36 Hoivell — Notes on Diurnal Migrations of Bats. 



during the early part of the summer indicated that those seen 

 in August and September were migrants. 



The observation which I have to record, though very unsatis- 

 factory in that the migrating species could not be identified, is 

 so unusual in several respects that an account of it is presented 

 in the hope that observations of a similar nature by others may 

 be brought to light. 



The morning of September 28, 1907, at Washington, D. C, 

 was cloudy and mild, with the wind light northeast. Rain began 

 to fall about 3 p. m. About 9 a. m. several bats were observed 

 flying at a considerable height over my house in the suburb of 

 Wood ridge, a short distance from the Boys' Reform School. 

 A few minutes later several more appeared, and the flight con- 

 tinued from 9 o'clock until about 10 o'clock, during which time 

 over a hundred bats were noted, all flying leisurely in one direc- 

 tion with the wind, i. e. southwest. A single individual was 

 seen at 10.45 a. m. They were not in flocks, but were flying 

 singly, usually only four or five being in sight at one time. The 

 manner of flight was quite unusual, for instead of the erratic- 

 zigzag flight commonly adopted by bats when seeking their fund 

 at dusk, the flight of those noted on this occasion was very 

 steady, consisting chiefly of a sailing or drifting motion with 

 occasional short flappings of the wings. Only a few of those 

 observed indulged in the characteristic bat flight and these for 

 only a few moments. The height of the bats above the ground 

 was estimated as varying between 150 and 400 feet — certainly 

 none were lower than 150 feet and a few were probably higher 

 than 400 feet. At this distance they looked so much like huge 

 butterflies that at first I could hardly believe they were bats, but 

 after observing them a few minutes through a field glass, it 

 became evident that they were indeed bats. At least three sizes 

 and probably three or more species were represented, but even 

 with the aid of the glass, no positive identifications could be 

 made. Most of them were about the size of the Red Bat and 

 very probably were either this species or the Silver-haired Bat. 

 A few appeared larger than these species, and a few were decidedly 

 smaller, belonging apparently either to the genera Myotis or Pi- 

 pidrellus, though neither of these genera is as yet known to 

 migrate, in North America. 



Inquiry has been made of a number of naturalists of wide 



