Distribution and Abundance of Predators That Affect Duck
Production: The Prairie Pothole Region
ALAN B. SARGEANT, RAYMOND J. GREENWOOD,
MARSHA A. SOVADA, AND TERRY L. SHAFFER
U.S. Fish and Wildlife Service, Northern Prairie Wildlife Research
Center,
Route 1, Box 96C, Jamestown ND 58401
During 1983-88, the relative abundance of 16 species of mammalian and avian predators believed to significantly affect duck production in the Prairie Pothole Region was determined for 33, 23-26 km² study areas scattered throughout the Region. Individual areas were studied for one to three years. Index values obtained for individual species were used to rate abundance of nearly all species on each study area as undetected, scarce, uncommon, common, or numerous.
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.
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