Habitat selection in overwintering White-throated Sparrow flocks in an Ohio experimental wetland ecosystem
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Date
2023-05
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The Ohio State University
Abstract
The White-throated Sparrow (Zonotrichia albicollis) is a native songbird that breeds in the boreal and mixed forest ecosystems of Canada and northern United States and overwinters primarily in the central and southern United States. During nonbreeding, White-throated Sparrows are highly gregarious, forming large foraging flocks. Populations of the species are in decline with its population decreasing over 30 percent the last 50 years with a particularly steep decline in the eastern U.S.A. (Hill, 2022). A lack of understanding on what habitat attributes are preferred by overwintering sparrows limits our ability to determine the cause of this species' decline. This study seeks to determine what fine-scale habitat variables in forested wetland ecosystems could improve winter flock survival. I test the hypothesis that White-throated Sparrows show preferences for habitat attributes that maximize protective cover and provide food resources. I predict that flocks will demonstrate avoidance of emergent marsh patches and select for early successional forest patches with fine-scale elements such as brushpiles, young eastern redcedar (Juniperus virginiana), and Amur honeysuckle (Lonicera maackii). In the winters of 2021-23 at the Wilma H. Schiermeier Olentangy River Wetland Research Park, White-throated Sparrow flock observations and vegetation surveys were conducted for a total of 86 paired flock and random points. Logistic regression models were used to predict the probability of sparrow use for 16 single habitat attributes and 15 a priori multivariate models. Results show positive selection for three habitat attributes in the top models: percentage eastern redcedar, percentage Amur honeysuckle cover, and proximity to brushpile suggest that White- throated Sparrows have a strong preference for cover habitat as well as nutritional foraging opportunities of eastern redcedar berries. I discuss management implications, including the implications of apparent selection for sites with invasive Amur honeysuckle.
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White-throated Sparrow, Zonotrichia albicollis, Olentangy Wetlands Research Park, habitat selection, wetland, vegetation survey