Geography Reference
In-Depth Information
It is not surprising that amphibians do best in cities that protect and
maintain the interface between water and land. This is a crucial transition
area that allows many frogs and salamanders to access the wetlands they re-
quire for breeding and the woodlands they seek for refuge and food. Protect-
ing wetlands is challenging in urban settings, because land values make it
proi table to convert wet areas to building sites by draining and i lling. But
those that remain are easy to identify and, if the political will is sui cient,
possible to retain. Knowing how much upland habitat is needed and how
close it must be to the wetland it nurtures is much more dii cult. Wood frogs
and spotted salamanders disappear from protected ponds in the eastern
United States as development i lls in around their breeding sites. The same
occurs in California, even where threatened tiger salamander breeding ponds
are conserved. From these studies and others that have radio tagged and
tracked salamanders and frogs as they come and go from breeding pools, we
know that the pond itself and the watershed up to about a half mile around it
af ect amphibians. The entire area need not be set aside, however. Even
small animals are able to cross substantial gaps—a distance of a football i eld
or more—between the pond and woods, if these areas include moist grass and
some shelter, such as small mammal burrows, leaf piles, downed branches,
or native shrubs.
Failing to provide connections between ponds and the uplands that are
reserved can be devastating to herps. Common toads throughout Europe
are slaughtered as they cross roadways that separate ponds from woods. In
France, a toad population was extinguished when every breeder was smashed
on a busy roadway that cut across a traditional migration path. Even more
robust and resilient reptiles become isolated in parks surrounded by roads.
Eastern box turtles in Rock Creek Park in Washington, D.C., for example,
are slowly drifting to extinction as new breeders rarely are able to cross the
busy roads that border the otherwise signii cant urban preserve. In contrast,
