|| Rohrbaugh, R. W., Reinking, D. L., Wolfe, D. H., Sherrod, S. K., Jenkins, M. A.
||In 1992 the George M. Sutton Avian Research Center initiated a five-year project to examine the nesting ecology of birds using tallgrass-prairie habitats in Oklahoma. The project was designed to help determine why grassland bird populations in the southern Great Plains are experiencing widespread and rapid declines. One of our objectives was to determine the effects of contemporary fire and grazing regimes on the nesting ecology of birds breeding in tallgrass prairie. From 1993-1995 we monitored nests on six 16.2 ha plots at the Nature Conservancy’s Tallgrass Prairie Reserve in Osage County, OK. Three of these plots were undisturbed (unburned and ungrazed) and three were disturbed (burned and/or grazed) during each year of the study. We monitored nesting success, clutch size, and fledgling rates at each of 313 Eastern Meadowlark, Grasshopper Sparrow, and Dickcissel nests on the six plots. We observed 42, 12, and 87 Eastern Meadowlark, Grasshopper Sparrow, and Dickcissel nests, respectively on undisturbed plots, and 60, 26, and 86 nests, respectively on disturbed plots. On undisturbed plots, the average Mayfield probabilities of nesting success for the incubation and brood rearing periods combined were 0.17, 0.17, and 0.19 for Eastern Meadowlarks, Grasshopper Sparrows, and Dickcissel, respectively; the average probabilities of success on disturbed plots were 0.07, 0.07, and 0.06, respectively. Clutch sizes and fledgling rates from successful nests were not statistically different between plot types. These results suggest that physiologically the reproductive performance of these species was not affected by burning and grazing; however, rates of nesting success for Eastern Meadowlarks and Dickcissels may be negatively affected by these activities. Through cooperative efforts with private landowners, we are currently developing management recommendations to mitigate the effects of burning and grazing on these species.