238 The hish Naturalist. [October, 



equal duration. The evening flight is usually commenced a 

 little earlier than 15 minutes after sunset, the average of 

 seventeen actual emergences noted being 13 J minutes, the 

 earliest i minute, the latest 23 minutes, and the mean between 

 the extremes 12 minutes after sunset. The bat returns at 

 night to the same hole as serves it for sleeping apartment by 

 da)^ ; the precise time of its return, in the only instance noted, 

 having been 81 minutes after sunset. Its moment of leaving 

 the hole in the morning has also been noted only once, in the 

 case of the specimen caught on August 13th ; but it should be 

 remembered that this individual must have been the first to 

 emerge on the date in question, and therefore the usual time 

 of emergence is probably a little later than 86 minutes before 

 sunrise. The time of going home in the morning, on an 

 average of five observations, is 26 minutes before sunrise, the 

 earliest and latest instances having been 2>Z ^iid 21 minutes 

 before the sun. It has been shown that the duration of one 

 individual's (evening) flight was at least 71 minutes, whilst 

 that of another's (morning flight) was not more than 65 

 minutes. The usual duration is, in all probability, not far 

 from the mean between these two figures. The animal, there- 

 fore, in summer, spends one-tenth of its time on the wing, 

 and the remaining nine-tenths in its sleeping-hole. In the 

 shortness of its fiight-time it is probably unique among Irish 

 bats. 



Whether the same retreat is used in winter as during 

 summer I cannot say."" The field is frequented to a certain 

 extent from May to September ; but until midsummer, when 

 the cattle are pastured there, the bats fly in it for only a few 

 minutes each evening, just before retiring for the night. This 



^ I can uow (September 15th) answer this question with a qualified 

 negative, as the bats have lately desertecl the hole, and bestowed 

 themselves in separate crevices in the higher part of the tree. It is 

 noteworthy that they migrated singly, on different dates. On Sept. loth 

 three (instead of four) emerged from the common den ; on the nth, two ; 

 on the 13th, none. This shows that they changed their abode voluntarily ; 

 if they had been disturbed or alarmed they would all have left at once. 

 They still fly every evening from their new quarters. No two inhabit 

 the same hole. This apparent scattering for the winter — though it 

 might be thought a useful sanitary precaution before becoming torpid 

 and helpless — is the exact opposite to what has been reported of several 

 pther species, including F, noctula. 



