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Patuxent Science Meeting 2006 Poster Abstract

Spatial models of Northern Bobwhite populations for conservation

planning in the West Gulf coastal plain

Twedt DJ, Wilson RR, Keister AS

Since 1980, northern bobwhite (Colinus virginianus) suffered a 3.9% range-wide annual

population decline. Within the West Gulf Coastal Plain Bird Conservation Region in the south-

central United States, populations of this quail species have declined 6.8% annually. These

dramatic declines have sparked numerous recommendations for land use change and prompted

implementation of various conservation practices. However, to effectively reverse population

declines and restore northern bobwhite to their former populations, habitat conservation and

management efforts must target establishment and maintenance of sustainable populations. To

provide guidance for conservation and restoration of northern bobwhite in the West Gulf Coastal

Plain, we modeled their spatial distribution using landscape characteristics derived from 1992

National Land Cover Data (NLCD) and bird detections, from 1990 to 1994, along 10-stop

Breeding Bird Survey route segments. Four landscape metrics influenced northern bobwhite:

abundance was greater in areas with more grassland and areas where there was increased

aggregation of agricultural lands, but quail were less abundant in areas with increased density of

land cover edge and grassland edge. Using these landscape metrics, we projected the

abundance and spatial distribution of northern bobwhite across the entire West Gulf Coastal

Plain. Predicted populations closely approximated abundances estimated from a different cadre

of concurrently collected data. Our model predictions did not accurately reflect bobwhite

detections along species-specific call-count routes in Arkansas and Louisiana. Using the same

methods, we also projected northern bobwhite population distribution circa 1980 based on Land

Use Land Cover (LULC) data and bird survey data from 1978 to 1982. We compared our 1980

projections with our 1992 estimate of 1992 spatial abundance to identify areas of population

change. Additionally, we used our projection of the spatial distribution and abundance of

bobwhite to assess population stability. These projections provide needed guidance for

targeting habitat conservation and rehabilitation efforts for restoration of northern bobwhite in the

Friday, September 22, 2006



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