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Survival and Covey Density of Northern Bobwhites in Relation to Habitat Characteristics and Usable Space in Ohio

Knapik, Randall T

Abstract Details

2015, Master of Science, Ohio State University, Environment and Natural Resources.
Northern bobwhites (Colinus virginianus; hereafter, bobwhites) are gallinaceous gamebirds that were once ubiquitous across the eastern United States, but have declined throughout the 20th century. This research was conducted to evaluate the impact of woodlot edge-feathering and land use change on density and survival of bobwhites in Midwestern agricultural landscapes. I examined covey density, survival, and habitat use on 4 private-land study sites in southwestern Ohio to further understanding of winter ecology of bobwhites in relation to habitat characteristics and targeted woodlot edge management. Non-breeding season survival rate was at levels capable of stabilizing the population during the moderate winter of 2012 – 2013 (Ŝ = 0.393, 95 % CI = 0.215 - 0.596), but was well below the stabilizing rate during the severe winter of 2013 – 2014 (Ŝ = 0.075, 95 % CI = 0.037 - 0.145). I did not find a relationship between macro- and microhabitat characteristics and weekly survival outcomes during weeks with snow cover, although bobwhites restricted habitat use to areas of high woody stem density with increasing snow depths. This and persistently low survival rates in severe winters suggest that habitat conditions are homogenously poor and are not capable of stabilizing bobwhite populations, even at currently low densities. I examined the predicted probability of use and usable space by examining the proximity of focal habitat types. Loss of early-successional habitat features on the Fee, Thurner, and Wildcat study sites reduced their predicted probability of use and resulted in a net decline in usable space. Targeted successional management of woodlot edges (i.e. edge-feathering) on the Peach Orchard study site increased the predicted probability of use and the proportion of usable space. A reduction in the extent and mean predicted probability of use for herbaceous habitats on Fee indicate that loss of herbaceous habitat resulted in a coarser-grained landscape with less usable herbaceous habitat. Conversely, extent of early-successional herbaceous habitat was reduced on the Wildcat study site, but mean predicted probability of use for the habitat type increased suggesting that sufficient herbaceous cover remained for use during the non-breeding season. Covey densities and usable space increased or decreased concurrently on all study sites; however, changes in covey density and usable space were not proportional. Mean covey density declined between 2009-11 and 2012-14 on Fee (2009-11, 0.59 coveys/ km²; 2012-14, 0.22 coveys/ km²) and Wildcat (2009-11, 1.47 coveys/ km²; 2012-14, 1.37 coveys/ km²), but increased on Peach Orchard (2009-11, 0.45 coveys/ km²; 2012-14, 0.88 coveys/ km²) and Thurner (2009-11, 0.73 coveys/ km²; 2012-14, 0.84 coveys/ km²). Ecological density was calculated as the number of coveys per ha of usable space. Mean ecological density in 2011 and 2014 was 0.031 coveys/ha of usable space (range = 0.017 – 0.044). Management efforts must be prioritized in regions currently occupied by bobwhites and should seek to increase the proportional amount of usable space. Successional management of woodlot edges through edge-feathering and establishment of herbaceous field border programs should be implemented in agricultural landscapes of the Midwest to increase usable space and provide protective cover capable of withstanding severe winters.
Robert Gates (Advisor)
Steven Matthews (Committee Member)
Stanley Gehrt (Committee Member)
125 p.

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Citations

  • Knapik, R. T. (2015). Survival and Covey Density of Northern Bobwhites in Relation to Habitat Characteristics and Usable Space in Ohio [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1430738814

    APA Style (7th edition)

  • Knapik, Randall. Survival and Covey Density of Northern Bobwhites in Relation to Habitat Characteristics and Usable Space in Ohio. 2015. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1430738814.

    MLA Style (8th edition)

  • Knapik, Randall. "Survival and Covey Density of Northern Bobwhites in Relation to Habitat Characteristics and Usable Space in Ohio." Master's thesis, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1430738814

    Chicago Manual of Style (17th edition)