The Migration of Birds 189 
about half-past ten. Almost as quickly, there was a 
decided increase in the number of call notes, and 
dozens of birds came within the range of the light, 
and several hovered about it, reminding one of large 
moths before a flower. When the rain finally ceased 
and the stars came out, the birds quickly ascended 
into the higher regions. Toward morning there 
seemed to be but a few stragglers, and before the sun 
rose the wave had passed. 
Frequently lighthouses are so situated that they 
afford excellent points for observation. Many times 
birds fly against them and are injured or killed during 
their night flights. It has been my experience to 
find more frequently the yellow- or black-billed cuckoo 
and vireos than other species killed by flying against 
the tower. This would lead me to believe that they 
do not fly so high as the others, or that they cannot 
see so well to avoid objects. This observation has 
extended over a period including twenty-four migra- 
tions. 
The speed at which birds migrate is a subject beset 
by many difficulties. There are several things to 
be taken into consideration; such as, whether it is 
the spring or fall migration, the first or the last part 
of it, the climatic conditions, and the accessibility of 
food. The average speed per day can be gotten at 
