species had uneven distribution or abundance. The Franklin's ground squirrel and red-tailed hawk (Buteo jamaicensis) were most associated with the aspen parkland portion of the region; badger (Taxidea taxus), Swainson's hawk (Buteo swainsoni), and ferruginous hawk (B. regalis) were associated most with prairie. The coyote (Canis latrans), black-billed magpie (Pica pica), and American crow were numerous most in Canada, whereas the red fox (Vulpes vulpes), raccoon (Procyon lotor), mink (Mustela vison), and ferruginous hawk were most numerous in the United States.
The greatest effect of predation on duck production in the Prairie Pothole Region is believed to be from destruction of clutches. The number of egg-eating predator species rated common or numerous on individual study areas ranged from 3 to 7 (=4.6). There was no major difference in average number of egg-eating species rated common or numerous on study areas by province and states, but there was a gradual replacement of mammals by birds from southeast to northwest across the Region.