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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

The Effects of Suburbanization on Nest Ectoparasites and Nest Defense Behavior in the Wood Thrush

Dalton, Evan N 07 November 2014 (has links)
The Wood Thrush (Hylocichla mustelina) is declining throughout its range, yet is capable of persisting in both contiguous forests and small forest patches surrounded by human suburban development. Thus, it is an ideal species for gaining insight into the effects of suburbanization on migrant songbirds. I investigated two aspects of Wood Thrush nesting ecology: nest ectoparasites and nest defense behavior in order to determine if suburbanization influences either aspect. Nests from suburban forests had fewer haematophagous mites, though the abundance of haematophagous blowfly larvae did not differ between suburban and contiguous forests. There was no relationship between the abundance of mites and nest site characteristics, though blowfly abundance may be related to nesting substrate species. Parasites had little effect on nestling condition. In regard to nest defense, suburban Wood Thrushes had shorter flight initiation distances and mounted more active defenses during initial nest visits than birds nesting in contiguous forests, suggesting a previously-established sensitization response to human disturbances in suburban birds. I found no consistent shifts in aggression over subsequent nest visits in either habitat type, suggesting that throughout the breeding season, Wood Thrushes neither habituate nor sensitize further to repeated human disturbances. My results suggest that Wood Thrushes nesting in suburban forest patches are subject to fewer nest ectoparasites and defend their nests more aggressively than conspecifics nesting in contiguous forests. These results draw attention to the fact that although Wood Thrushes persist in both rural and suburban habitats, their nesting ecology may be different between these habitat types.
12

Factors Affecting Habitat Quality for Wintering Wood Thrushes in a Coffee Growing Region in Honduras

Bailey, Brett A 04 November 2016 (has links)
Amongst the diversity of taxa that occur in the Neotropics, 200 migratory bird species that breed in temperate North America can be found. Many of these populations have seen significant declines since the 1960s. The Wood Thrush, Hylocichla mustelina, is one such species. Shade coffee and other agroforestry practices show potential for benefiting migratory species, but the quality of coffee habitat and optimal habitat characteristics for Wood Thrushes remain unknown. I surveyed a spatially complex, agricultural landscape in Honduras outside the recognized winter range of the Wood Thrush and radio-tagged 46 individuals within rustic coffee farms during the winters of 2012 and 2013. I used telemetry data to calculate metrics of habitat quality based on survival and persistence while also collecting detailed vegetation measurements across the landscape and within each home-range. Mixed-effects models were used to explore the relationship of survival, transience, movement, and home-range size to habitat class and microhabitat variables. Estimates for all four habitat quality metrics fell within the range of previous studies and were significantly related to habitat attributes. Structure, edge habitat, and shade coffee played a key role determining habitat quality. The variables associated with higher habitat quality in this study suggest that rustic coffee farms have potential to support wintering wood thrush populations. However, estimates of survival may be overly optimistic in the presence of transients, transforming highly fragmented landscapes into winter sinks. This study highlights several gaps in current scientific knowledge about some of the most essential questions of Wood Thrush winter ecology.

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