Predators and visitors to artificial nests, Spring/Summer 2002

Poor nesting success of songbirds in the Cosumnes River Preserve prompted this study to determine if nest predation was a factor.  Preliminary results from an analysis of predation on artificial nests has indicated that roof rats (Rattus rattus) are significant predators of songbird eggs.  We have now expanded this research to other riparian areas in California including Bobelaine Sanctuary (north of Sacramento on the Feather River) and Kern River Preserve, Southern California.  Although roof rats are well-known for their negative impacts on natural systems, there have been few attempts to document the impacts of these animals on natural systems in the continental USA.

We used Trailmaster camera units to identify predators and visitors of artificial nests placed in riparian areas.  Roof rats were the most common nest predator although some native species were also identified.  The following photos show some of our predators and visitors.

Many thanks to all my nest builders, and field assistants Kellie Collins, Sara Gillespie, and Jessie Quinn.

Nest Predators:
Eastern grey tree squirrel (introduced species)	Scrub jay
Ringtail, Bobelaine Sanctuary 2002	Skunk, Kern River Preserve 2002
Western grey tree squirrel, Bobelaine Sanctuary 2002	Roof rat (Rattus rattus), Cosumnes River Preserve 2002
Raccoon, Cosumnes River Preserve 2002	Male Bullock's Oriole, Kern River Preserve 2002
Visitors:
Woodrat, Kern River Preserve 2002	Cottontail rabbit, Bobelaine Sanctuary 2002