THE CANVASS-BACKED DUCK. 97

cellent divers and swim with speed and
ease. They sometimes collect in flocks
of thousands, and rising suddenly on the
wing, cause a noise like thunder. When
wounded in the wing, they dive to a great
distance and pursuit is almost hopeless.
The gunners practise various plans to
obtain these ducks. Sometimes, by moon-
light, the sportsman directs his skiff
towards a flock, and keeping within the
shadow of a wood or headland, gets within
reach of many thousands among whom he
makes great havoc. In winter, when their
food is scarce, they are decoyed by holes
made in the ice, near which the sportsman
stations himself. This duck derives its
name, from the greyish-white color of the
middle of its back, resembling canvass.