Birds with whom the struggle for life is the sharpest seem to be more
prolific than those whose nest and young are exposed to fewer dangers.
The robin, the sparrow, the pewee, etc., will rear, or make the attempt
to rear, two and sometimes three broods in a season; but the bobolink,
the oriole, the kingbird, the goldfinch, the cedar-bird, the birds of
prey, and the woodpeckers, that build in safe retreats, in the trunks
of trees, have usually but a single brood. If the boblink reared two
broods, our meadows would swarm with them.

I noted three nests of the cedar-bird in August in a single orchard,
all productive, but all with one or more unfruitful eggs in them.
The cedar-bird is the most silent of our birds having but a single fine
note, so far as I have observed, but its manners are very expressive
at times. No bird known to me is capable of expressing so much silent
alarm while on the nest as this bird. As you ascend the tree and draw
near it, it depresses its plumage and crest, stretches up its neck,
and becomes the very picture of fear. Other birds, under like
circumstances, hardly change their expression at all till they launch
into the air, when by their voice they express anger rather than alarm.

I have referred to the red squirrel as a destroyer of the eggs and
young of birds. I think the mischief it does in this respect can
hardly be over estimated. Nearly all birds look upon it as their
enemy, and attack and annoy it when it appears near their breeding
haunts. Thus, I have seen the pewee, the cuckoo, the robin, and
the wood-thrush pursuing it with angry voice and gestures. A friend of
mine saw a pair of robins attack one in the top of a tall tree so
vigorously that they caused it to lose its hold, when it fell to the
ground, and was so stunned by the blow as to allow him to pick it up.
If you wish the birds to breed and thrive in your orchard and groves,