PARENT SESSION
Oral Session 2: Avian Ecology I: Habitat and Disturbance.
Presiding: D Miles and C Lepczyk
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room A 106.
Climatic variability and predator abundance mediate the interaction between an invasive shrub and nesting success in a woodland songbird.
Schmidt, Kenneth*,1, Nelis, Lis 2, Briggs, Nathan3, Ostfeld, Richard 4, 1 Texas Tech University, Lubbock, TX2 University of Chicago, Chicago, IL3 4 Williams College, Williamstwon, MA
ABSTRACT- Previous studies have suggested synergisms between the effects of invasive species and climate change. Veeries (Catharus fuscescens) frequently build nests in an exotic shrub, Japanese barberry (Berberis thunbergii), in southeastern New York. We monitored Veery nesting success over 6 years and supplemented these observations with experimental nest studies. Using experimental nests, we found that nests placed above the ground in either barberry or native plants survived significantly longer than ground nests, but predation did not differ between the two former sites. Similarly, Veery nests on the ground suffered higher predation rates than nests in either raised native substrates or barberry; however, despite a substantially lower daily mortality rate in barberry the difference was not significant. The lack of significance is apparently related to temporal variability in substrate or habitat preference by Veeries and strong temporal variation in the assemblage of the nest predators. Barberry offered relatively greater refuge from nest predators during outbreaks of rodent populations (r2 = 0.693, P = 0.02). Years with higher spring precipitation reduced the use of mesic drainages (where barberry is abundant) for nest sites and concomitantly fewer nests were placed in barberry (r = -0.897, P < 0.05). While the differences in nest predation rates were relatively small, we estimated that nesting in barberry versus on the ground can caused an approximately 10% increase in annual fecundity. Thus, strong differences in the density (e.g., time since invasion) of barberry and chronic changes in climate can have long-term impacts on songbird populations.
Key words: nest predation, invasive shrubs, Veery