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30 September 2013

The Swallow Tree - Historic Swift Roost in Vermont

Z. Thompson. Correspondence of the Traveler.
Burlington, (Vt.) June 15, 1852.

Editors of the Traveler: — Objects which are interesting to the curious and puzzling to the knowing ones, are coming to the light, almost every day, in various parts of the country. Of this class are the contents of what is technically called a Swallow Tree, which have recently been discovered in Middlebury in this State. — At the time the first settlements were made in the western parts of Vermont, these swallow trees were quite common here, and several of them are described by Dr. Williams in his history of the State. They were usually very large elms, or sycamores, having extensive hollows within and an opening in the side, at a considerable height from the ground, at which the swallows entered and made their egress. — Early each spring, and about sunrise in the morning, myriads of swallows were seen to issue from the boles in these trees and disperse themselves over the country, and, in the dusk of the evening, they were observed to return again to their common roosting places in the hollows of the trees. Thus they continued to disperse themselves in the morning and collect together in the evening, till they commenced pairing and rearing their young in the spring, and the same phenomena were also observed again just before the final disappearance of the swallows in the fall, and for a long time the opinion prevailed that they passed the winter in these trees in a torpid state. But it is now, I believe, well settled that this resort to particular trees, in early times, and to particular old chimneys in modern, as common roosting places, is only a temporary arrangement attending their arrival in spring and their migration southward in autumn.

These swallow trees, which were so common in early times, had, probably many of them, been resorted to by thousands of birds, year after year, for centuries. The natural consequence would be, for the cavities in which they roosted, to become gradually filled up with excrement cast off feathers, exuvia of insects and rotten wood, and, accordingly, trees have been found in this condition long after the swallows have ceased to resort to them. One of the kind, in Ohio, is descried in Harris Journal, and quoted in Wilson's Ornithology. The tree was a hollow sycamore, five feet in diameter, and had been blown down. Its immense hollow was found to be filled, for the space of fifteen feet, with "a mess of decayed feathers, with a small admixture of brownish dust and the exuvia of various insects."

The tree recently found in Middlebury resembled, in most respects, the one above mentioned. The tree had blown down, and had, afterwards, nearly all rotted away, leaving little remaining, excepting the feathery mass, which had filled its hollow, and which was now bedded in leaves and moss. The tree was, probably, an elm, and, judging from the size of the cylindrical mass of the contents, the diameter of its hollow must have been almost fifteen inches, which had been filled some six or seven feet. Of the materials which had filled it, about one-half consists of feathers, being, for the most part, the wing and tail feathers of the chimney swallow, (Cypsilus pelasgius Tem.). The other half is made up of the exuvia of insects, mostly the fragments and eggs of the large wood ant, and a brownish dust, probably derived from the decayed wood of the interior of the tree.

Now, while the discovery at Middlebury is, on many accounts, an interesting one, there would be nothing very remarkable in it, were the materials which had filled the hollow of the tree jumbled promiscuously and disorderly together. It would be just what we should expect to find in a hollow tree, which had been for centuries, perhaps, the roosting place of myriads of swallows. But this is not the case. As a general thing, the large feathers have their quills pointing outward at the surface of the cylindrical trees, while the plumes, or ends containing the vanes, point inward. This arrangement might perhaps arise from the nesting of small quadrupeds in the hollow, making the feathers their bed. But in addition to this, we find in various portions of the mess, in some cases all the feathers of the tail, embedded in the mass, lying in context, and precisely in the order and position in which they are found in the living swallow. In a mass of the materials, measuring not more than 7 inches by 5 and less than 3 inches thick, I could trace, at least, 5 wings and 2 tails, and on one of the wings the secondary quills were also plainly arranged in their true position with regard to the primaries. Now it is not possible to conceive that these feathers were shed by living birds in the order in which they are found. But if the birds died there, what has become of their beaks, claws and bones? We should think that these, or portions of them, would be as durable as the feathers; but I do not learn that a particle of any of these has been found in any part of the mess. How then have these been removed, while the wing and tail feathers remain in their true natural position? It could hardly be done by any violent means without disturbing them. But if done quietly, what did it? Would any insects devour the bones and not the quills? Does the formic, or any other acid, which might be generated within the hollow of the tree, decompose bone?

I shall not attempt to explain the phenomenon. I have endeavoured to state the facts, as they were kindly furnished me by my friend J.A. Jameson, Tutor in our university, who visited the locality in May; and, as ascertained by myself by a careful examination of a considerable mass of the materials, which were procured by him and presented to the University Museum for preservation, and shall leave it to others to secure for them.

July 9, 1852. Burlington Free Press 7(2): 1, new series.