THE PASSING OF THE BIRDS. 185 
birds. They flew directly south, at a mod- 
erate height, and were almost certainly de- 
tachments of one body. The bluebird move- 
ment was two days later, at about the same 
hour, the morning being cold, with a little 
snow falling. This time, too, as it happened, 
the flock was in four detachments.* Three 
of these were too compact to be counted as 
they passed; the fourth and largest one was 
in looser order and contained a little more 
than a hundred individuals. In all, as well 
as I could guess, there might have been about 
three hundred birds. They kept a straight 
course southward, flying high, and with the 
usual calls, which, in autumn at least, al- 
ways have to my ears a sound of farewell. 
Was it a mere coincidence that these swal- 
lows, bluebirds, and robins were all crossing 
the valley just at this point? 
This question, too, I count it safer to ask 
than to answer, but all observers, I am sure, 
must have remarked so much as this, — that 
birds, even on their migrations, are subject 
to strong local preferences. An ornitholo- 
gist of the highest repute assures me that 
his own experience has convinced him so 
strongly of this fact that if he shoots a rare 
