A Nature Paddle On Big Fresh Pond

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My first nature paddle of the season took place on Big Fresh Pond in North Sea last weekend. Sponsored by the South Fork Natural History Museum, the theme of the outing was “signs of spring,” and there were plenty to see during our leisurely circumnavigation of the kettlehole pond.The subaquatic vegetation was way ahead of the terrestrial plants in terms of “greenery,” with the still unfurling leaves of either spadderdock or fragrant water lily most conspicuous. Shoreside, small patches of skunk cabbage’s immense leaves and the long, narrow leaves of black willow were both readily evident but still emerging.

The most obvious flowers were those of the red maple trees growing at the edge of the pond. A question arose about the tree’s two distinct flower colors, visible from afar: those with a reddish hue and others having a yellowish color. A close inspection of a specimen with branches reaching far out over the water revealed that its lower branches had all yellow-colored male flowers, while the upper branches appeared to be red-colored female flowers. I was not aware that red maple had this arrangement, as the one growing in my front yard has perfect flowers (a flower having both pistils and stamens, or both male and female parts). I’ll have to look more closely at that.

Another common shoreside tree, shadbush, was not yet in bloom, although the large, swollen flower buds were very visible and about to open soon. This tree’s common name is derived from the notion that its flowers appear during the spring spawning run of a type of herring called shad (Alosa sapidissima). Big Fresh is the spawning grounds of another species of herring: the alewife (Alosa pseudoharengus).

This year we did not see any evidence of the alewives in the pond, but the banks of its outlet stream were littered with carcasses of the 10-inch-long silvery fish, the remnants of predation. Most were headless. It appears that when a resource is so abundant and easily caught, predators can afford to be picky about what parts they consume. In this case they seem to be limiting their feeding on the small bit of brain, and leaving the bulk of the carcass intact.

Among the fish predators visible that morning were black-crowned night herons, a great blue heron, several osprey and a small flock of double-crested cormorants. There have been many bald eagle sightings at Big Fresh over the past two years, but none during our morning paddle.

We did see lots of smaller fish in the clear shallows of the pond. These appeared to be one of the sunfishes, most likely the pumpkinseed. And we came across several clear, 1-inch-wide, 12-inch-long chains of yellow perch egg masses.

The most interesting sightings were of the pond’s reptilian inhabitants: the turtles. Painted turtles basked in the warm sun, perched atop masses of sedge, small logs, and in one case on the carapace of a large snapping turtle. Snappers tend to bask at the water’s surface with their upper shell just slightly protruding, if at all.

Basking is a behavior employed by many so-called “cold-blooded” species that do not have the ability to internally regulate their body temperature: turtles, snakes, lizards, toads and frogs. Some warm-blooded species, or endotherms, such as seals, also bask to conserve energy.

The pond’s water temperature registered 58 degrees Fahrenheit last Saturday, just a few degrees below the threshold for many turtles’ digestive enzymes to function efficiently. Their dark-colored shells could absorb solar energy and boost their internal temps well above that threshold on a sunny day. Open water swimmers take note: This and other shallow freshwater ponds (e.g., Wildwood Lake) are the best places to get a jump start on training.

Near the end of the paddle, keen-eyed Doug Schmid noticed a small, dark-shelled turtle moving in shallow water along the bottom of the pond. This was a species I have only seen once before in my life, and that was in Big Fresh Pond’s outlet stream. This was the musk turtle, or stinkpot (Sternotherus odoratus).

Stinkpots are relatively small turtles with a maximum shell length of 5.5 inches. Distinctive features include two thin yellow lines on each side of the head, their pig-like snout, triangular-shaped head (when viewed from above), high-domed carapace (upper shell) and small lower shell (plastron) that leaves much of their legs exposed (as is the case with the snapping turtle).

The terms stinkpot, musk and odoratus all refer to this turtle’s ability to secrete a strong odor from a gland located near the bridge or connection between the upper and lower shells. I did not notice the yellow liquid or a foul smell while handling this animal.

Their high-domed, unstreamlined carapace is a poor design for swimming efficiency, and it is not surprising to learn that this species tends to walk on the pond bottom rather than swim. Its small plastron is hinged at the forward edge of the bridge, a design feature that provides more flexibility and agility for its limbs, enabling it to walk more efficiently than, for example, a painted turtle. Stinkpots are probably our most agile native turtle, as they have been known to climb trees and shrubs overhanging the water to a height of 6 feet!

We were able to locate a second stinkpot in the same general area. Comparing the two, we noted differences in the shape of their plastrons (lower shells) and size (length and width) of their tails and realized we had a male and a female. Neither had the characteristic algae growth on the upper shell, a form of camouflage that may have died off during the recent overwintering stage in the dark sediments of the pond bottom.

Reading up on the stinkpot, I soon realized why I have not seen this very often. First, this species is nocturnal, sitting motionless on the bottom during daylight hours. And it can remain underwater for several months without coming up for air. How? It can extract oxygen from the water through its tongue. Amazing!

Next nature paddle is on the upper portion of the Peconic River with the Peconic Land Trust on Saturday, May 9. Join me for a fun outing as we search for more signs of spring.

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