34 



The Irish Naturalist. [ February, 



The cause of hibernation has been said to be due to the 

 cold, to a limited supply of air, to want of food, to an auto- 

 narcosis with carbonic acid, or to changes in the processes of 

 the cells of the brain ; the question is still undecided. 



Some hibernating animals, such as the Squirrel, lay up a 

 store of nuts and other edible substances for the winter, which 

 they consume at intervals. Many bats, though they store 

 their food internally, wake up occasionally and eat whatever 

 is to be found. Kinahan noticed this in the case of the 

 Lesser Horseshoe Bat ; I have seen it also in the Whiskered 

 and IyOng-eared species; these, however, were in captivity. 

 The sexes would appear to hibernate apart. 



A certain amount of evidence has been adduced to prove 

 the migration of bats. Kinahan (xii.) showed in the case of 

 the Lesser Horseshoe Bat that the caves in which it passed 

 the winter were deserted in the summer, and Mr. G. Dowker 

 (v.) observed that the Noctule which inhabited his roof during 

 the winter flew elsewhere in the months of July and August 



Dr. C. H. Merriam (xiii.) claims migratory habits for 

 Atalaphe cinerea and Vesperugo ?ioelivagans. Mr. R. M. 

 Barrington (quoted by H. I,. Jameson, x.) finds that some 

 species — amongst them the Pipistrelle — occur at lightships 

 on the Irish coast. Mr. S. Grieve (vii.) suggests that 

 Daubenton's Bat is migratory in Scotland. Other more 

 ancient authorities are quoted by Mr. J. E. Harting (viii.). 

 While fully recognizing the value of the evidence thus 

 brought forward— which indeed my own observations support, 

 as far as they extend— more light on the subject is very 

 necessary, and it would be interesting to learn how far a bat 

 travels when it shifts its quarters, and where it goes to ; it 

 might be that its habits were rather " nomadic " than 

 migratory in the strict sense of the word. 



The food of our native bats has been the subject of many 

 curious fables, some of which have been collected by Mr. E. 

 Newman in the Field for 1874. It would seem that all are 

 insectivorous when in a wild state, apparently exclusively so. 

 Various species of insects are laid under contribution, and 

 bats have repeatedly been seen feeding on the wing, close to 

 the observer. In some cases the actual species is recorded : 

 thus the Noctule is said to specially prefer the little hairy 



