The Influence of Weather on the Generation of Outbreaks

Abstract

If the proximate cause of the beginning and end of outbreaks of animals is an increase and subsequent decrease in the supply of their food, what then drives these changes in the availability of the food? That there is synchrony of peaks in abundance over wide areas — not only of the one species, but of often quite dissimilar ones — suggests that a common extrinsic agent is responsible. That the same animals which reach outbreak numbers in harsh environments do not do so in gentler ones suggests that in these latter places the causative agent is either not operating or is much less variable in its action. The evidence from outbreaks which are not cyclic suggests that there are still other places where it acts only spasmodically.