Whitakei- : N'otes on Bats. 75 



In support of my opinion that the winter colonies are usuallj^ 

 larger in buildings, and of both sexes, I may say that all the 

 usual arboreal quarters I know, which are made use of 

 in summer, are deserted during the winter months, and that a 

 colony apparently always occupies a certain church tower at 

 Worsborough Dale in winter, for great numbers of Noctules 

 may*be seen flying in its immediate vicinity in early spring and 

 late autumn, but not in summer. 



The colony of Hairy-armed Bats found at Oulton in a 

 cottage roof in late autumn of 1902, and the large colony 

 of Noctules occupying a house roof at King's I.ynn, Norfolk, for 

 many successive winters and springs, as recorded in a note by 

 Mr. H, B. Booth,* consisted of individuals of both sexes ' in 

 about equal proportions.' 



There is scope for much interesting speculation as to the 

 peculiarly erratic manner in which gregarious instincts are 

 displayed in our British bats. One cannot see that it is at all 

 necessary for their mutual protection, for they seem to have 

 hardly any enemies. Apparently it is not for warmth. On 

 cold, damp days, I have several times found Noctules occupy- 

 ing lonely quarters, whilst on September ist, 1906, one of the 

 hottest days I ever remember, Mr. Armitage and I examined a 

 colony of eleven Noctules in the hole of a tree in Stainbrough 

 Park, and found them packed in a solid cluster in one corner of 

 their den, actually wet with perspiration. The thermometer at 

 the time stood at 94° in the shade and 110° in the sun. 



I have found the Long-eared Bat {Plecotus auritus) scores of 

 times,' both in summer and winter, resting singly in cold, damp 

 chinks of tunnels and stonework, yet if the same species be 

 searched lor in August, usually the hottest month of the year, 

 small colonies of six to ten, or more, will be almost invariably 

 found squeezed together in one hole. August and early 

 September seem to be the only time when bats of this species 

 are gregarious. 



Of Natterer's Bat (M. nattereri).-, Daubenton's Bat {M. 

 dauhentoni). and the Whiskered Bat (M. mystacinns), I have 

 always found odd specimens, even in mid-winter, though large 

 colonies of each of these species hav^e been recorded. The 

 same thing applies to the Pipistrelle. I have found odd ones 

 even in winter, and on the other hand, I have found colonies 

 consisting of not merely scores, but hundreds of individuals. 

 * 'Zoologist' 1905, p. 427. 



1909 March i. 



