INTRODUCTORY CHAPTERS.
felt, the second moulting occurs, and the feathers that have borne the wear and tear of winter give place to the fresh new coat, and the bird throat swells with the Spring Song.
From a residential standpoint, we have four distinct grades of birds to consider:—
| I. | The summer residents: Those birds which, coming to us in the spring, rear their young, and after shifting about somewhat in late summer, retreat more or less southward for the winter.
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| II. | The residents: Comprising those species which are represented by individuals all the year round.
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| III. | The winter residents: The birds who are inhabitants of boreal regions, breeding beyond the northern border of the United States, coming only to us in Winter, and retiring northward at the time of the general upward migration.
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| IV. | The migrants: Birds that are with us for a few weeks in spring, en route from the south to their more northern breeding haunts, and are also visible for a similar period during the return trip in autumn. We may class with these the casual visitors that appear for a brief visit either summer or winter.
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The two movements of bird life in spring and fall are known as the great migrations, some birds being plentiful in spring and quite rare in the autumn, and vice versa, as the path chosen for the upward and downward trip may not be the same. The individuals belonging to these classes will be specified in turn, and they are mentioned here to show you that if you do not begin the bird-quest in spring, in time to meet the army of migrants, you may miss some of the most interesting species.
Conspicuous among the birds that lodge with us in April and May, letting us hear their song for a brief period, is the great Fox Sparrow, the White-throated and White-crowned Sparrows, the group of lovely Warblers, and, best of all, the Hermit Thrush, whose heavenly notes of invocation, if once heard, are never forgotten.
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