1905 Moffat. — Duration of Flight Mnong Bats. 99 



to suppose that it is nocturnal," and so he thinks that it " only 

 flies late in the evening." Thus the acknowledged fact of 

 nothing being known about it is made a ground for placing 

 it in the crepuscular rather than the nocturnal class. The 

 adoption by a leading naturalist of so singular a line of 

 argument shows how fashionable the belief has become — in 

 consequence, no doubt, of Dr. Dobson's dictum — that evening 

 flight is the rule among British Bats, and all-night flight the 

 exception. 



Well, with Dr. Alcock's help, I made some observations on 

 these subjects, extending over several summers, which resulted 

 in our ascertaining the truth about four species of Irish Bats, 

 of which there are altogether seven. The four whose flight- 

 times we succeeded in ascertaining are the L,ong-eared Bat 

 the Hairy-armed Bat, the Common Bat or Pipistrelle, and 

 Daubenton's Bat. As regards the first two, the results have 

 already been published,^ but T may repeat here that the Long- 

 eared Bat was shown to fly all night, and the Hairy-armed 

 Bat to conduct itself in a very difi'erent manner. That 

 creature flies only in the two twilights, morning and evening, 

 each time for about an hour or an hour and a quarter, and 

 passes the rest of the night — that is to say, far the greater 

 part of the night — in the same sleeping-hole in which it 

 spends the day. So the Hairy-armed Bat's idea of the 

 quantity of sleep it requires on a summer's day is 21 J hours, 

 while in winter it takes an almost uninterrupted rest for 

 six months. Of course, these facts were only ascertained 

 gradually. We were first led to suspect them — or rather, Dr. 

 Alcock was led to suspect the early retirement— because this 

 big Bat used to disappear from view before the little Bats did, 

 which is the opposite of what ought to happen if they all 

 flew equally late. Then Dr. Alcock shot some specimens 

 which could not have been flying more than an hour, and 

 really the creatures were so monstrously full — so round and 

 firm and hard (almost like cricket-balls) — with the quantity 

 of insect food they had gorged in that short interval, that it 

 seemed to both of us utterly impossible that they could w^ant 

 to feed any longer. In the end, having discovered that they 



1 Irish Naturalist^ vols, ix., pp. 235-40, aud x., pp. 241-51. 



A 2 



