It is that time of year when we need to slow
down on our way to and from Tybee, if we are to
avoid hitting the female Diamondback Terrapin (Malaclemys
Terrapin). Laden with eggs, the females begin
their hunt for high ground to bury eggs.
Searching for suitable nesting sites they cross
the Tybee road and perish. We need to look at
alternatives to the annual slaughter of
Diamondback Terrapin on the Tybee road.
Wild life crossings. If we are to
preserve our population of terrapin on and
around Tybee Island we need to consider one
aspect of their survival that we can control,
traffic mortality. Construction to widen and
raise route 80 is slated to begin in 2008. High
priority funding has been given to the project.
The road shoulder will extend 27 feet from the
edge of the highway or white line. At the outer
edge there will be a two foot concrete drop off,
to serve as a wildlife barrier. The barrier will
not be seen from the road but will present
terrapin with a two foot concrete wall,
eliminating their access to the highway. This
will increase survival rates greatly, but
without wildlife crossings it may not go far
enough.
Fragmented landscape. As the highway
stands now it bisects four and a quarter miles
of salt marsh, creating two different
populations of Terrapin. The Federal Highway
Administration has become increasingly aware of
the negative effects roads can have on wildlife.
The Federal Highway Administration says, “If a
highway actually prevents one population from
mating with other populations of its species,
the isolated group could literally become
genetically inferior.” This agency goes on to
say, “When highways fragment landscapes, they
divide wildlife populations into smaller, more
isolated units. Smaller populations are less
stable and over time, face extinction from
predators or natural causes. They may also be
susceptible to inbreeding and genetic defects.”
Darryl Van Meter, Georgia Department of
Transportation’s project director for the new
Route 80 has cited hydrological imbalance as a
reason for not having wildlife crossings. In
other words, the movement of water created by
such openings could have a negative impact on
the marsh.
However, local naturalist Mallory Pearce
disagrees. He doesn’t see a problem with
removing portions of a manmade barrier in the
marsh. He points out, “You want to have a free
flow of the tides throughout all sections of the
marsh. Isolated sections could have their saline
balance disturbed and become too salty or
inversely, inundated with fresh water.”
Georgia coast boasts largest population.
Georgia has the most robust population of
diamondbacks, due to the vastness of our
protected salt marshes. Georgia has one third of
the total salt marsh found on the East Coast.
Diamondbacks range from Cape Cod to Corpus
Christie, Texas. This wide range has caused them
to adapt to very different conditions, creating
seven sub-species; the Carolina diamondback is
found here. They are the only turtles in the
world that live exclusively in brackish water
(somewhat salty).
Exotic appearance creates demand. Each
turtle has a distinct set of black squiggly tear
shaped markings that dapple its whitish skin on
its head, neck and legs. The name is derived
from the diamond-shaped, grooved concentric
rings on the scutes of their Plastron, or the
top half of their shell. Their unique markings
have made them popular with the pet trade, and
they are bred in captivity. There are entire web
sites dedicated to the husbandry of Diamondback
Terrapins, advertising adults for $150.00 or
more.
No longer a game species. Currently
Diamondbacks are not threatened as a species in
our state, but just last year the legislature
changed them from a game species to a non-game
species. This prevents any removal from the
wild. People often take turtles, being slow
moving and non-aggressive, to keep as pets. A
saltwater fishing permit no longer allows the
collection or harvest of Diamondback Terrapin .
Conservation efforts. Even though they
are not yet listed as threatened, their numbers
are dwindling. Due to loss of habitat, they
travel farther in search of nesting sites, which
often leads to traffic related, deaths. In
states like Maryland and New Jersey,
conservation programs aim to rescue injured
diamondbacks and retrieve eggs from recently
killed terrapin. The viable eggs are then
incubated and the hatchlings over wintered in
captivity, before being released into the wild.
Other hazards Diamondback Terrapin encounter are
crab traps. Terrapins enter traps in pursuit of
bait that is set for the blue crab. Although
they may stay underwater for hours at a time,
prolonged captivity in a crab trap leads to
drowning. Some crabbers have been experimenting
with turtle exclusion devices for traps. Instead
of a horizontal entrance, a vertical entrance is
used. Crabs will readily swim sideways to enter
these traps but turtles are reluctant enter
because they would have to leave their upright
position, which would cause them to tip over.
Turtle soup. The Diamondback Terrapin
were nearly decimated in the late 1800’s and the
early 1900’s when Diamondbacks were considered a
delicacy and there was a rage for gourmet food.
Terrapin actually comes from the French word
meaning turtle soup. Wine was a common
ingredient. Fortunately for the Diamondback the
stock market crash of 1929 and the advent of
prohibition (1920-1933) led to a marked decline
in the demand for their meat, hence the release
of large numbers of Diamondback Terrapin into
the wild. This sudden release of turtles,
collected from all up and down the coast, led to
a lot of interbreeding.
Large females dwarf males of the same species.
The casual observer may tend to think that all
Diamondback Terrapin s are about nine inches in
size since we only see the larger females
crossing the road on their hunt to find high
sandy ground during breeding season. Their male
partners at only half the size, remain in the
water. The species is sexually dimorphic; the
females when they reach maturity are twice the
size of adult males. Females also have a larger
head adding to their bulkier and stouter look.
Eggs in demand and at risk. In spring
they leave their aquatic existence and search
out a place to bury five to eighteen eggs six
inches deep in the sand. Even after she has
navigated her way to a nesting site, there are
still other dangers. Hungry feral hogs and
raccoons commonly eat eggs. Even humans
sometimes collect the eggs and sell them as
aphrodisiacs. The eggs hatch 60-120 days later,
depending on the temperature. Often the young
terrapin will remain hibernating in the nest
long after hatching and then emerge on a warm
sunny day in the middle of winter.
Hatchlings vulnerable. When they decide
to venture out of the nest they fall prey to
birds and in some cases alligators. Ghost crabs
that live on the beach will grab a hatchling,
poke its eyes, and haul it down into their
burrow to keep as a live food source. Studies
are not readily found on the survival rate of
Diamondback Terrapin but if you look to another
species, the Loggerhead Sea turtle, prospects
are grim. Out of ten Loggerhead nests, with
approximately 100 eggs per nest there will be
one Loggerhead to live to maturity.
Life in the salt marsh. Diamondbacks are
very well suited to life in our salt marshes. By
day they dine on fiddler crabs of which we have
approximately one million per acre in the salt
marsh. They also eat the periwinkle snails,
which live on our spartina grass, migrating up
and down the stalks according to the snail’s
internal tide clock. Diamondbacks eat shrimp,
fish, mussels, clams, worms and plant shoots.
They burrow under the mud to sleep, or if it
gets particularly cold. They have
disproportionately large powerful hind feet for
navigating in the strong tidal currents and
undertows. In some of our narrow creeks, the
tidal current can run as strong as 7-9 miles per
hour.
Positive steps are being taken. The
United States is catching up to Europe, tackling
the problems created for wildlife by our endless
roads and automobile dependent society. Congress
is considering including provisions in a new
six-year plan for transportation that would
require states to plan not only roads, but also
ways for wildlife to safely cross them. A new
bracnch of science called “Road Ecology” has
sprung up.
States and individuals are addressing the
problem on a local level too. The Wyoming
department of Transportation officials installed
a $400,000 wildlife underpass along Highway 30
(a stretch of roadway that lies along the Mule
Deer’s migratory path) as well as eight miles of
fencing to funnel the deer to a crossing point.
Between 1,500 and 2,000 deer move through the
structure annually.
Last year a group of Cornell students built a
toad passage under a road in the college to
prevent the decimation of local amphibian
populations during their mass migration to
spring breeding ponds. Migrating salamanders in
Amherst, Massachusetts, use similar tunnels to
reach breeding sites. Where man and animal meet
on their separate journeys has become and issue
throughout the country.
