Breeding Season Demography and Movements of Eastern Towhees at the Savannah River Site, South Carolina

摘要

The Eastern Towhee (Pipilo erythrophthalmus) has undergone population declines across much of its range, especially in New England. Despite being a widespread and, at one time, a common species, relatively little is known about its natural history, ecology, or demographics. We conducted baseline research on Eastern Towhees at the Savannah River Site, South Carolina, in 1995 and 1996 to estimate breeding season survival rates, nest success rates, breeding densities, and daily movements. We also were interested in whether towhees had differences in survival and movement rates between young and mature managed pine stands. We found that survival rates during the breeding season of radio-marked towhees did not vary by sex or stand type. Daily nest success rates were very low [0.62 ± 0.088 (SE)] as a result of high predation levels. Abundance estimates adjusted for sampling effort differed between years. In 1995, the abundance estimate was significantly lower in mature stands (7.1 ±0.47) than in young stands (9.6 ± 0.60) while in 1996, there was no different between mature stands (26.2 ± 5.67) and young stands (16.5 ± 3.39). Average daily movements by radiomarked towhees did not vary by sex or stand type. Movements among adjacent stands were common, and sometimes great distances.