18 THE COMMON CROW. 



thing, is not too large an average — we should have 230,400 Crows in 

 the colony. 1 Because of the dim light at sunset, ray attempts at 

 taking instantaneous photographs of the incoming streams of Grows 

 were failures. A view, however, of one of the gathering nocks, taken 

 about an hour before sunset, as it flew by in a straggling stream, 

 shows 273 Crows in the photographic field. On this basis, the flying 

 time (an average of a number of observations) for the bird to cross 

 the field being fifteen seconds, in three streams coming in for one hour 

 we should have 199,560 Crows. But the streams toward the middle 

 and end of the incoming are manifestly much larger than the above, 

 so this number may be taken as a minimum estimate." 



At various times I have made careful estimates of the number of 

 Crows resorting to the roost in and near Arlington Cemetery, just 

 across the Potomac from Washington. On one occasion it was possi- 

 ble actually to count all the Crows which had settled on one stretch of 

 the sandy flats near the roost, and the number slightly exceeded 8,000. 

 A much larger number were perched in trees and scattered over the 

 surrounding fields, and large flocks were constantly arriving. Pres- 

 ently all or nearly all those on the flats took wing and joined the main 

 body, yet the addition of these 8,000 Crows did not appear to increase 

 the total number perceptibly. Subsequent examination of the woods 

 showed that the colony occupied 12 to 15 acres. Counting 10,000 to 

 the acre the total would be from 120,000 to 150,000 Crows. The most 

 conservative estimate of the number roosting at any one point in that 

 vicinity placed the number at 35,000.- Crows probably roost here and 

 there in favored spots over a tract of country 7 or 8 miles long and 

 perhaps a mile in breadth, but frequently the members of several of 

 these roosts may unite for one or more nights, and in very stormy 

 •weather concentrate at some one point. Thus in visiting the Arling- 

 ton roost at intervals of several days I was struck with the great 

 difference in the numbers at the roost on different nights. 



The following notes on Crow roosts illustrate the fact that these 

 winter colonies are always essentially alike. Mr. W. P. Hay, writing 

 the division under date of February 21, 1890, describes a roost near 

 Irvington, Ind., as follows : 



"For several years the Common Crow has been very abundant about 

 here, especially in winter. Every morning at about half past 5 a great 

 string of crows, extending as far as the eye can reach, can be seen 

 flying toward the south. At about 4 o'clock in the evening they 

 return. On the 15th of February I visited the roost, which is situated 



] It is difficult to realize the meaning of such a large number, and perhaps an 

 illustration may help. It happens that if one Crow came in each second, day and 

 night, it would require just sixty-four hours for this number to assemble. 



2 The number of Crows roosting in Arlington Cemetery during the winter of 

 1894-95 was very much reduced. 



