An otter trail

February 20.

P. M. — Up Assabet. 

See a broad and distinct otter-trail, made last night or yesterday. It came out to the river through the low declivities, making a uniform broad hollow trail there without any mark of its feet. On reaching the river, it had come along under the bank, from time to time looking into the crevices where it might get under the ice there, sometimes ascending the bank and sliding back. 

Commonly seven to nine or ten inches wide, and tracks of feet twenty to twenty-four apart; but sometimes there was no track of the feet for twenty-five feet, frequently for six; in the last case swelled in the outline. 

Having come down as far as opposite the great white on the hill, it returned on its track and entered a hole under the ice at Assabet Spring, from which it has not issued.

H. D. Thoreau, Journal, February 20, 1856

See  March 6, 1856 ("On the rock this side the Leaning Hemlocks, is the track of an otter.”);April 6, 1855 ("it reminds me of an otter, which however I have never seen."); February 20, 1855 (among the quadrupeds of Concord, the otter is "very rare.”); February 4, 1855 ("See this afternoon a very distinct otter-track by the Rock”); January 30, 1854 ("How retired an otter manages to live! He grows to be four feet long without any mortal getting a glimpse of him”).