From
washingtonpost.com
What
a perfect time to be a frog. What were dry pools last year
are brimming with water now, and the evenings are warm enough
to hop forth in search of a mate. April and May are the
peak of mating season, when frogs are easiest to see and
hear because they are noisy and not always cautious.
In
the Washington area, the first amphibians to mate, wood
frogs, headed out from the forests to their breeding ponds
in mid-March. In milder years, they get going in February.
The
male of each species has a distinctive call. Right now,
you can hear the loud chirps of spring peepers, the buzzy
snore of pickerel frogs and the trills of American toads.
Later comes the twang of green frogs and the grunt of bullfrogs
-- sounds that can go on through the summer.
The
best time to see and hear frogs and toads is at night, starting
at dusk. They tend to sit on the edges of the water where
they mate, sometimes on reeds or grasses. Though closely
related, frogs and toads have different characteristics
-- toads typically have warty skin, for example, while frogs
have smooth or slimy skin.
John
Callow, a naturalist at Riverbend Park in Fairfax County,
advises standing at a distance from a pond at first, watching
through binoculars. Frogs often will scatter and go silent
if you get too close, but sometimes they will start up again
in a minute or so.
Sue
Muller, a Howard County frog expert, advises wearing "quiet
clothing" and being patient. Muller, who coordinates
volunteers for the national Frog Watch program at 35 sites
in Howard County, suggests not going frog-watching when
there is a full moon or a windy night, which inhibits the
amphibians. Federal scientist Robin E. Jung says that with
tiny spring peepers, "You have to triangulate to find
out where they are."
Some
frogs are active in daylight. A volunteer frog-watcher at
Riverbend saw 20 pairs of American toads "calling"
in midday a week ago. And spring peepers -- tree frogs that
chirp so loudly you can hear groups of them from inside
a car with the radio on -- do much of their talking during
the day.
After
they mate, females lay eggs in globs or strings, sometimes
thousands at a time. One female American toad can lay at
least 12,000 eggs, many of which will be eaten by birds,
fish or other predators.
The
eggs hatch into tadpoles. In two or three months, they turn
into froglets, then frogs. Depending on species, they can
live for two to 40 years, hibernating in mud through the
winter.
The
snowy winter and recent rains revitalized many "vernal
pools," the temporary wet areas that are the only breeding
ground for some types of frog and salamander. Last year,
amid the drought, some of the pools never held water.
This
year, scientists who monitor amphibian populations in Rock
Creek Park have found masses of salamander eggs in pools
that were dry last spring.
Amphibians
are closely watched indicators of environmental health because
they breathe through their skin, making them sensitive to
pollution, and because they live in both wet and dry habitats.
Scientists in some other parts of the country have made
alarming discoveries of frogs with missing limbs and strange
malformations, but Jung's group has found a low rate of
deformities in this region.
Still,
there are streams in Rock Creek Park with no salamanders,
probably because the waters are flooded with runoff from
road pollution during rainstorms, said Jung, who works for
the U.S. Geological Survey's Northeast Amphibian Research
and Monitoring Initiative. On the other hand, Rock Creek
is home to the northern red salamander and northern dusky
salamander, both of which are sensitive to contamination,
and Jung calls their current presence "a promising
sign."
For
more information about amphibians, including photos and
sounds, go to the Virginia Herpetological Society Web site
(fwie.fw.vt.edu/VHS/), or the Frog Watch site (www.frogwatch.org).
--
D'Vera Cohn
