Swallows, in hawking through the air for insects, do not snap their game
up as do the true flycatchers. Their mouths are little nets which they
drive through the air with the speed of airplanes. A few mornings ago
the air was cold, but it contained many gauzy, fuzzy insects from the
size of mosquitoes down to gnats. They kept near the ground. I happened
to be sitting on the sunny side of a rock and saw the swallows sweep
past. One came by within ten feet of me and drove straight on to a very
conspicuous insect which disappeared in his open mouth in a flash. How
many hundreds or thousands of such insects they must devour each day!
Then think of how many insects the flycatchers and warblers and other
insect-eating birds must consume in the course of a season!