nce. Remembering that it is _6 inches long_ a
practical though rough division of wild birds may be made as follows:--

1. Birds smaller than the _English Sparrow_.
2. Birds about the size of the _English Sparrow_.
3. Birds decidedly larger than the _English Sparrow_.

If a few general characteristics of the principal bird-families be kept
in mind, and these are quickly and almost unconsciously learned, the
identity of a strange bird may usually be narrowed down to a few
possibilities. For example:

*Woodpeckers climb up and down the trunks of trees bracing with their
tails and tapping the bark vigorously;

*Nuthatches are smaller than woodpeckers and have much the same habit of
climbing up and down tree-trunks but with a freer wig-wagging
motion, often descending head downward;

*Flycatchers sit erect with drooping tails, watching alertly for insect
prey upon which they pounce in mid-air, afterwards returning to
their perch;

*Swallows skim through the air in graceful and long sustained flights;

*Sparrows have stout seed-cracking bills, feed upon the ground, seldom
fly high or far at a time and are for the most part fine
songsters;

*Warblers are tiny, tireless, gaily-colored explorers of the twigs of
trees and bushes;

*Kinglets are smaller than warblers and quite as restless in their
motions, but arrive earlier in the migration;

*Wrens, with tails erect, slip mouse-like about brush heaps, crevices and
bushes, though often perching in sight while singing;

*Thrushes, who with the exception of the _Robin_ and _Bluebird_ are very
plainly dressed, run about on the ground stopping suddenly in a
listening attitude. When singing they fly up to some perch,
although many of the unrivaled singers of this family are
silent during their brief sojourn in city parks;

*Vireos are most at home on the boughs of trees and sing freely as they
glide in and out among the leaves to feed.

Female birds can usually be identified after the adult males have been
seen, although the females and young of many species are obscurely marked
or quite different from the adult males, a fact especially true of the
warblers. Immature birds are not considered in the present scheme of
study since they are a source of confusion to the beginner and occur in
any considerable number on