2 INTRODUCTION. 
nest and attaching it to some neighboring object. I myself, 
from as near a standpoint as possible, and often aided by an 
opera-glass, observe, if I can, the female when actually upon 
her nest, since other birds may be about it, and may even 
make complaints from sympathy, or because their own nests 
are near by.!_ Should she fly too soon, I either return after a 
few moments’ absence or concealment (as I often do in prefer- 
ence to doing mischief by keeping her too long from her nest), 
or I follow her with my eye, endeavoring not to lose sight of 
her nor to confuse her with any other species, and note, so far 
as possible, all her markings, which, until I became an expert, 
I always noted down on the spot, to compare with full descrip- 
tions at home. Practice enables one to recognize many birds, 
particularly the larger ones, at a glance, and to note readily 
the most characteristic markings; but there is no objection to 
shooting hawks, which are less easily identified otherwise than 
smaller species. There are some persons who are too inaccu- 
rate to follow this method, and with such, or with those per- 
sonally unknown to you, it is well never to exchange. Males 
are generally more easily identified than females, and fre- 
quently sit upon their nests, though most often appearing 
when their mates are disturbed. Confusion may easily arise 
from two varieties of one species, but both forms rarely occur 
in the same district, and, according to a strict definition of the 
word ** variety,” can never normally do so. The only varie- 
ties (not belonging to original types) which occur in New 
England among land-birds, are the Gray-cheeked Thrush, the 
Bronzed Blackbird,? and the Red-naped Woodpecker, of which 
the first-named has been sometimes ranked as a species, and 
1TIt may be added that Cow-birds never lay their eggs but in the nests of other 
birds. See §17, LI. 
2 This bird is thought to build in holes, while the Crow. Blackbird does not.” 
