154 THE ZOOLOGIST. 



turned to dust, and with the disappearance of their food and 

 cover the mice had ceased to be. The famine -stricken cats 

 sneaked back to the house. It was pitiful to see the little 

 burrowing Owls ; for these birds, not having the powerful wings 

 and prescient instincts of the vagrant Otus braclii/otus, are 

 compelled to face the poverty from which the others escape. 

 Just as abundance had before made the domestic cats wild, 

 scarcity now made the Burrowing Owls tame and fearless of 

 man. They were so reduced as scarcely to be able to fly, and 

 hung about the houses all day long on the look-out for some 

 stray morsel of food. I have frequently seen one alight and 

 advance to within two or tbree yards of the door-step, probably 

 attracted by the smell of roasted meat. The weather continued 

 dry until late in spring, so reducing the sheep and cattle that 

 incredible numbers perished during a month of cold aud rainy 

 weather that followed the drought. 



How clearly we can see in all this that the tendency to 

 multiply rapidly, so advantageous in normal seasons, becomes 

 almost fatal to a species in seasons of exceptional abundance. 

 Cover and food without limit enabled the mice to increase at 

 such an amazing rate that the lesser checks interposed by pre- 

 datory species were for a while inappreciable. But as the mice 

 increased, so did their enemies. Insectivorous and other species 

 acquired the habits of Owls and Weasels, preying exclusively on 

 them; while to this innumerable army of residents was shortly 

 added multitudes of wandering birds coming from distant regions. 

 No sooner had the herbage perished, depriving the little victims 

 of cover and food, than the effects of the w r ar became apparent. 

 In autumn the earth so teemed with them that one could scarcely 

 w r alk anywhere without treading on mice; while out of every 

 hollow weed-stalk lying on the ground dozens could be shaken ; 

 but so rapidly had they been devoured by the trained army of 

 persecutors, that in spring it was hard to find a survivor, even 

 in the barns and houses. The fact that species tend to increase in a 

 geometrical ratio makes these great and sudden changes frequent 

 in many regions of the earth ; but it is not often they present them- 

 selves so vividly as in the foregoing instance, for here we see count- 

 less myriads of highly organised beings rising into existence only 

 to perish almost immediately, scarcely a hard-pressed remnant 

 remaining after the great reaction to continue the species. 



