LEISLER'S BAT -91 



while asleep In the sun at the edge of its abode. Mr Moffat 

 also informs me that he knew of one which slept in a hole in a 

 birch-tree, in a situation where the morning sun shone full on 

 its face. 



Although fond of congregating in colonies, solitary indi- 

 viduals are frequently to be found. Mr Moffat has met with 

 them from the middle of May to the end of September, and he 

 suggests that our information concerning the number leading 

 a gregarious life may be quite misleading, since it is the 

 largest and noisiest assemblages that are the most easily 

 discovered. 



This bat would appear to fly for a shorter period of 

 summer than any other known British species. In the 

 County Dublin it does not usually appear on the wing until 

 about 20th April, but by the end of that month it may 

 be seen in numbers, so that it is probable that the hardier 

 individuals may appear earlier in the month. It hibernates 

 early, retiring abruptly on or about 26th September, a date 

 arrived at independently by Dr Alcock at Dublin and by Mr 

 Moffat in Wexford. The abruptness of its disappearance is 

 remarkable; thus, in 1899, at Ballyhyland, County Wexford, 

 Mr Moffat m.ade the following observations, as quoted from his 

 journal: "September 25th, usual number flying; 26th, only 

 one; 27th, none"; the maximum temperature for the three 

 dates being respectively 57^^°, 53^ and 49" Fahrenheit. 



Although hibernation commences early, it is liable, as in 

 the case of the Noctule, to interruptions dependent on the state 

 of the weather. Mr Finn's specimen was taken on 21st 

 October, and had been flying with regularity for the previous 

 fortnight, sallying forth "every evening to the minute at the 

 same time." Mr Moffat has seen many on the wing in 

 Wicklow on 17th, and a single individual on 20th October, 

 and the late A. G. More identified one captured in a bedroom 

 on i6th November.^ Mr Moffat writes : "The lowest tempera- 

 ture at which I have noted Hairy-armed Bats in the open is 

 46 (on October 8th, 1899), but on that evening they were out 

 in some numbers. I therefore think that this species is more 

 influenced by the heat of the day than by that of the actual 



^ Moffat, Irish Naiuralisf, 1897, 135. 



