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IN THOREAU'S WOODS

By Peter Arnold, Biology Teacher, Middlesex School

Published in the magazine, Massachusetts Audubon , Vol. 52, Number 3 (April 1968) pages 2-9.

Henry David Thoreau said of what now is known as Estabrook Woods:

"What a wild country and rich domaine that Estabrooks Country! Not a cultivated, hardly a cultivatable field in it, and yet it delights all natural persons, and feeds still more . . . "

Estabrook Woods today "feeds still more," indeed! Some seven hundred acres of this uninhabited woodland and fifty acres on the other side of the Concord River, known as the Pickman Lands, form Harvard University's Ecological Field Station in Concord, Massachusetts.

Thoreau's comments of 1857 were expressed in more modern terms by Thomas Flint of Concord, who with Lawrence Terry [then*] of Harvard, headed the fund drive to create the station. Said Flint, "This program promises research on subjects essential to man's ultimate survival while at the same time preserving the natural beauty of the Estabrook Woods as a sanctuary."  

[*Ed. note in April 2000: The interests and personnel of both Harvard and Middlesex School were intertwined in this enterprise: Mr. Terry was headmaster of Middlesex School at the time the idea of the Concord Field Station for the MCZ took shape in the early 1960s; then, at his retirement in the mid-1960s, he co-chaired this campaign for its creation at the time when both he and Nathaniel Davis, chair of Middlesex trustees, led the MCZ Visiting Committee.]

The Estabrook Woods area of the Harvard Station abuts one hundred acres held by Middlesex School and is adjacent to the Great Meadows National Wildlife Refuge, which runs through the Concord and Sudbury River Valleys. The Pickman Lands adjoin the national refuge. The land itself and its neighboring acres make the Concord Station one of the finest tracts in the nation for wildlife and wildlands study and assure its continuing quality.

The research station became a reality in 1966 when Harvard alumni and foundations raised $500,000 to buy and maintain it.

One of the happiest sounds heard in New England each spring is the clear, high-pitched song of the spring peeper, our smallest frog. At first the sound is a hesitating chorus but with each passing day the song grows louder and more insistent. This tiny creature is truly the harbinger of spring.

At Estabrook Woods in Concord, this nightly chorus marks the renewal of the life cycle among amphibians and reptiles that help to make the woods, ponds and nearby meadows exciting places. Most visitors to this extraordinarily rich faunal area are soon well aware of the various birds and mammals but overlook the equally interesting populations of amphibians and reptiles.

Perhaps the most common woodland amphibians are the red-backed salamanders (Plethodon cinereus ) which spend the majority of their time searching for prey in and under dead pine logs. These animals with their close relatives the dusky salamanders (Desmognathus fuscus ) are lungless salamanders. They fulfill their respiratory requirements by literally breathing through their skins which must be kept moist at all times. Keen predators, they in turn are hunted by that beautiful little reptile, the ring-necked snake, who is seldom far away.

Along with the smallest of our salamanders mentioned above, there also exist two species of mole salamanders, the largest salamanders found here. These mole salamanders, which spend their time burrowing through the soil in search of earthworms, are seldom seen except during their breeding season in late March or early April. At this time if one visits the small, cold ponds hidden away in the woods, he will find two interesting salamanders. One is the spotted salamander (Abystoma maculatum ). Most of us have assumed for years that the other species was the Jefferson's salamander (Ambystoma jeffersonianum ). (Closer study, however, may disclose that this second species is the northern blue-spotted salamander (Ambystoma laterale ), which is both close in relationship and close in appearance to Jefferson's salamander. The Jefferson and blue-spotted salamander have been confused to the extent that the New England ranges of the two species now are being reviewed. In a surprising number of instances, supposed Jefferson populations have been identified as blue-spotted. We hope that our studies this spring will clarify the situation in Estabrook Woods. ) For a few nights, the ponds will be filled with these creatures. But with the laying of their egg masses they will retire once more to the surrounding woodlands and disappear underground.

While most of our salamanders in the Estabrook Woods are terrestrial, there are two species that spend their lives in or near water. The more difficult to find of these is the northern two-lined salamander (Eurycea bislineata ) which prefers fast-running cold streams in which to breed. These stream-lined little creatures can be found only with patience, as it becomes a case of now-you-see-them-now-you-don't when the rocks and debris of their fast-moving environment are disturbed. When they have finished egg-laying, they too will move ashore, but only as far as the stream edge. At this time they become even harder to find.

While the northern two-lined salamander prefers fast-running water, the other species of aquatic salamander, the red-spotted newt (Diemictylus viridescens ) prefers the quiet of ponds. This shy animal, hiding by day under the dead leaves and other debris that covers the bottoms of our New England ponds, can most easily be seen at night. It will generally freeze when a flashlight is shined on it, thus making it a comparatively easy salamander to catch. Newts make excellent aquarium pets if taken care of properly. It is hard to believe that this green-colored salamander with the vermilion spots and yellowish belly is one and the same with the red eft. The eft is the beautiful, brick-red land form of the newt that one finds occasionally while walking in the woods. Not all newt populations go through this transitional stage, which poses an interesting question to any budding herpetologist. In my travels here and in the Harvard Forest in Petersham, I have observed that the red eft stage is far more common there than here. The difference in vegetation might have something to do with this.

Living in close quarters with the salamanders and competing with them for breeding areas and sometimes for food are the frogs and toads. These amphibians are better known and more easily seen than salamanders. Because they are so familiar to most of us, they have been ignored as interesting subjects of field study. However, for anyone with patience, a day at a quiet New England pond can bring enjoyment in observing these animals and their behavior. Their life history varies from species to species even though they look so alike, particularly as tadpoles. Usually salamander tadpoles are lumped unceremoniously together with the frogs. Most of our species tend to be aquatic but we do have some that prefer the woods to the water. In the Family Ranidae , we have five species that can be found without too much trouble in or around the Estabrook Woods. These are the bullfrog (Rana catesbeiana ), green frog (Rana clamitans ), pickerel frog (Rana palustris ), leopard frog (Rana pipiens ) and wood frog (Rana sylvatica ). The first three live their lives in the ponds while the leopard frog prefers the wet meadows and the wood frog retreats back to the woods following the breeding season. Our two species of Hyla , the spring peeper (Hyla crucifer ) and the gray tree frog (Hyla versicolor ) while numerous during the egg-laying period, become hard to find after the beginning of the summer. A pond can appear to be literally overflowing with peepers one night and be vacant the next. Our last two frogs, the common toad (Bufo americanus ) and the uncommon Fowler's toad (Bufo woodhousei ) round out this group of animals which help to subdue the insects that are continually battling man for control of the environment. These then are the amphibians of the Estabrook Woods and a fascinating group they are. As members of the ecosystem they contribute in helping to maintain the balance of nature that is so necessary if these woods are to continue.

As for our reptile population, while not as diverse as those found in more southerly zones, nonetheless it also has important members in Estabrook Woods. The most maligned, misunderstood and most senselessly persecuted of our reptiles are of course, the snakes. Nine of the thirteen species that inhabit New England can be found here but they seem to grow scarcer each year. Even with this protected habitat in which to dwell, the snakes have a rough road to travel. Hunted by hawks during the day, foxes and coon during the night, their worst enemy by far is man. Not only is their habitat needlessly ruined but also they are usually killed on sight. I realize that in this short paper, I cannot convert any one to my personal enjoyment in studying these fascinating animals but if I can succeed in just getting readers to leave them alone, I will feel I have accomplished something.

The most common of the Estabrook snakes are the garter snake (Thamnophis sirtalis ), ribbon snake (Thamnophis sauritus ) and water snake (Natrix sipedon ). These three reptiles are of major importance in their destruction of insects and while they do eat frogs and toads, their value to man is still far greater than is generally realized. Our milk snakes (Lampropeltis doliata ), often mistakenly killed as copperheads, are one of man's best rodent control agents and for that reason alone should not be killed. Even the common black racer (Coluber constrictor ), helps in keeping the mouse population under control. However, his blackness, his speed and generally vicious disposition when trapped are all held against him. Luckily due to their small size, the ringneck snake (Diadophis punctatus ) red-bellied snake (Storeria occipitomaculata ), northern brown snake (Storeria dekayi ) and the smooth green snake (Opheodrys vernalis ) have been able to escape man's notice. Only those who actively search for these five species will ever see them. The small secretive snakes also are of great importance in holding the insect hordes at bay. Estabrook Woods would be much less interesting without its snakes.

While the snakes are struggling for existence in the face of man's unreasoning hostility, their relatives, the turtles, seem to be more than holding their own. While turtles are killed in great numbers by cars during the breeding season when the females come ashore to lay their eggs, we don't seem to mind sharing our environment with them. Only the snapping turtle (Chelycdra serpentina ) comes in for more than his share of man's cruelty. Yet even this, the largest of our turtles, plays a role in keeping ponds clean. He does take ducklings to be sure but the loss is not as great as supposed. The painted turtles (Chrysemys picta ) and the musk turtles (Sternothaerus odoratus ), while caught by little boys as pets, enjoy a relatively peaceful existence. The other three turtles of this area, harder to find because of the destruction of their meadow habitat, are the spotted turtle (Clemmys guttata ), box turtle (Terrapene carolina ), and wood turtle (Clemmys insculpta ). The spotted turtle has become scarcer with each passing year. Box turtles and wood turtles still can be found if one has the patience to hunt and knows something about their overall life history. The wood turtle makes a good pet as it can be taught to feed out of one's hand and seems able to evince a certain amount of recognition. I cannot help but marvel every time I see the various species of turtles, as they are indeed a link to the long distant past of earth's history, relatively unchanged in structure during their trip through time.

For those amphibians and reptiles which live in the Estabrook Woods, a safe habitat now is assured for years to come. Thanks to the unselfish and untiring work of men like Thomas Flint of the Concord Conservation Commission, Lawrence Terry, headmaster emeritus of Middlesex School, Mrs. Barbara Lawrence, curator of mammals at Harvard University's Museum of Comparative Zoology, Dr. Ernst Mayr, director of the Museum of Comparative Zoology and many, many others, the Estabrook Woods have been saved from the developer's bulldozer.

These woods will now be used as a living outdoor laboratory by the ecologists of Harvard and other universities, so that man may have a better understanding of himself and the problems with which he is faced in his ever-shrinking world. The woods will remain a place of solitude and beauty for those who feel that natural beauty needs no apologies for being except to bring an enjoyment which cannot he duplicated. It is indeed comforting to realize that these unspoiled woods will continue to provide a haven for the plants and animals which make the world such an interesting place in which to live.

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