TWEL Randall Knapik Thesis

Survival and covey density of Northern Bobwhites in relation to habitat characteristics and usable space in Ohio

Randall T. Knapik, MS
Advisor: Robert J. Gates


Northern bobwhites (Colinus virginianus) were once ubiquitous across the eastern United States. Simplification of landscapes, expanse of row crop cultivation, and maturation of forested lands are widely accepted as the ultimate factors influencing the decline in the United States.
I examined survival, covey density, and habitat use in southwestern Ohio to quantify effects of landscape simplification in Midwestern landscapes. Non-breeding survival rate was at levels capable of stabilizing populations during the moderate winter of 2012 - 2013, but was well below during the severe winter of 2013 – 2014. I did not find a relationship between habitat characteristics and weekly survival during weeks with snow cover although bobwhites restricted habitat use to areas of high woody stem density with increasing snow cover. This and persistently low survival rates suggest that habitat conditions are not capable of stabilizing bobwhite populations during severe winters.
I examined landscape suitability through an analysis of inter-patch distance between focal habitat types. Covey densities and usable space increased or decreased simultaneously on all study sites; however, changes in covey density and usable space were not proportional. Loss of important habitat features on the Fee, Thurner, and Wildcat study sites resulted in a decline in usable space. Management of woodlot edges on the Peach Orchard study site resulted in an increase in usable space. Management efforts should aim to increase usable space through successional management of woodlots and establishment of herbaceous field borders.