Master's Theses

Date of Award

Fall 2006

Degree Name

Master of Science (MS)

Department

Biology

Advisor

Elmer Finck

Abstract

The central grasslands of North America are a current focus for biological research because of the loss of native prairie across the continent. The loss of habitat due to farming, ranching, and urban development has adversely impacted a number of native grassland species including ground-nesting birds. Therefore, managers and landowners are interested in range management practices that might increase habitat for ground-nesting birds. Cattle (Bos taurus) grazing commonly is used by ranchers to manage, secondarily, for wildlife. However, previous research on two types of grazing systems, continuous grazing (CG) and rotational grazing (RG), has shown mixed results on the effects on ground-nesting birds. Some studies indicate positive grazing effects by reducing ground titter for brooding and foraging habitat. Other studies indicate negative grazing effects by increasing nest disturbance during the peak of the bird breeding season. The objective of my research was to compare the effects of CG and RG on ground-nesting birds in the Red Hills of south-central Kansas. Data were collected on 235 nests during the summers of 2004 and 2005. Nesting species included: wild turkey (Meleagris gallopavo), northern bobwhite (Colinus virginianus), mourning dove (Zenaida macroura), common nighthawk (Chordeiles minor), lark sparrow (Chondestes grammacus), grasshopper sparrow (Ammodramus savannarum), dickcissel (Spiza americana), eastern meadowlark (Sturnella magna), and western meadowlark (S. neglecta). My results indicated no significant difference between CG and RG treatments for avian abundance, avian richness, nest density, reproductive success, and vegetation characteristics at nest sites. However, brood parasitism by the brown-headed cowbird (Molothrus ater) was significantly higher on CG sites in both years. I found vegetation characteristics at paired random sites were significantly different between grazing treatments. I also found vegetation characteristics were significantly different between nest sites and paired random sites; birds selected specific vegetation characteristics at nest sites significantly more when compared to paired random sites. Overall, RG did not appear to have a more negative effect on ground-nesting birds in my study. However, my unequal number of sample sites (CG = 4, RG = 8), similar grazing densities, and variable environmental factors (e.g., soil type and precipitation) might have reduced my ability to detect significant differences between the two grazing treatments. A longer term study conducted at a larger extent of scale (more study sites across the counties of interest) on the effects of CG and RG on ground-nesting birds might produce different results.

Rights

Copyright 2006 Amy D. Zavala

Comments

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