Geography Reference
In-Depth Information
and snake-necked turtles, carpet pythons, and blue-tongued lizards in Aus-
tralia; sand lizards in Berlin; and the marsh frog throughout Europe, for
instance— become abundant.
In a few instances the collapse of urban reptile and amphibian popula-
tions is well documented. New York City supported i fteen species of snakes
and salamanders in the late 1800s, including poisonous copperheads and tim-
ber rattlesnakes. Today, only two snakes (neither poisonous) and three sala-
manders (all rare) survive. They share the city with i ve species of frogs, two
species of toads, and six species of turtles. The Italian wall lizard is a new ar-
rival i rmly established in the city, and occasional boas, cobras, and alligators
escape their cages and scare residents. A richer complement of snakes, sala-
manders, toads, frogs, and turtles lives just beyond Manhattan in the wilder
parks of Staten Island and Long Island. London's natterjack toads were lost
in the 1960s, and poisonous adders and common toads have been greatly
reduced. One-quarter of San Francisco's herps were extinguished from the
city between 1855 and 1963, and today, although sixteen native species can
be seen, only four—the rubber boa, coast garter snake, California slender
salamander, and arboreal salamander—are considered common. In just half
a century, from 1920 to 1973, all species of salamanders, i ve species of frogs,
and two species of snakes were extirpated from Hamilton, near Toronto,
Canada.
In the state of Maryland, scientists wade the streams every year to system-
atically search for amphibians and measure the chemistry and composition of
the watersheds that af ect them. By checking more than three thousand loca-
tions over a decade (1995-2004), they found an astonishing diversity of stream
and moist, riparian forest amphibians—forty-one species in all, about half
frogs and half salamanders. They also discovered that urban sprawl, and es-
pecially the pavement associated with it, was the biggest stressor to amphibi-
ans, lowering their diversity precipitously. Worldwide, urbanization af ects
