Biology Reference
In-Depth Information
fields and urban landscapes. Indeed, birds associated with water seemed
to be suffering most from the onslaught of development all around the
bay and in the Central Valley. Bay waterfowl populations dropped to a
record low of 89,863 birds in 1995 (far below pre-1900s highs in the range
of 300,000).
Concerned about waning wildlife and fisheries nationwide, the federal
government passed legislation to preserve endangered species in 1966.
California followed with its own version in 1970. Clapper Rails, terns, and
trout were among the first bay species listed as at risk in California. Since
then, state and federal laws have continued to protect species from extinc-
tion in tandem. Between 1970 and 2010, the number of listed plant and
animal species found within or around California's coast grew from 32 to
177 (see also p. 183, “Mini Guide: Species in Peril”). Wetlands sustain 23
of the 32 species of wildlife declining in the estuary basin.
Around the bay, the fight to save the Salt Marsh Harvest Mouse and its
neighbor the California Clapper Rail has eclipsed all others. Three hun-
dred years ago, these animals lived in tidal marshes that stretched broad
and unbroken all around the bay. Uniquely adapted to this salty environ-
ment, the mouse evolved to become an agile swimmer and to eat the seeds
and shoots of halophytes. Whenever possible, it stayed dry by clambering
from stem to stem within its knee-high forest and weaving grass nests
within pickleweed boughs. Only the highest tides and lush summer
grasses could draw it into adjacent meadows.
The rail, meanwhile, stalked through the marsh in search of worms and
clams, mussels and snails, spiders and the mouse. It disappeared easily
into the thickets of cordgrass and pickleweed. At dawn and dusk, its clat-
tering call mixed with the cries of gulls and shorebirds.
Today, the daily activities of these two species may be the same, but
their environment is quite different. A jumbled matrix of salt ponds, dikes,
condos, roads, and riprap now surround and divide the remaining
marshes. Once-wide stretches of pickleweed and gum plant are now nar-
row strips along the steep sides of levees. Avenues of escape, dispersal, and
cover for both species during high tides are scarce. In some areas, treated
sewage discharge has freshened this once-salty world and shifted its vege-
tation mix. The mouse cannot use these freshwater plants as habitat.
The mouse can still be found in the marshes around Mare Island and
the sloughs east of Palo Alto and Mountain View, though sightings are
unlikely at best. The rail has hardly fared better. Between 1971and 2008,
their estuary populations dropped from as many as 6,000 to as low as 500
birds. The decline stems from a combination of habitat loss and intensified
predation. The rail can still be seen and heard every day off the wooden
boardwalk at Martin Luther King, Jr. Shoreline, though it also lives in
other bay marshes.
Search WWH ::




Custom Search