Factors Influencing Gray Catbird and Wood Thrush Nest Survival
Date
2021-05
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University of Delaware
Abstract
Habitat fragmentation continues to be a pressing issue in conservation biology and wildlife management. Forest patches created by habitat fragmentation can have lower species richness, diversity, and demographic rates than contiguous forest habitat caused primarily by a suite of edge effects. Edge effects associated with forest fragments are especially prevalent in migratory forest breeding birds, but the degree of effects vary among species. Here, I focused on two deciduous forest migratory breeding species: Gray Catbird (Dumetella carolinensis) and Wood Thrush (Hylocichla mustelina). The goal of this project was to determine the factors that affect nest survival for Gray Catbirds and Wood Thrush breeding in forest fragments. I used existing nest data from 22 study sites, UD Ecology Woods, forest patches of Newark, DE and surrounding areas, from the years 2008-2016 for both species of interest, Gray Catbird (n=503) and Wood Thrush (n=401). I estimated the effects of distance to forest edge, nest height, and nest vegetation on daily nest survival for both species. I used MC estimate to generate estimates of daily nest survival probabilities given each variable of interest then assessed the models based on the corrected AICc values and model weights. I found that Gray Catbird survival was negatively related with distance to edge and declined over time although, these models did not differ from the null model. I found that Wood Thrush daily nest survival declined with increasing nest height. These results provide additional information for the factors that influence nest survival for these two species.
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Keywords
Habitat fragmentation, Gray catbird, Wood thrush, Nest survival