Sebonac Creek Sightings

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Last week’s paddling trip was a field trip to the Sebonac estuary with Southampton High School’s Advanced Placement Environmental Science classes. It was a perfect day to be outdoors and on the water: sunny and warm, and no wind.

Before we even launched, as the students were donning PFDs and unloading boats, we were treated to a number of interesting sightings. A large flock of ruddy turnstones fed feverishly on the shoreline of Tern Island, just opposite our launch spot. I guessed that they were probing the wet sand for the small but energy-packed eggs of the horseshoe crab, and made a note to make that our first stop.

Many of our small shorebirds lack a colorful and distinctive plumage and are difficult to identify. But the ruddy turnstone, especially in its highly contrasting calico-colored breeding plumage, is one of the easiest shorebirds for beginner birders to ID. While many of our local breeding birds have already incubated eggs and are rearing young, this flock of more than 60 birds still has a long voyage—between 1,500 and 2.000 miles—north to its nesting grounds in the high Arctic. They are not behind schedule and can afford to linger here to fatten up on horseshoe crab eggs and tiny invertebrates living in the intertidal zone just under the surface of the beach sand and gravel, as their nesting areas are still in the grip of winter. Temperatures at Baffin Island, their closest nesting area, hovered around freezing as of this writing.

In contrast to the turnstones’ schedule, a pair of osprey nesting near the inlet already had chicks. One of the pair flew overhead with a freshly caught fish. The loud chirping that soon followed announced its landing and feeding of hungry young, which, on a rich diet of fish, will soon be as large as the adults.

Just beyond the kayaks, perched at the waterline, a horseshoe crab’s upper shell briefly emerged from the water before it turned and was swept away by the inlet’s swift ebb current. Horseshoe crabs have six paired appendages modified for various tasks. The pair located farthest forward are short, tipped with pincers, and are strictly for grabbing food items and passing them back to its centrally positioned mouth.

Among males, the next pair of appendages is modified to grab and securely hold the rear edge of a female’s shell, and this is used solely for mating (fertilization of the eggs is external). Among females, this second pair, as well as the third, fourth and fifth pairs of appendages among both sexes, are relatively long and pincer-tipped, and serve two functions: walking along the bottom, and grabbing potential food items.

The last pair of appendages lacks pincers. It ends in a series small flattened structures encircling a single, pointed tip that somewhat resembles the tip of a ski pole, and that serve a similar function. But instead of providing purchase in soft snow, the horseshoe crab’s “ski pole” allows it to push off in soft bottom sediments that its other appendages would sink deep into and cause it to flounder. The flattened structures also have the ability to retract, not unlike a beach umbrella folding along its supporting pole, and in this way they enable the horseshoe crab to swim. I’ve never witnessed this, but apparently it will swim upside down.

Not far from the horseshoe crab, another large, oddly shaped creature appeared from the deep channel and made its way toward shore where we stood. This was a sea robin, and we were lucky enough to witness it flush a small fish from the bottom sediment, pursue it surprisingly slowly toward the surface, open its gaping mouth and swallow it whole!

Our first stop was the beach where the turnstones had been feeding, and there we confirmed that they were probing the sand for horseshoe crab eggs. On Tern Island, the students were able to locate a shorebird that is more often heard than seen: the piping plover. Although it does not seem especially camouflaged for the open beach environment, with its conspicuous black neck ring and orange bill, it seems to disappear from sight when it stops moving.

Back on Sebonac Creek, a huge sandy shoal located off the southwest tip of Cow Neck held another large flock of ruddy turnstones, as well as a half dozen of our largest plovers in their striking breeding plumage: the black-bellied plover. This shorebird is also bound for the high Arctic to mate and nest.

The large shoal is new to the area, and too shallow to pass over at low tide, even in a kayak. This must be a feature that was created by Hurricane Sandy.

Back at the Sebonac Inlet Road beach, while waiting for the next class to arrive, I watched a large turtle ride the outgoing tide from the creek into the bay. This was most likely a female diamondback terrapin, perhaps coming or going to her favorite nesting spot.

June is nesting season for our local turtles, and the month when they are most likely to be found crossing roads. Please keep an eye out for them while driving, and, if possible, expedite their crossing and get them out of harm’s way by moving them off the pavement to the shoulder they were headed for.

It is illegal to collect our local turtles, and releasing them far from their established territories can create more problems.

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