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Determinants of Breeding Distributions of Ducks

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Breeding Distributions of the Species

Green-Winged Teal.—This species had a distribution centered farther north than the other dabbling ducks. Only 4 of the strata with highest densities were in the southern prairie provinces (Fig. 7A).


gif --Green-winged Teal Distribution

Figure 7. (A) Average species density by stratum, 1955-81; (B) correlation between species density and local pond counts, 1955-81; and (C) correlation between species density and total pond counts, 1955-81.

Green-winged teal winter over a broad range in the southern United States and in Mexico. About 75% of wintering birds return to the major breeding grounds via the southern corridors. Most of the rest winter in the western states or western Mexico and move into Montana, Alberta, or northern breeding areas through a western portal (Bellrose 1980).

This species exhibited modest but consistent correlations between its density and local pond density except in the eastern and northern portions of the area in which ponds were surveyed (Fig. 7B; Table 3). Correlations tended to be high in the southwestern strata (especially eastern Montana and western South Dakota), although the species was uncommon there.

Green-winged teal populations displayed positive associations with total ponds throughout much of the southern prairie provinces, in northern Montana, and in eastern North Dakota (Fig. 7C). Negative correlations occurred in many northern strata.

Information on homing tendencies for green-winged teal is lacking (Table 4). We suggest that the majority of birds arriving in spring from the south settle in fairly good numbers in southern strata, if pond conditions there are favorable. Otherwise they proceed farther north. Many green-winged teal move to northern strata regardless of pond conditions to the south.


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