NESTING AND FORAGING BEHAVIOR OF THE SALT MARSH HARVEST MOUSE IN A SOUTH BAY STRIP MARSH

Laura Coatney; Alluvion Biological Consulting; lcoatney@alluvionbc.com; Vanessa Hernandez, Rachel Stump, Sean MacDonald, Carla Angulo, Stephan Wilson, Rachel Tertes, Laureen Barthman-Thompson, Katie Smith

During a habitat enhancement effort at tidal strip marshes surrounding restored salt ponds in the South San Francisco Bay a high density of rodent nests were observed, many of which could be attributed to the salt marsh harvest mouse (SMHM; Reithrodontomys raviventris) an endangered San Francisco Estuary endemic. In addition to nests, ample evidence of rodent foraging was observed in many forms. Here we will describe several types of nests, including resting and piping, and provide photos and an analysis of placement and density. Nests were found in low, mid, and high marsh, and on levee tops, in a variety of vegetation types including, and most commonly, pickleweed, alkali heath, and marsh gumplant. Evidence of rodent foraging was also found throughout marsh zones and vegetation types, ranging from hulls of consumed seeds to apparently cached insect eggs. Often observed were what we describe here as “galleys,” locations or platforms where SMHM (or other marsh rodents) harvest, age, cache, and consume plant and insect matter. Photographs as well as instructions for locating and identifying galleys are presented here. These observations vastly expand our knowledge of SMHM nesting and foraging and will improve avoidance and minimization methods for future habitat enhancement efforts.

Poster Session  InPerson Presentation