Resource availability, breeding site selection, and reproductive success of red-winged blackbirds |
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Authors: | Andrew M Turner John P McCarty |
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Institution: | (1) Kellogg Biological Station and Department of Zoology, Michigan State University, Hickory Corners, MI 49060, USA, US;(2) Section of Ecology and Systematics, Cornell University, Ithaca, NY 14853, |
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Abstract: | Red-winged blackbirds are polygynous and show strong breeding site preferences, but it is unclear which environmental factors
regulate their reproductive success and are ultimately responsible for shaping their patterns of habitat selection and their
mating system. We evaluated the effect of variation in insect emergence rates on the reproductive success of male and female
redwings nesting on replicate ponds. The number of male and female redwings that settled on a pond varied two- to three-fold
among ponds, but was not related to insect emergence rates. Insect emergence rates had a positive effect on the number of
nestlings successfully fledged by females, the number of nestlings fledged from male territories, and on the mass of nestlings
at fledging. Typha stem density also varied widely among ponds, and was positively related to male and female settling density and mass of nestlings
at fledging, but not to the number of nestlings fledged by females or males. We conclude that alternative breeding sites differ
in their ability to support redwing reproduction, and that the availability of emerging odonates is an important environmental
factor influencing the reproductive success of both male and female red-winged blackbirds.
Received: 31 March 1997 / Accepted: 3 July 1997 |
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Keywords: | Aquatic insects Habitat selection Harem size Marsh Polygyny |
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