10 THE COMMON CROW. 



for long periods at a time, and where a fair amount of animal food is 

 assured. While such conditions usually exist almost anywhere south 

 of latitude 40°, the seashore and the banks of large rivers afford the 

 best chances of obtaining a constant supply. Hence it seems probable 

 that the great majority of Crows reared in the Northern States do not 

 pass south of latitude 35°, but are concentrated at certain places, deter- 

 mined by the food supply, in the belt between the thirty-fifth and for- 

 tieth parallels. The great center of Crow population in the eastern 

 part of this winter zone is in the neighborhood of Chesapeake Bay and 

 its tributaries 3 a more western center is found near the junction of the 

 Ohio and Mississippi rivers, while large numbers winter farther west, 

 along the Arkansas and lower Missouri. 



As usual with migratory birds, the northward or spring movement 

 is more plainly marked, or at least more conspicuous, than the south- 

 ward or autumn movement. In southern New York and Connecticut 

 the spring migration often begins early in February, and by the latter 

 part of that month or the 1st of March Crows in straggling flocks or 

 singly appear in abundance all over New England and the Middle 

 States. Occasionally the first arrivals come in flocks of many thou- 

 sands, scattering to some extent to feed during the day, but collecting 

 together to roost. More often the first migrants come in parties of a 

 dozen or two individuals flying so far apart as to give the impression 

 that each Crow is moving independently. In leaving winter quarters 

 to move north in spring they depart in large flocks, and the same is 

 probably true of the initial southward movements in the fall. These 

 large flocks rarely if ever complete the journey with unbroken ranks, 

 but divide and subdivide until in many cases the members arrive at 

 theii destination in small parties or even singly. Toward the close of 

 each day's flight, however, single migrants show a decided tendency to 

 unite with other stragglers, and these combined companies often reach 

 some local Crow roost, where they pass the night with the Crows of the 

 vicinity, or perhaps at a late hour rejoin the flock with which they 

 started at daylight. Crows often fly until long after dark when they 

 have a definite roosting place in view, but their migrations are per- 

 formed mainly by day. 



In the Middle and Southern States March and October are unques- 

 tionably the greater migration months for Crows, and under average 

 circumstances the greater part of the movement takes place during 

 the first half of March and the last half of October. This is shown by 

 careful study of the dates of appearance at successive points in spring 

 and fall and the increase or decrease at particular roosts. 



CROW ROOSTS. 



Crows are notoriously clannish birds, and except during a few weeks 

 at nesting time are usually seen in flocks. Moreover, even while nest- 

 ing they are more or less gregarious, for although two nests are seldom 



