Salt Marsh Harvest Mouse (Reithrodontomys raviventris; SMHM) , an endangered species endemic to the San Francisco Bay, coexists and competes with native and invasive rodents for resources. While intensive studies in recent years have revealed more about populations and habitat use among these species, little is known of the impacts of these competitive dynamics on daily ecological functions. Recent studies have shown SMHM to have a flexible diet though their foraging behaviors are not well understood, and even less is known about the diet and foraging of sympatric rodents. Opportunistic video and camera trap data collected during a long term study at a marsh in Marin County revealed communal foraging (up to three individuals) both by SMHM and separately House Mouse. Trapping data from this and other studies has shown SMHM to be less aggressive and more likely to behave communally during colder nonbreeding periods. While House Mice also seem to behave less aggressively and forage communally, the camera trap data indicates that their presence may preclude local foraging by SMHM. These observations support the importance and impact of competition in shaping SMHM habitat use. Further studies of foraging behavior across the small mammal community across the estuary may be warranted.