Date of Award

2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

City & Regional Planning

First Advisor

Thomas L. Daniels

Abstract

Throughout their range, North American grassland birds as a group have shown steeper and more widespread population declines than any other avian guild. Grassland bird decline corresponds to habitat loss, landscape fragmentation, agricultural intensification, and changes in land management. In areas where farmland is being converted, the presence or absence of grassland birds can be used to assess the availability of habitat across the landscape. Chester County in southeastern Pennsylvania has historically had an agricultural economic base, but since the 1980s, steady population growth and economic diversification have reduced the amount of available agricultural land in the county. In the last decade, efforts have been underway to slow land conversion and conserve working landscapes. Because Chester County has maintained its working landscapes despite development pressures, the county provides an opportunity to examine the effects of land use change and agricultural preservation on grassland bird occurrence. This dissertation uses fixed-radius point counts of six focal bird species on agricultural land in Chester County to evaluate the influence of landscape spatial patterns and land use planning outcomes on grassland bird habitat occupancy. Separate habitat models are generated for the focal guild and individual species to predict habitat occupancy within a 750 square kilometer area in Chester County’s agricultural belt. A landscape diagnosis of spatial patterns quantified by landscape metrics computed for discrete landcover types is developed to assess current landscape spatial patterns and proposed land use initiatives in the county as they relate to grassland bird conservation. The model outcomes and the landscape analysis indicate the grass-cropland network within the study area could provide suitable habitat for grassland birds. The study area has a relatively high level of spatial integrity for a county that has undergone rapid development and a core mixed agricultural area remains. These factors have important implications for the persistence of agricultural land uses and habitat availability for grassland birds.

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