to reach the big carpenter ants (Camponotus herculeanus), which had extended their galleries up into the tree's heart, and some of which were already entrapped in the exuding pitch. Now one of the chief points of interest in this case was that the ant-borings were few, and the tree itself so large and solid that it would seem to be impossible for any bird to detect their presence by sounding with the bill. On the opposite side at the base, a long ant-hole was plainly seen, and at this point the observations of the woodpecker had evidently begun. A few feet above this opening it had attacked the harder wood in three different places, but desisted after making wells a few inches deep. The woodpecker then went up seven feet, where the wood was presumably softer, and made the drilling, which led to success. With these facts only known, this might appear like a case of reasoning by analogy, but there is still one sense unaccounted for, that of hearing, for the olfactory sense must be ruled out. It is possible, or even highly probable that such birds either instinctively or habitually follow the sounds in wood—sounds of wood-borers at work—and unless it could be shown that the boring of carpenter ants cannot be heard through five inches of solid wood, I should be inclined to accept this view.
This case suggests another practise of woodpeckers, the interpretation of which is clear. The president of a large university recently compared the futile efforts of certain reformers with these of a flicker which was seen to be repeatedly engaged in the vain attempt to "drill a hole through a copper gutter." The comparison may be apt to point a moral, but is a trifle unfair to both the instincts and intelligence of a useful bird, which will drum on any resonator, either to call its mates or for the pleasure of the sound, and by habit will come to the same place daily for more than a week, as in a case which we recently noticed. In this instance the resonant body was the roof of a bird house, one shingle thick, to pierce which, had that been its object, one or two blows of its strong bill would have sufficed.
II. Intelligence in Young Birds
The dawn of intelligence in young birds is seen, as we have earlier shown,[1] through the inhibition of the food-response by association—association with the parent, the nest or the vibration imparted to the tree by the touch of the parental foot.
For the first twenty-four hours, or longer, the altricious nestling behaves like a mechanical toy, and in relation to the food-response is a well-nigh perfect reaction-machine. It responds to every kind of a tactile or auditory stimulus, and within the limits of fatigue its
- ↑ See also "The Relation of Instinct to Intelligence in Birds," Science, N. S., Vol. XXVII., 1908.
