![]() ![]() Wetland / Marsh / Facultative - frequent use Stream/River / Stream/River / Facultative - occasional use Riparian / Riparian Forest / Facultative - frequent use Lakes / Pond/Open Water / Facultative - frequent use Lakes / Lake / Facultative - frequent use Migrants may disperse east or west or northward prior to southward fall migration (Dugger and Fredrickson 1992).Īgriculture / Cultivated Field / Facultative - occasional useĪgriculture / Pasture/Old Field / Facultative - occasional useįorest / Conifer Forest - Mesic (average) / Facultative - occasional useįorest / Conifer Forest - Moist/wet / Facultative - occasional useįorest / Deciduous/Broadleaf Forest / Facultative - frequent useįorest / Mixed Forest (deciduous/coniferous mix) / Facultative - frequent use In the southeastern U.S., migrates farther south in years when spring-summer precipitation is below average and habitat suitability presumably is negatively affected (Hepp and Hines 1991). Migrants depart south by mid-March, arrive in northern breeding areas by mid-April (Palmer 1976). Southerly fall migration occurs mainly in October-November. Northern breeding populations migrate south for winter. In the southernmost breeding range, populations are essentially nonmigratory. Home ranges of breeding males in Minnesota averaged 202 ha and those of unpaired males, 526 ha (Gilmer 1971). Summer home ranges of of fledged broods were 0-12.8 kilometers along a river (Stewart 1958). Common predators of young include mink, raccoon, snapping turtle, bullfrog, largemouth bass, and other large predatory fishes. High annual mortality rate (commonly 50% in adults, higher in young of year). Most of the above information is from Dugger and Fredrickson 1992).ĭuring migration, sometime forms roosting flocks of 100 or more in winter, smaller groups of less than 30 are more common (Dugger and Fredrickson 1992). Yearlings may breed but often unsuccessfully or not at all. Young first fly at about 9 weeks, abandoned by parent at 1-2 months. Most juvenile mortality occurs during the first few weeks after hatching. Females with broods commonly move a kilometer or more from the nest site soon after hatching. Often two broods per year are raised in the south, occasionally in the north. Clutch size is 9-15 (usually 10-12), but more than one female may contribute eggs to a nest, resulting in nests with many more eggs (commonly up to 30 for successful nests in nest boxes). Nests are initiated as early as late January in the south, early March in the Midwest, and mid-March to early April in the north. Upon arrival in breeding areas, migratory females forage intensively and built up nutrient reserves prior to nesting. American Ornithologists' Union, Washington, D.C. ![]() BC Conservation Data Centre: Species SummaryĪmerican Ornithologists' Union (AOU).
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