We studied incubation patterns and hatchability of Red-winged Blackbirds (Agelaius phoeniceus) nesting in two different wetland habitats—beaver ponds and sewage lagoons—in eastern Ontario during 1999–2001. We presumed that, if incubating Red-winged Blackbirds could acquire food more readily at sewage lagoons than at beaver ponds, they should respond by taking fewer and shorter foraging bouts, which would result in longer bouts of attentiveness, shorter incubation periods, and higher hatchability of eggs. Although differences were small, female foraging bouts were shorter and bouts of attentiveness were longer at sewage lagoons than they were at beaver ponds. Incubation constancies were subsequently greater, and, ultimately, incubation periods at sewage lagoons were shorter. Shorter incubation periods at sewage lagoons, however, did not result in increased hatchability. Our results suggest that, in habitats where incubating Red-winged Blackbirds can acquire food more readily, incubation periods may become shorter and incubation constancies may become higher.
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1 September 2005
VARIATION IN INCUBATION PATTERNS OF RED-WINGED BLACKBIRDS NESTING AT LAGOONS AND PONDS IN EASTERN ONTARIO
J. RYAN ZIMMERLING,
C. DAVISON ANKNEY
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