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Mouse, cont.
The salt marshes of the 1850s had, and a few marshes today still have, three broad zones of vegetation bordering the grasslands that surrounded the Bay: cordgrass (Spartina foliosa) in the lowest, most tidally influenced zone; pickleweed (Salicornia virginica) in the middle; and an upper zone of various peripheral halophytes (or salt tolerant plants) that grow along the Bay’s upper edge. Historically, there were also small ponds located in the upper zone. Migratory waterfowl and shorebirds used those natural ponds, tidal channels and mudflats much like these birds use artificial salt ponds and adjacent channels and mudflats today. The marshes of the 1850s were much more extensive and contiguous than today’s, reaching into the grasslands on all sides of the Bay. Similarly, the branching tidal channels were more prevalent and complex. Today, many of the Bay’s marshes of may look like complete marshes to the general public but are probably not an acceptable marsh as seen by the salt marsh harvest mouse. Unacceptable marshes for mice have resulted primarily from changes to the vegetation zones. The South San Francisco Bay marshes |
in your hand and imagining a complicated,
active, furry, small mammal weighing that little. Since they are so small,
salt marsh harvest mice do not live long; a life time of nine months is an
exceptional one. The average female has one litter of three to four young,
although a few mice may have two litters during their short lives. Biased
as I am after many years of studying salt marsh harvest mice, I think they are beautiful - small, relatively
calm animals with big eyes and appealing faces. So, why are such innocuous
and charming animals on the endangered species list? The simplest answer is
that the salt marsh harvest mouse has slowly disappeared as humans have modified
what has long been considered that "worthless marshland along side the
Bay". Last updated:
May 27, 2008
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