Graduate Thesis Or Dissertation
 

Comparative ecology of bobwhite and scaled quail in southern Texas

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/n009w507b

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  • For my research goals I addressed the theoretical importance of competition in habitat selection of 2 quails and examined the use of resources in peripheral and core areas. Methodological objectives were to determine cover and food selection of Texas bobwhite (Colinus virginianus texanus) and chestnut-bellied scaled quail (Callipepla squamata castanogastris) in southern Texas. The Welder Refuge was the core area for bobwhites. The Chaparrosa and Experiment Ranches were peripheral areas for both quails. The core population for scaled quail was located at the Killam Ranch. Available cover formed a gradient from Welder to Killam. The highest percentage of herbaceous material was on Welder, whereas the largest amount of bare ground and shrub cover was at Killam. Bobwhites and scaled quail used and preferred different cover types. Bobwhites selected dense herbaceous material, whereas scaled quail preferred sparse vegetation and a shrub overstory. Based on niche breadth estimates, both quails used a narrow range of cover types in their respective core areas and a broad range in the peripheral areas. The frequency of available food items also formed a gradient. Welder had the largest percent frequency of animal matter and of herbaceous seeds and green leaves. Killam had the highest frequency of seeds, leaves, and fleshy fruits from woody plants. Bobwhites preferred grass seeds and animal matter, whereas scaled quail selected the fruits and seeds of woody plants. Niche breadth estimates were relatively constant for each quail. Theoretically, when intraspecific competition is most intense a species selects a broad range of habitats, whereas sympatric species occupy a narrow range of resources due to interspecific competition. However, when I used niche breadth estimates to address my first goal, neither component of the habitat (cover or food) followed the anticipated pattern. Therefore, I believe competition is not the major selective force in habitat selection of quails. The generalization has been put forth that in the peripheral part of a range birds occupy their optimal habitat, whereas at the center of the range, optimal and suboptimal habitats are used. However, the core area contains an abundance of preferred habitat and a species is able to meet its life-history requirements within a narrow range of cover types. Peripheral areas supply only suboptimal habitat and in order to fulfill the species-specific needs a species must use a wide range of cover types.
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