Of course birds had made these stores; probably the jays and magpies, who yet retained an instinct which had become useless. With the equable climate and mild open winters of Central California, no bird need store up food; and this was shown by the great accumulations which had never been touched. Moreover, nuts were often put in holes that were inaccessible to so large a bird as a jay. So necessity has never corrected the failings of instinct by making a jay wonder, in the depths of winter, why he had been fool enough to drop his savings into a bank with the conscience of an ill-regulated automatic machine, which takes everything and gives nothing back. If he had really needed the almonds, they would have been put in an accessible spot. Though this perhaps is a scientific view, I must acknowledge that we were grateful to the birds who stored them for us, and, by making fools of themselves, gave us the opportunity of gathering, if not grapes from thistles, at least almonds from oaks.
Although I do not remember having seen any instances in California of the woodpecker which bores holes in trees and then neatly fits an acorn in, I have serious doubts as to the likelihood of the explanation commonly given. It is said the woodpeckers do it to encourage grubs--that they thus make a kind of grub farm. If so, why do they leave these acorns in? They do not perpetually renew them. Besides, there is no more need for them to trouble about the future than there is for the jays who made our almond stores. If I may venture to suggest an explanation--to make a guess, perhaps a wild one, at this acorn mystery--is it altogether impossible that the woodpeckers have imitated the jays? I have noticed that the jays get careless as to the size or accessibility of the hole they drop provisions into--indeed they will place them sometimes in little more than a rugosity or wrinkle of the bark. I have often found odd almonds on an oak tree which were only laid on the branch. The woodpeckers have probably mimicked the jays, and in so doing have naturally endeavoured to make the holes they had themselves drilled for other purposes serve them the same turn that the bigger holes did the jays. They have joined their work with play. It must be remembered that in a climate like California, where birds find it very easy to make a living all the year round, they are likely to have much time at their disposal, which would be occupied in a colder, less fruitful district. I should not be surprised to learn that there were many odd examples of useless instincts still surviving on the Pacific slope; for doubtless many of its birds found their way there from the east over the Rockies and Sierra Nevada.