2i6 MAMMALS 



was over, for though the wind was still favourable 

 and many remained in the spider belt, these had 

 apparently used up all their energy and made no 

 further attempt to escape. 



About the migration of mammals I can only say, 

 from my own observation, that bats are strictly 

 migratory all over the pampas. Everywhere in that 

 flat country of some 60,000 square miles extent, bats 

 appear with the birds in spring, arriving later than 

 the early spring visitors, and vanishing with them 

 in March and April. Anyhow, I never found a hiber- 

 nating bat nor heard of one, although they were 

 abundant all the summer, hanging in the trees by 

 day, where in an hour or two I used to be able 

 to find and capture a dozen or twenty, just to 

 release them in a large room to observe them 

 in confinement. 



It is, however, my considered belief, which may 

 go for what it is worth, that the impulse and disquiet 

 is in mammals as well as in birds, fishes and insects, 

 albeit it does not lead to actual migration except in 

 some species and on rare occasions. 



I have long suspected that our common little shrew \ 

 is powerfully moved by the impulse at the end of 

 summer, as invariably from July onwards and through 

 the autumn months dead shrews are found lying on 

 roads and other open bare spaces; and this is not the 

 case only here in England, but all the world over 

 where the animal is found, in Europe, Asia, Africa 

 and America. It is possible that the little creatures 

 are subject to a mysterious malady which kills them 



