46 THE MAMMALS, REPTILES, AND FISHES OF ESSEX.
their habits. I have heard from an elderly friend that on
one occasion, when the ground was completely covered with
snow, he tracked an otter for some miles, upon its passage
from pond to pond. This distance it had travelled during
the night. The district was Dengie Hundred, and the time
that when ponds containing fish, or at all events eels, were
much more abundant than now. As is well known, almost
every field formerly had its clay-pit or pond, now drained and
filled up in consequence of changes in agriculture.
A very interesting article * has been published by Mr.
John Watson, on the food of the Otter. The author
clearly shows that, as the dietary of this animal is extremely
comprehensive, its depredations upon the stock of fish
contained in our rivers cannot really be serious.
Genus Mustela, Linn.
Mustela vulgaris, Erxleben. Common Weasel.
In spite of persecution, this small animal is common in all
parts of Essex, and especially on the marshes, where I have
found abundant evidence in casts that it not unfrequently
forms the food of Herons.
The Weasel may be distinguished at a glance from the Stoat
by the colour of its tail, which is of the same reddish-
brown tint as the upper surface of its body. An additional
distinction may be usually found in the smaller size of the
Weasel. This character, however, is not immutable, as I have
seen Weasels quite as large as an average Stoat, and full-grown
Stoats as small as under-sized Weasels.
This is another of the so-called " vermin," and is ruth-
lessly destroyed whenever it is found. This, in my opinion,
is a great mistake, since its prey consists chiefly of the smaller
* " Water Poachers," Nineteenth Century, Oct. 1889 ; cf. Essex Nat., vol. iv.,
p. 84.