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HOUSTON CHRONICLE (Texas) 22 February 06 Diamonds of the not-so-deep - Most go a lifetime without seeing one, but Texas diamondback terrapins are some of the most intriguing creatures to call the Lone Star State home (Shannon Tompkins)
Habitués of Texas bays and estuaries can be excused if they have never seen or even heard of diamondback terrapins, an amazingly beautiful and interesting wild resident of the coast.
That Forest McNeir never saw another of these fascinating animals after his encounter with them on the Vingt et-un Islands is an indication of the reptiles' rarity and reclusiveness.
McNeir grew up on Galveston Bay in the last quarter of the 1800s, commercially hunting waterfowl and alligators in the marshes and bays, foraging along the bayshore and islands, oystering on the reefs and generally crisscrossing the whole fringe of the sprawling bay system.
If diamondback terrapins eluded his well-honed gaze, today's anglers, hunters, boaters, birders, paddlers and other bayshore visitors are not likely to see them, either.
But they are there. Certainly not in the numbers of a century ago or in most of the places they once dwelled. But diamondback terrapins still haunt isolated reaches along fringes of the bays, perhaps as far south as Baffin Bay and maybe even beyond.
There is a lot of "perhaps" and "maybe" associated with diamondback terrapins. And a lot of "we don't know," too.
"They are very elusive," said John Huffman of the U.S. Fish and Wildlife Service's ecological services office in Clear Lake. "Also, there has been very little in-depth study done on terrapins (along the Texas coast)." Wildlife scientists have minimal information on the natural history of Texas diamondback terrapins or the turtles' population.
"A lot of what we think we know about diamondback terrapins is based on research done on the East Coast," said Huffman, whose graduate work focused on terrapins in Galveston Bay.
The species — of which the Texas diamondback terrapin is one of seven subspecies — has a native range along the East Coast as far north as Cape Cod, Mass., and along the Gulf Coast to near Corpus Christi.
Diamondback terrapins are unique and tied inexorably to the thin band of brackish and saltmarsh habitat along the coast. Sea turtles not included, the terrapins are the only one of the world's 270 or so turtle species that lives exclusively in this link between brackish and saline environments.
"They are like rails and seaside sparrows in that they live only in this single, relatively small ecosystem," said Matt Whitbeck, a biologist with the Anahuac National Wildlife Refuge.
Unlike rails and sparrows and other wildlife in the coastal marshes and bayshores, though, terrapins are very rarely seen.
"There are people who have lived on the coast their whole life and have never seen a terrapin," Huffman said.
Terrapins live quietly among the seapurslane, saltwort and thick marsh grasses, feeding on fiddler crabs, periwinkles and fish and even plucking low-hanging berries on sandy uplands. They swim quite a bit, often to oyster reefs where they bask or forage; this aquatic lifestyle can be inferred from the oversized, webbed back feet they use to propel themselves against the currents in bayous, cuts, drains and the shallow bay waters they frequent.
They are relatively small animals — an adult female measures seven to nine inches from front to back of her carapace, and an adult male no more than five inches or so.
That carapace — the top of the terrapin's shell — is what gives it the "diamondback" moniker. The shell is decorated with segmented scutes that hold concentric grooves that
look much like faceted diamonds.
"They are very colorful creatures," Huffman said. "Each one is different."
Carapaces can be olive or brown or black and have orange highlights or edges.
The plastron — the bottom shell — often is pale yellow or black trimmed in bright orange.
But its the terrapin's skin that can really catches the eye. It's typically a light gray that sometimes tends toward bluish, typically speckled with black markings that can include flecks, dots, stripes or spots.
Terrapins are like snowflakes; no two look exactly the same and each is a jewel.
Along the Texas coast, the reptiles are encountered almost as rarely as snowflakes.
Whitbeck has worked at the Anahuac refuge since 1997, spending more hours in the marshes and bayshore than many dedicated anglers or hunters do over decades.
Until last week, he had never encountered a live diamondback terrapin.
He had found dead ones, though.
While participating in Texas' annual volunteer cleanup of abandoned crab traps last year, Whitbeck found nearly two-dozen dead terrapins in traps along East Galveston Bay. Two traps within about 30 feet of each other held 20 dead terrapins; some of the turtles had been dead for months, and others were fresh kills.
He had stumbled upon what East Coast terrapin researchers have long documented as a common cause of terrapin mortality. Diamondback terrapins foraging in the shallows often enter crab traps to feast on the carrion used as bait, then get stuck. Unless the top of the trap remains above water, the terrapins drown.
In McNeir's day, the greatest threat to terrapins was directed commercial harvest. The little terrapins were considered a delicacy — a soup made from terrapin was popular among the elites, and commercial harvest of wild terrapins was big business, as the McNeirs discovered when they got the fabulous sum of $4 a dozen.
But overharvest, changes in tastes, Prohibition (which denied cooks the wine for making terrapin soup) and the Depression combined to collapse the commercial terrapin market by the mid-1930s.
Terrapin populations, depressed from commercial overharvest, soon had other problems. Accelerating coastal development, particularly along bayshores, began eating into their habitat — specifically the upland habitat the animals needed for nesting sites.
In the 1940s, the wire crab trap was developed, and its use exploded throughout bay systems.
Terrapins were, and continue to be, unintended victims.
Last Friday while participating in this year's clean-up of derelict crab traps, Whitbeck again found diamondback terrapins in the contraption.
But this time, they were alive. One trap, which the current had serendipitously turned on its side so that a portion remained above water at high tide, held four live diamondbacks.
They were the first live terrapins Whitbeck saw in Texas.
After extracting the mild-mannered, strikingly marked terrapins from their prison, Whitbeck and fellow trap cleanup volunteer Beth Rigby carried them to the edge of a shallow finger of water and released them.
The terrapins lazily entered the water, effortlessly swam over a muddy bottom crisscrossed with the tracks of herons and other shorebirds, lumbered up the other side of the waterway and crawled into the cordgrass, where they immediately vanished.
http://www.chron.com/disp/story.mpl/sports/3678959.html