The Milky Way, Andromeda and Cygnus X-1 – names that invoke a sense
of wonder for what might lie beyond our streaming blue sphere. The reality
of gravity dictates that we are not going there anytime soon, but I
say don’t dismay. You don’t need to visit distant galaxies to find alien
life forms. All you need to do is grab a pair of hip boots and a flashlight,
head out into the woods any warm March evening and follow the eerie calls
of woodland sprits. If you know where there’s a temporary pool of water
in your woods that eventual dries up by summer don’t dismiss them as
worthless woodland bathtubs.
Chances are that what you’re looking at is what wetland scientists term
a vernal pond. The word vernal simply means springtime and these specialized
habitats are anything but insignificant. Walking from the woods edge
into one of these vernal ponds is like slipping quietly through a transom
into another world. Like a flashback to the psychedelic sixties you’ll
see spots move (spotted salamanders), sticks with legs (caddisfly larvae)
and if you’re lucky enough, schools of dancing translucent bodies (fairy
shrimp) beneath the waters surface.
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| American Toad |
When the temperatures rise above 40ºF in March, I find myself gravitating
to some of my favorite vernal habitats to listen for the first Anuran
love cries to grace the air. Usually the bird-like trills of spring
peepers - a thumbnail sized tree frog and the duck-like croaks of wood
frogs will be the first to invite others of their kind to “do the swamp
thing”. Many frog species will use lake shores, ditches, marshes, bottomland
woods, and even tire ruts that fill with water to congregate. These
are generalists when it comes to the habitat types they choose to congregate
and breed. The strategy they deploy is to lay massive quantities of
eggs to equalize the effects of predators that stalk them in the hopes
that some will survive. Green frogs, spring peepers, American toads,
cricket frogs, leopard frogs and pickerel frogs (please visit the
Amphibians Tour Guide
page to see photos of these species) are common amphibian
denizens of our eastern forests adhering to the generalist policy. The
wood frog, on the other hand, is a specialist breeder that prefers to
mate in temporary water bodies. The common denominator these vernal
ponds impart is that they usually exist free of fish and eventually
dry-up. If you’re a wood frog this means that you must get to them early
- usually just after the snow melts and late winter rains fill them
to capacity, breed explosively, and quickly expedite your development. It takes a mere 90 days for a wood frog to go from egg to tadpole to
land roaming froglet.
You may find some of generalist frogs in vernal ponds but this is just
another wetland habitat to them. True vernal species like the wood frog
rely almost entirely on a vernal pond’s fleeting existence to fulfill
the breeding portion of their life history.
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| Wood Frog |
Throughout our treasured Garden State we have eight bizarrely unique
species whose sole survival hinge precariously with the existence of
these ponds. Vernal pond experts call these species obligate or indicator
species that help in classifying a pond as truly vernal. Two of the
eight species, the blue-spotted salamander and the startrekian looking tiger
salamander, are state endangered. The remaining five won’t be far behind
the endangered status if we continue to lose these vernal habitats.
Urban sprawl is the buzz word of the day and the fuel that fires the
disappearance of these tenuous woodland oases. The recipe for extinction
of local populations of obligate species is a simple one – remove the
pond – remove the breeding grounds - remove the species. The problem
is these habitats are often over looked, especially during summer and
fall when they appear to be merely faceless depressions in the landscape. This is why it’s essential for our kind to monitor and do everything
in our power to assure the safety of the pond.
The good news is the New Jersey Division of Fish ad Wildlife has been
actively monitoring and locating all the vernal ponds they can find. A database has been created solely for the purpose of knowing where
they exist. Environmental consultants, builders, local environmental
commissions and individuals that are planning to develop properties
can now use this database as a tool for their future protection.
The state actively seeks volunteers in this effort and all those interested
in vernal ponds or know where these ponds exist go to
http://www.dbcrssa.rutgers.edu/ims/vernal/
for further information.
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| Chorus Frog |
Becoming a volunteer for the state is endlessly rewarding for those
who choose to brave the elements. I can recall the first blue-spotted
salamander I found. It was a warm early spring evening preceding a heavy
thunderstorm where a chorus of peepers was so cacophonic I could barely
hear my own voice. In the deep recesses of the Great Swamp I was directed
by a biologist friend of mine to a small ephemeral pond where the elusive
blue spots were known to gather. After several empty passes with a dip
net I finally noticed some squirming movement amongst the algae and
detritus at the bottom of the mesh. When I gently lifted this silky
cerulean gem out of its binds, I felt as if I discovered another continent. This awe-inspired creature harbored bulging eyes with a chunky body
fissured with what herpetologists term coastal grooves and bespangled
with rich blue spots. I thought for a moment how lucky I was to be there
and feel the earth exhale.
The blue spotted salamander is a member of the mole salamander family
– Ambystomidae. With its other vernal pond obligate cousins, the eastern
tiger, Jefferson’s, marbled and spotted salamander, these species are
seldom seen outside of their breeding pools.
This is because to be a member of the mole salamander alliance is to
lead the life of a mole. Using small mammal burrows to forage for spiders,
earthworms, insects, and millipedes these salamanders rarely venture
above ground with the exception of the cold March dance.
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| Blue Spotted Salamanders tête-à-tête |
I would be remiss if I stopped my vernal ranting here without mentioning
one of the most mind-boggling creatures to inhabit these ponds. I alluded
to them earlier when I talked of dancing shrimp beneath the waters surface. These are the fairy shrimp related to but not closely associated with
the Red Lobster ones most of us peel and eat by the dozen. Tiny little
upside down swimming multi-legged spectacles, these crustaceans pull
off one of the coolest magic tricks in Mother Nature’s playbook. Intolerant
of pollution, siltation, salinity, and excessive temperatures, fairy
shrimp need the clean cool waters of vernal ponds to breed. Sometimes
you’ll find a pond where the water gets cloudy with thousands of these
frantic beauties. After coupling with their male counterparts, the females
start to bulge with eggs and as the season progresses they pass with
the evaporation of their home. The eggs left behind are nothing short
of amazing. Pinhead sized, desiccant resistant, and seemingly lifeless
discs, the eggs can pass through several years of drought only to hatch
when the right conditions return. The resting eggs have been shown to
survive drying, extreme heat, freezing and the digestive tracts of birds!
Vernal ponds play out every bit the fascinating life and death struggles
that make grander ecosystems so fascinating. The players in the pool
are too many for one article. Hopefully I’ve spiked your interest enough
to get out some balmy night this month to explore the other universe
that is a vernal pond.
If you are interested in learning more about vernal ponds, please see
Blaine's program on vernal ponds under
services..
