Adaptation of Salt Marsh Mammals to High Tides

Abstract

Observations on the activities of mammals during tidal floods at San Pablo salt marsh, Richmond, Contra Costa County, California, were made in 1951, 1952 and 1955. Most evidence on behavior was gathered at the time of diurnal high tides in December; additional observations were made in late spring in the breeding season. At high tide the marsh is covered by 1 to 4 feet of water, depending on the height of the tide and position on the marsh. At these levels usually only 4 to 15 inches of vegetation is left exposed; most of this is Grindelia cuneifolia, a woody perennial growing as a dominant along elevated banks of tidal sloughs. Comparatively little Salicornia ambigua, dominant on medium to high ground, or Spartina foliosa, a cordgrass dominant on low ground, is left uncovered. Since Grindelia grows along tidal sloughs, which twist and bend on themselves, the exposed...