
If everything
is perfect -- temperature in the 50s, a gentle misty rain and the
timing in sync with their internal clocks -- the salamanders will
cross en masse and head straight for the ponds. But if that enchanted
evening comes too early or too late in the season, the salamander
migration is drawn out over a period as long as two or three weeks.
An informal network of observers keeps watch throughout and relays
information about the year's migration to biology professor Dale
Madison, who has done extensive research on this particular
creature, Ambystoma maculatum.
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| Spotted
salamanders are about the size of a cigar. During the spring
migration, the females are a little larger because they're full
of eggs. |
When the spotted salamanders migrate en masse, "it's kind of exciting,"
said Madison. "You see a lot of very precious creatures in your
lamplight and feel good that you can help them on their journey."
Madison and the other observers facilitate the salamanders' safe
and successful crossing, either by guiding them to the ramps that
were built in 1978 just for them, or by gently picking them up and
setting them down on the pond side of the road.
"The curbed road acts as a dry moat," he explained. "They're not
very maneuverable creatures, so they fall down one side and bump
into the wall on the far side." Before the salamander ramps were
built, the amphibians became trapped in the roadway, where many
died of dehydration, were eaten by crows and other predators, or
were killed by traffic.
Once
Madison is assured the annual crossing is over, he makes a call
and gives the all-clear to Physical Facilities. Then, and only then,
the University reopens the road, which is closed in the winter.
This year, Madison gave the go-ahead to reopen the access road on
Monday, April 8.
Under-cover
insect control
One of many creatures that make up the ecological balance in the
Nature Preserve, this amphibian eats insects and worms and consequently
acts as a check on insect abundance. People rarely see spotted salamanders
at all, because they remain still and hidden under the leaf litter
throughout the summer, where they patiently wait for unsuspecting
meals to crawl by. Spotted salamanders are also called mole salamanders,
because in the winter they occupy tunnels thought of as occupied
by moles, Madison said.
The salamanders' return trip in the fall is much less synchronous
than their spring migration, Madison said. He knows, because he's
actually put mini-radio transmitters in them. "Some will make movements
out of the pond right away. Others wait to the end of the summer
to make the return trip," he said.
Another discovery Madison made in tracking salamanders' movements
is that the older spotted salamanders seem to abdicate the best
feeding and breeding grounds to younger generations, risking their
own lives in dangerous migrations to territories further away from
the pond.
Diminishing
numbers
The population of the spotted salamander is diminishing in New York
state, and that's one reason why they're of special concern, said
Madison. They can live 18 or more years, and they don't replace
themselves that readily. Although he doesn't have hard figures,
Madison believes that the population of spotted salamanders in the
Nature Preserve is lower now than it was 15 years ago, partly because
of the traffic and partly due to the beavers in the pond. "Beavers
tend to modify the habitat and make it less suitable for salamanders,"
said Madison.
"When people go out on wet evenings in early spring to jog or walk
on the access road, that's when they can do the most damage," Madison
said. So, tread cautiously on the roads in or near the woods on
misty spring evenings. It's a time that's crucial to the survival
of spotted salamanders, as it is to many creatures of the woods.
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Salamander
reproductive cycle
After spending a couple of hours on the access road watching
out for the spotted salamanders as they make their annual
trek from the woods to the pond, biology faculty, students
and friends often visit the pond to watch their courtship
in action.
"The males arrive first at the pond," said Madison. "Once
a female arrives in the water, nearby males zoom in and begin
nudging the female. Soon the males lay little tiny packets
of spermatophores on the bottom of the pond - they're like
little ice cream cones, a stalk and on top of that a little
bit of ice-cream sperm. Since it takes energy to make the
base of the ice cream cone, some males will cap off another
male's" -- in effect, creating a double scoop.
Next, if sufficiently excited, the female will draw her body
over the spermatophore packet, open the vent that contains
her eggs, and pluck off the ice cream that fertilizes them.
Then she'll go off to another part of the pond to lay the
fertilized eggs.
There are twice as many males as females in the pond, because
males migrate over to the pond every year, but it takes so
much energy for an egg-laden female to make the trip that
they only go every other year. "So there are always far more
spermatophores out there [than there are females to accept
them]," said Madison, adding that they look like "little clusters
of white dots on an otherwise black landscape of pond sediment
and rotten leaves."
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