Page:Territory in Bird Life by Henry Eliot Howard (London, John Murray edition).djvu/246

Warblers, Whinchats, Stonechats, Meadow-Pipits, Tree-Pipits, and Skylarks. Suppose then that there had been sixteen pairs of Yellow Buntings instead of eight; that there had been other pairs, which assuredly there were, inhabiting the locality; that they had also resorted, which assuredly they did, to the coppice and arable ground for the purpose of securing food; and that their numbers had also been increased in a similar ratio—would a supply of food for all have been forthcoming with the necessary regularity and promptitude? Well, the parents might have had to travel a little farther; but even if they had been compelled to do so, their absence would only have been prolonged by so many minutes the more, and under normal conditions what harmful result to the offspring could possibly have followed? The question for us, however, is not what might have occurred under normal conditions, but whether the life behaviour is so adjusted as to meet the exigencies of diverse, and in this case of abnormal, circumstances. Now the capacity of the young to resist exposure diminishes very rapidly when the temperature falls below the normal—the danger zone seems to be reached at approximately 52° F., and the length of time during which they survive then becomes astonishingly short—and moreover the fall in the temperature would tend to decrease the supply of insect life upon which they depend, so that if the size of the territories had been reduced by one half, and the parents in consequence had been compelled to seek their