Video documentation of predators and nest defense at Bachman’s Sparrow nests

摘要

Bachman’s Sparrow (Peucaea aestivalis) is a species of conservation concern throughout its range and an effective indicator of healthy pine savanna ecosystems in the southeastern United States. Their secretive nesting behavior means that many aspects of their nesting ecology, including specific knowledge of the nest predator community and nest defense behaviors are insufficiently described. This information is an important first step in determining the link between management practices and reproductive success. We monitored 86 Bachman’s Sparrow nests, 65 with constant video surveillance, to describe the nest predator community, cause-specific nest mortality rate, and nest defense behavior. We identified 12 predator species from 37 predation events. Snakes were the dominant predator type, responsible for 51% of identified predation events, followed by mesomammals (19%), small mammals (16%), and others (14%). Nest defense behavior included ptiloerection and chasing but was rare (16% of predation events) and effective 67% of the time. Daily nest survival was 0.936 (CI: 0.894 – 0.967) and neither season, year, nor site explained a significant amount of variation in estimates of cause-specific daily nest mortality. Raccoons were not detected at Bachman’s Sparrow nests despite being one of the most common nest predators in other avian nest surveillance studies. Future studies should explore the link between prescribed fire, nest predation, and snake abundance or activity in southeastern pine savanna.