A Wave of Life. 67 
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 within two or three 
yards of the door-step, probably attracted by the 
smell of roasted meat. The weather continued dry 
until late in sprmg, so reducing the sheep and 
cattle that incredible numbers perished during a 
month of cold and rainy weather that followed the 
drought. 
How clearly we can see in all this that the ten- 
dency 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 inter- 
posed by predatory species were for a while in- 
appreciable. 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 war became apparent. In autumn the earth so 
teemed with them that one could scarcely walk 
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, 
F 2 
