2 FIELD KEY TO THE LAND BIRDS. 
in color or otherwise are placed close together, to enable 
the student to observe their differences readily and 
quickly, and at the foot of each plate are a few remarks 
to draw attention to points of difference between birds 
that closely resemble each other. Unless otherwise 
specified, the male bird in spring plumage has-been 
chosen for representation, as in some cases he changes 
his coat later in the year, and becomes similar to the 
female. The females and young are usually similar to 
the males in shape and marking, with the black, how- 
ever, turned to gray or brown, and the other colors gray- 
ish or faded. Whenever there is a radical difference the 
female or young, as well as the male, has been repre- 
sented in the plates, and minor variations have been 
mentioned in the text. 
Some birds stay with us in the North the year around ; 
some breed here in the summer and spend the winter 
farther south ; while others are here during the winter, 
and breed to the northward in the summer; and a great 
number pass through in the spring and fall, breeding to 
the northward and wintering to the southward. These 
facts are important to the student, as the number of birds 
to choose from varies with the season. For example, 
there are thirty-two sparrows and finches, of which 
1 is an all-the-year-round bird, 
12 are winter birds, spending the summer northward, 
2 are birds of passage, here only in the spring and 
fall, and 
17 are summer birds, spending the winter South. 
