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The wisdom of our fathers is sometimes embodied in what we call old
saws, to wit, "Many hands make light work," to which the iconoclast
retorts, "Too many cooks spoil the broth." And when we come to the
phrase, "As useless as a last year's bird's nest," we must reply,
"Circumstances alter cases." For many a bird's nest of yesteryear still
has its use; some a biological use to other birds; some to feed and
clothe man.
SUBLEASES The snug, secure cavity that a woodpecker chisels in some
tree trunk for its nest will last for many years, a shelter in which
tree swallows, house wrens, screech owls, bluebirds, or wood mice
may make headquarters and use as a nursery. In the strange forests of
saguaro, a giant cactus of southern Arizona, the nest cavities of the
gila woodpeckers and the gilded flickers in the cactus trunks seem
necessary for the presence of many nesting birds. Without them the
birds would have to go elsewhere for cavities in which to nest. In old
woodpecker nest cavities the elf owl, pigmy owl, screech owl, sparrow
hawk, ash-throated flycatcher, martin, and crested flycatcher commonly
nest, and cactus wrens and even Lucy's warbler may use them. Their use
is not confined to birds alone, for scaly lizards, snakes, rats, and
mice have been found in them. In the Argentine there is a woodhewer
that appears to depend on the domed mud nest of the red oven-bird for
its nesting sites. It takes over a recently vacated or an old nest of
the oven-bird and lines it with grass and feathers for its own use. In
Africa and Madagascar the great domed nest of the hammerkop stork may
find a secondary use in sheltering barn owls.
SANDPIPERS AND EAGLES But it is not only burrows and domed nests that
when deserted by their original occupants are used by other birds. The
solitary sandpiper of our northlands belongs to a group in which nest
building is reduced to a minimum, usually little more than a hollow
in the ground with a few bits of material added. But the solitary
sandpiper, and the green sandpiper of the Old World have broken with
tradition and customarily lay their eggs in the abandoned nest of some
thrush. Our great homed owl is another bird that may use the discarded
nest of a crow or hawk for its eggs and young. And age in the eagle's
nest means little to the eagle. Frances Herrick, the noted chronicler
of the life of the American bald eagle, writes of one nest in the
crotch of a lofty tree that had been in use for thirty-six years. Each
year more material was added until the nest became 12 feet high, 8½
feet across the top, and was estimated to weigh 2 tons.
Man has found, among others, the following two direct uses for two
kinds of birds' nests: one he uses for food; of another he makes
covering for himself.
The swift's nests used for food have been discussed in another chapter,
"Birds' Nests and Their Soup," so here I will only tell of the use of
birds' nests as human covering.
EIDER-DOWN BLANKETS An eider-down has come to mean a comforter, a
sleeping bag, or even a padded jacket. But to an ornithologist eider
down still has its older meaning: the down of an eider duck. It is this
material gathered from the eider ducks' nests which forms the article
of commerce. The eider's nest may contain grass, seaweed, and sticks,
but it is notable for the blanket of down on which the eggs rest, and
with which the female covers the eggs when she leaves them. This down
is plucked from the breast of the female. If it is taken from the nest
she replaces it with more, and it is on this principle that harvesting
of the down is carried out. On islands and islets in the northern part
of the North Atlantic eiders nest in great numbers in dense colonies.
Some of these are jealously guarded by the local inhabitants, who
gather the first blanket of down from the eggs, and later, after the
eggs have hatched, gather the second crop of down with which the female
has replaced the first to guard her eggs against the inclement weather
of those boreal latitudes. Each nest may yield an ounce or so of the
precious down, which is carefully cleaned and sent to market. It is
this material, extremely light, extremely elastic, and one of the best
non-conductors of heat, which finally becomes the important part of
real eider-down comforters, sleeping bags, and padded jackets.