Northern Prairie Wildlife Research Center
Waterfowl Communities in the Northern Plains
Gadwall. -- The breeding distribution of the Gadwall is centered in the
Dakotas and the southern Prairie Provinces, and the Prairie Pothole Region of
North Dakota consists of strata in the highest quartile of average densities.
Populations declined somewhat during 1965-1989 at the continental scale, nd
the decline at Woodworth was more pronounced (Fig. 5).
Numbers of gadwalls in the Woodworth Study Area did not vary closely in
response to numbers of wetland sites, although Johnson and Grier (1988) calculated
r values of nearly 0.50 for that area in general. Gadwalls were more common
in years with cool April temperatures; the negative coefficient of May precipitation
in the best regression equation is difficult to explain.
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