SSRP Abstract

Board 24: Caught in the Act: Investigating the Relationship Between Songbird Nest Microhabitats and Predation in a Desert Environment

Student Scientists: Josie Fornara ’23 and Lily Hambric ’24
Research Mentors: Laurel Anderson and Dustin Reichard (OWU Department of Biological Sciences)

Understanding what causes some bird’s nests to successfully produce young and others to get eaten by predators is essential for directing effective conservation efforts. With this in mind, we wanted to know whether the amount of foliage concealing a nest determines the types of predators that will attack it — for example, are foxes significantly more likely than snakes to attack a well-concealed nest? To tackle this question, we spent six weeks in New Mexico using trail cameras to monitor the nests of Black-throated Sparrows, a common desert songbird. So far, our camera images have revealed that a variety of predators prey on Black-throated Sparrow nests, though we have not yet identified any relationships between nest-site vegetation and specific nest predators.

Predation is by far the leading cause of nest failure in birds. Consequently, birds should benefit from choosing nest locations that reduce the risk of predation by limiting predators’ ability to detect nests (i.e. nest concealment hypothesis). To understand how nest concealment and other nest-site vegetation characteristics affect the likelihood of predation by specific predators, we monitored the nests of free-living Black-throated Sparrows (Amphispiza bilineata) at the Sevilleta National Wildlife Refuge in central New Mexico. Of the twenty-four nests that we observed, seven fledged successfully (29.2%), nine were predated (37.5%), and eight were still active at the conclusion of our study (33.3%). We used camera traps to monitor the activity at each nest and to identify the predators responsible for each nest failure. After a nest became inactive (i.e. fledged or failed), we removed the camera trap and measured the height and diameter of the nest shrub, the average number of branches offering lateral concealment of the nest, and the distance to the nearest shrub/agave in each of the four cardinal directions. We also used fifty-meter transects to survey shrub/agave diversity in the vicinity of the nest shrub. Preliminary results show that a Brown-headed Cowbird, a snake, and a fox were responsible for three of the predation events, but our analysis is ongoing. Thus far, our results do not demonstrate a clear relationship between nest-site vegetation characteristics and specific nest predators.