The flight of the flying squirrel

March 23.

Carry my flying squirrel back to the woods in my handkerchief. I place it, about 3.30 P. M., on the very stump I had taken it from. It immediately runs about a rod over the leaves and up a slender maple sapling about ten feet, then after a moment’s pause springs off and skims downward toward a large maple nine feet distant, whose trunk it struck three or four feet from the ground. 

This it rapidly ascends, on the opposite side from me, nearly thirty feet, and there clings to the main stem with its head downward, eyeing me. After two or three minutes’ pause I see that it is preparing for another spring by raising its head and looking off, and away it goes in admirable style, more like a bird than any quadruped I have dreamed of and far surpassing the impression I have received from naturalists’ accounts.

I mark the spot it started from and the place where it struck, and measure the height and distance carefully. 

It sprang off from the maple at the height of twenty-eight and a half feet, and struck the ground at the foot of a tree fifty and a half feet distant, measured horizontally. As the ground rose about two feet, the distance was to the absolute height as fifty and a half to twenty-six and a half, or it advanced about two feet for every one foot of descent.

Its flight was not a regular descent; it varied from a direct line both horizontally and vertically. Indeed it skimmed much like a hawk and part of its flight was nearly horizontal, and it diverged from a right line eight or ten feet to the right, making a curve in that direction. There were six trees from six inches to a foot in diameter, one a hemlock, in a direct line between the two termini, and these it skimmed partly round, and passed through their thinner limbs; did not as I could perceive touch a twig. It skimmed its way like a hawk between and around the trees. 

In order to perform all these flights, —to strike a tree at such a distance, etc., etc., —it is evident it must be able to steer.

H. D.  Thoreau, Journal, March 23, 1855

Carry my flying squirrel back to the woods in my handkerchief. I place it, about 3.30 P. M., on the very stump I had taken it from. See March 22, 1855 ("I observed a rotten and hollow hemlock stump about two feet high and six inches in diameter , and instinctively approached with my right hand ready to cover it . I found a flying squirrel in it , which , as my left hand had covered a small hole at the bottom , ran directly into my right hand ."); see also   June 19, 1859 ("A flying squirrel's nest and young . . . Saw three young run out after the mother and up a slender oak. The young half-grown, very tender-looking and weak-tailed, yet one climbed quite to the top of an oak twenty-five feet high,")

My flying squirrel 

up a slender maple springs 

off and skims downward.