Manchester Memoirs, Vol. liv. (1910), No. 10. 



X. A Hypothesis as to the cause of the Autumnal 

 Epidemic of the Common and the Lesser 

 Shrew, with some Notes on their Habits. 



By Lionel E. Adams, B.A. 



Received January 2Sih, igio. Read February 8th, igio. 



The " autumnal epidemic " of the shrews has been a 

 standing puzzle to naturalists for a long time. It does 

 not seem to be generally known that, though the autumn 

 is the time when these little creatures are found dead in 

 the greatest numbers, their corpses may be found at any 

 season of the year. During the winter months they die 

 from hunger, cold, or attacks of enemies ; in spring sexual 

 conflicts lead to many deaths ; in summer drought is 

 often, I believe, the cause of much mortality, and also at 

 this season many inexperienced young die from various 

 causes. At the end of July, 1906, I found many dead 

 on the roads, and I supposed that a prolonged drought 

 accounted for the mortality. At this time the Shrews, 

 Bank Voles, and Long-tailed Field Mice all seemed to 

 have deserted a certain locality, near Reigate, where they 

 were usually plentiful. During this period there was 

 very little dew at night, and I think the little animals left 

 the place in search of water. Mr. J. G. Millais with 

 reference to this point says : * " Scarcity of food may 

 account for it, but not drought, for in places where Lesser 

 Shrews are abundant I have found many dead, while 

 pools of water lay around in every direction." This 

 instance, however, merely tends to show that these par- 

 ticular individuals died from some other cause, not that 

 • " Mammals of Great Britain and Ireland," vol. i., p. 147. 



March 31st, igio. 



