MIGRATION DATA ON CITY HALL TOWER. 1 7 



the tower. From first to last during the fall migration just passed, old 

 birds mingled with the young. The number of Maryland Yellow- 

 throats, for instance, which were killed right along from the beginning 

 to the end of the migrating season, August to November, contained 

 the saaie proportion of old birds. So it was with many other species^ 

 but there are many more young than old birds, of course. I thinlc the 

 reason that so few old birds strike the light in the fall is on account of 

 their experience. They have taken the journey between the north and 

 the south at least twice before, and they have become used to danger- 

 ous objects. In fact, they are experienced travelers, while the young 

 are not much more than children, and the new experience is bewilder- 

 ing, especially on a dark, cloudy night, when the birds Hy much closer 

 to the earth, and, child-like, they are fascinated by the light and want 

 to get right into it. Then they are possibly not so expert on the wing 

 as their parents, or they might be able to recover themselves at the last 

 moment when they have discovered their mistake. Thousands of birds 

 pass close to the lights, while but few strike, and it is reasonable to 

 suppose that the old birds are much more likely to escape than the 

 young. 



Threatening weather does not seem to prevent the birds from start- 

 ing on their migration, but a hard rain stops them. For example, one 

 night a large number of birds struck the tower when overtaken by a 

 northeast storm, but a hard northeast wind and rain continuing the 

 next day and night, not a bird struck, while from observations at another 

 point on this second night no birds seemed to be moving. 



On moonlight nights no birds strike, except toward morning after the 

 moon has disappeared. 



Another fact was noticed, that the birds not only migrate in the early 

 evening, but all night until break of day. At five o'clock one morning 

 the birds were going by in hundreds, while but few lost their lives. 



Following is a list of the species and the number of each which have 

 flown against the tower. A Sparrow Hawk on the list does not posi- 

 tively indicate that it was migrating at night, for it may have dashed 

 itself against some projecting corner while in pursuit of a wounded bird 

 in the early hours of the day. 



