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From
the Field:
Destination - Exuma Islands
Shedd Aquarium's 2003 Bahamian Expedition
May
22, 2003
Gaulin
Cay:
Reporting
from the field: Chuck Knapp, Conservation Biologist, Shedd Aquarium
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| Chuck
Knapp with an iguana. The iguana is being held by Stephanie
Coon, an expedition participant.
Credit: Shedd Aquarium
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For the
past two-days we have left the azure waters aside and have hit the
jagged limestone and verdant tangle of shrub in search of the endangered
Exuma Island iguana, Cyclura cychlura figginsi. Our study site is
Gaulin Cay where Shedd Aquarium participants have been helping monitor
the island iguanas since 1998. The Exuma Island iguana belongs to
a group (genus Cyclura) that are among the most endangered lizards
in the world. This not so envious distinction is caused by habitat
loss, subsistence hunting, illegal wildlife smuggling, and competition
with and predation by feral animals. The data we gather is therefore
extremely valuable considering the remoteness of the cays and the
difficulty in sustaining a long-term program in the central Exumas.
We dress
up for the occasion by leaving the swimsuits behind and donning
long pants, boots, hats, sunglasses, and copious amounts of sunscreen.
After the students learn the art of iguana capture and restraining
techniques, they splinter off in groups armed with long-handled
nets and pillowcases. Excited shouts punctuate the air as iguanas
are sighted and the students move into a circular position around
the animal. With adrenaline surging, students call out the direction
of the iguana, its relative position to the group, and attempt to
predict its next move. "It's moving towards Alli!" "Jim,
move to your right!" "Stop! No one move!" Commands
are interrupted with oft-repeated questions of "Where is it?
Which way is it going?" Our previous plant identification lessons
pay dividends and make tracking iguanas easier when students can
identify the island flora drooping above the lizards. Once an iguana
is within catching distance, a net is hurriedly dropped and students
rush to harmlessly restrain it before returning to base camp for
processing. Although easy in theory, many attempts end with frustrated
grunts and panted sighs as most
iguanas get the last laugh and scramble away through the underbrush.
Base camp
consists of a grotto etched within a limestone wall that offers
some protection from the early morning sun. Iguanas are weighed
and measured before a PIT tag is injected beneath the right dorsolateral
side
for long-term identification. A PIT tag is unique to each animal
and is approximately the size of a grain of rice. It is magnetized
as a scanner is swept over causing a series of numbers and letters
to be displayed. It is
always a thrill to catch an animal whose PIT tag reveals its first
capture date from several years prior. Lastly, the iguanas are beaded
through their dorsal crest with a unique combination of colored
glass beads. The beads make identifying iguanas from a distance
relatively easy.
Unfortunately,
once the sun arcs directly above our heads, shade is hard to find
and the island can become unbearably hot. Thankfully, when the iguanas
retreat into the protective shade of overhanging foliage, we glide
back to the R/V Coral Reef II for a lunch and water pit stop before
continuing in the late afternoon.
This has
been the most productive Shedd trip, with 30 iguanas being caught
in 1.5 days. Thirteen of those iguanas were either first-time or
multiple recaptures going back many years. These data will be used
for future growth
and survivorship modeling. In addition to capturing iguanas, the
students also gained experience with estimating animal populations
by walking (often crawling) island-wide transects. Our population
estimate is 325 iguanas and
we hope
it stays that way. Unfortunately, the 2001 Shedd group discovered
goats that were released on the island by fishermen from a nearby
settlement. We contacted the government to remove the animals, as
goats can
compete directly with iguanas for food. This morning we discovered
that the goats are still on the island. Although disheartening,
we will redouble our efforts to have them removed.
After a
very successful two-days, we weighed anchor and swept back north
to Hawksbill Cay. The trip was relatively uneventful as exhausted
students hit their bunks or the top deck for a well-deserved nap.
The Gaulin
Cay iguanas will have a few days' respite before the next group
of students descends upon them early next week. Expectations for
those students are high.we're all hoping for a new catch record.
The more we catch, the more we know. We might count the iguanas,
but the iguanas are really counting on us.
May
20, 2003
A
Sunrise Search for White-tailed Tropicbirds
Reporting
from the Field: Rachel Gross, Public Programs Manager, John G. Shedd
Aquarium
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| White-tailed
tropicbird
Credit: Shedd Aquarium
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White-tailed
tropicbirds are arguably the most beautiful birds in the Bahamas,
maybe even the world. However, much of their natural history remains
a mystery. Lucky for us, one tropicbird colony is located right
in the middle of the Exuma Cays Land and Sea Park on an island known
as Warderick Wells. A regular stop on our annual journey.
At sunrise
today we headed ashore in search of the tropicbird burrows, in which
we hoped to also find chicks or eggs and maybe even an adult or
two. We were accompanied by two bird biologists from the University
of North Carolina at Chapel Hill, Will Mackin and Matthew McKown.
Mackin and McKown are currently studying a colony of Audubon Shearwaters,
another species of sea bird, at Long Cay, located just north of
Warderick Wells.
Tropicbirds
nest in the pockmarked limestone in holes about 20 cm wide. Often
these holes are partially or completely covered with brush, which
offers protection from predators and direct sunlight. Locating tropicbird
burrows is more of an auditory exercise than a visual one. A team
of budding bird biologists makes a fair amount of noise traipsing
across the limestone. Hungry chicks respond to these creaks and
crunches with a high- pitched scream, instantly giving their position
away. The team crowds around, wielding cameras, calipers and baby
bird-sized mesh bags and scales. The “oohing” and “ahhing”
commences as the white, furry fuzz ball is gently removed from his
rocky home. The team works quickly, records the bird’s metrics
and deposits him in his original spot.
We continued
on discovering three adults sitting on eggs in addition to the ten
or so adults that were flying over the colony. (Editor’s note:
Another moment of comic relief arrived when one inexperienced and
excited birder misidentified a five gram hermit crab for a 275 gram
tropicbird chick. In his defense, they are both white and black.
An honest mistake!) Mackin seemed pleased with the condition of
the bird population at Warderick Wells. But things haven’t
always looked so promising for these stunning creatures.
About five
years ago, Mackin noticed several tropicbird carcasses strewn around
the colony, and he continued to see this trend in mortality over
the next couple of years. Mackin discussed his observations, concerns
and suspicions with the Exuma Cays Land and Sea Park warden, who
also makes his home, year round, at Warderick Wells.
The warden
is responsible for enforcing the anti-poaching laws throughout the
180 square mile park—a big job from one man and a small army
of volunteers. The park warden has the misfortune of dealing with
unscrupulous, law breaking fishermen, and reptile, bird and plant
poachers. Needless to say, he has made an enemy or two along the
way. So for peace of mind, protection and some good ol’ canine
companionship, the warden has kept dogs on the island for the past
several years. About the time the dogs showed up, so did the dead
tropicbirds. The warden sincerely needs his dogs, yet the colony
can’t withstand the pressure—a contemporary conservation
conundrum, right in the middle of a national park.
And so,
recognizing the complexity of the issue, Mackin is working with
the warden and his volunteers to continue monitoring the colony
and to curtail the dogs’ access to the birds. Today the colony
looked good—with several adults in the air, parents on eggs
in their burrows and a new, screaming hungry chick in his hole.
Warderick Wells is prime real-estate for a rebounding population
of tropicbirds, which leaves us hopeful that next year, we’ll
find evidence of a healthy, growing population.
May
18, 2003
Bush
Hill and Little Wax Cay: A Full Day on Land and in the Water
Reporting from the field: Rachel Gross, Public Programs Manager,
Shedd Aquarium
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The
Shedd Crew in the field
Credit:
Shedd Aquarium |
Welcome
to the Exuma Cays Land and Sea Park, the world's oldest national
land and sea park. The park encompasses approximately 180 square
miles in the northern Exumas, and includes 15 major cays (pronounced
"key") and several smaller ones. Everything in the park is protected-the
islands, vegetation, sediment, water and wildlife. There is no
commercial development and only a few privately owned inhabited
islands.
Choppy waters made the transit from our previous anchorage an exciting
boat ride for some and a nauseating one for others, but the R/V
Coral Reef II deposited us safely and gently at our desired destination,
the safe harbor
of Bush Hill and Little Wax Cay. This area forms the northern most
border of the land and sea park and boasts some of the most beautiful
blue water and white sand beaches in the whole of the Exumas.
The boat steadied, the students brightened and we headed out for
our first adventure of the day-a hike to the top of Bush Hill.
It's a moderately challenging trek to the top, with planned stops
every so often for terrestrial plant review sessions. By now, the
students can identify about twenty species of Bahamian plants.and
that's not including the algae!
With sweat running in their eyes and brush scratching their shins,
it was apparent that the students were questioning the value of
this particular activity. The reward came and the fog of doubt
lifted as we ascended to the
top. A steady ocean breeze cooled us and the view took away what
little breath we had left. We've included a group photo taken at
the top of Bush Hill earlier today-just a sample of Mother Nature's
gift to this group of
awe inspired explorers. (Note: the Shedd Aquarium's R/V Coral Reef
II can be seen in the background.)
The return trip down Bush Hill meant we were ready for a hearty
lunch and short rest before gearing up for an afternoon of seagrass
monitoring and sand bar exploration. Notable species accounts from
today include conch
fish, fringed filefish, Nassau grouper, spiny lobster, and a needlefish
that shot out of the water and nearly impaled one unsuspecting student!
No need to worry-he's fully recovered from the incident and the
rest of the crew has
finally stopped laughing!
Our day concluded with a short boat ride back to Little Wax Cay
to observe the endangered Bahamian hutia (pronounced "hoo-tee-uh")-one
of only two endemic mammals in the Bahamas (the others are bats).
"What are hutia?" you ask. Hutia are large, nocturnal, herbivorous
rodents that bear a strong resemblance to guinea pigs. Observing
these shy, skittish creatures requires a sharp eye, slow, quiet
movement and restricted use of a
flashlight. Tonight, the hutia hunt produced a cacophony of loud
whispers, crunching palm leaves, buzzing mosquitoes, and scurrying
paws. It was a good night; everyone got to see a hutia. To see
an endangered Bahamian hutia is a thrill-an indescribable and uniquely
Bahamian experience. And one I don't think these students will
soon forget.
May
17, 2003
Exuma
Islands, Bahamas
Reporting
from the field: Rachel Gross, Public Programs Manager, John G. Shedd
Aquarium
This is a story of an annual journey: a yearly pursuit of knowledge,
experience and a quest to conserve a species or two. For the next
two weeks, Shedd Aquarium's research vessel, the R/V Coral Reef
II will serve as a floating classroom and laboratory for 16 eager
college students from Chicago. The Coral Reef II, along with her
three masterful crewmembers, will transport these students, their
instructors and their cargo from Nassau through the northern Exuma
archipelago. By the end of their odyssey, these students will have
encountered hundreds of species of plants, reptiles, amphibians,
birds, fish, coral and other marine invertebrates. Their field
notebooks will be filled with pages of wildlife observations, experimental
protocols and descriptive narratives of their own unique experiences.
After a semester's worth of course work and an ample layer of sunscreen
(SPF "the higher, the better"), they're ready to dive-in!
Accompanying these brave new explorers will be two teams of seasoned
field biologists. One team of behavioral ecologists investigating
a depleted population of sea birds known as Audubon shearwaters,
and the other, conservation biologists studying endangered Bahamian
iguanas.
The Exumas decorate the Atlantic Ocean like a string of delicate
pearls embellishing a seemingly endless bolt of flowing turquoise
silk. The tropical climate and striking contrast of white on shades
of blue and green may seem like an idyllic landscape for work or
pleasure, but don't be fooled. The Exuma Islands are beautiful,
indeed, but these students and researchers have their work cut out
for them.
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