THE ANNUAL MEETING. 11? 



turmoil of business. A part of these, though loving association with man, are 

 more rustic in their tastes, preferring the quiet life of the farm, where they 

 nest about the buildings and under the brown eaves of the barn or in the 

 scattered shade trees of the fields. And these differences in bird likings are 

 not mere vulgar matters, depending upon food or proper nesting places, but 

 seem to be of deeper significance, and are perhaps akin to human likes and dis- 

 likes. It is from these man-loving birds that our help must come, and a study 

 of the the habits of intimacy or estrangement of the various species cannot 

 but be of great value. 



But these questions must be left with this hurried glance, while we take up 

 the subject of the length of time which the various species remain with us, and 

 incidentally, why they leave us and where they go. 



My study of Michigan birds has been of those of the southern and central 

 parts of the lower peninsula, but the inferences drawn will apply, with but 

 little change, for all of the State below the Straits of Mackinaw. 



Migration is a term applied to regular periodic changes of location in ani- 

 mals; this movement being only found, to any extent, in birds and fishes. In 

 birds it exists only in those occupying temperate and cold climates; those of 

 tropical countries being nearly or quite stationary. The migratory instinct is 

 also found most perfectly developed in those birds whose foods are produced 

 only during warm weather. The vireos and warblers, whose food is chiefly 

 soft insect larves which feed on green foliage, move to the south with the 

 first frosts. The robins that feed, to quite an extent, on fruits and earth- 

 worms, do not move southward until the ground freezes or is covered with 

 snow. It is not then so much cold, as the lack of suitable food, which causes 

 the migration of birds. They can become fitted for changes of weather by 

 warmer coats of feathers, but the nature of their food is of deeper significance. 



We could perhaps, better understand some of the phenomena of migration if 

 we could imagine a giant sower gathering the birds together from the north 

 country in the fall and throwing them at one mighty cast to the south, and 

 then in the spring throwing them back to the north. But to represent the 

 migration of such birds as our robin, he would have to stand in southern Ohio 

 and the casts to the north and south would overlap at his feet ; while to repre- 

 sent the migrations of the warblers, he would have to stand away to the north 

 of Lake Superior and throw them clear over the United States into Mexico and 

 Central America. 



But a better idea of migration would probably be gained if one could think 

 of the individual birds of any one species as fixed in a movable frame, which 

 should move back and forth spring and autumn. It is probable that where a 

 migratory species is called resident, the birds found during the winter are those 

 which have nested far to the north, and not those which nested in the locality 

 itself; the birds thus keeping something like the same relative position to 

 each other both in their nesting and wintering habitats. It seems probable 

 that no two species of birds have exactly the same habitat, their migrations 

 differing in extent north or south, or their habitats differing in breadth east 

 and west. 



The birds of Oregon and the west coast usually follow their own line of 

 migration to the west of the Rocky Mountains, as far at least as Mexico. 



All the birds of North America which enter South America in their migra- 

 tions, probably do so by way of the Isthmus of Panama, and return by the 

 same way, the various allied species separating on their return to the north and 

 each going to its own place. 



