Annual Survival of Winter Residents in an Urban Wetland
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Date
2021-05
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The Ohio State University
Abstract
Winter can have important demographic consequences for wintering resident avian species that reside in the temperate zone. Shortened days and inclement weather challenge survival, with urbanization and climate change only heightening these affects. Survival during the wintering period can even be the main limitation to a population's growth, a direct factor to population size. Thus, understanding the characteristics that determine which species may be more vulnerable to the effects of urbanization and climate change during winter is of high conservational value. To address these questions, I investigated apparent annual survival probabilities for three focal species that varied in life history characteristics within an urban wetland. Specifically, I studied one resident species (Carolina chickadee Poecile carolinensis), one partial migratory species (Song Sparrow Melospiza melodia), and one obligate migratory species (White-throated Sparrow Zonotrichia albicollis). I applied mark-recapture methods over a 5-year period to create capture histories and estimate apparent annual survival for both immature and adult birds. Apparent annual survival was consistent across years and ages in resident and partial migratory species, but varied by both year and age within the fully migratory birds. Additionally, White-throated and Song Sparrows averaged a higher apparent survival than the Carolina Chickadees. My results suggest that migratory species exhibit higher survival than resident birds, which may be a tradeoff with reproduction, based on known clutch sizes. I also conducted a preliminary examination of annual environmental trends with White-throated Sparrow survival. This suggested survival was lowest in harsher winters with lower average temperatures or higher amounts of snowfall. These results have potential implications for the conservation of winter residents in the temperate zone, but further work is required to establish environmental relationships.
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Keywords
overwintering period, migration, annual survival, avian, urban wetland