Sense of Hearing in Insects and Birds. “Towering” of Birds

Abstract

I AM glad to learn from Mr. M'Lachlan that stridulation is known to occur in several species of Lepidoptera; for this shows that the sense of hearing in these insects is probably of general occurrence. With regard to the sense of hearing in birds, I did not say in my previous letter that thrushes, &c., were guided to their food exclusively by this sense; indeed it would be a very anomalous thing if animals which possess so keen a sense of sight are not in the habit of using it, as Mr. McLachlan suggests, in any profitable way they can. But that thrushes trust very largely to their sense of hearing in their search for food—especially in certain conditions of the ground—no one, I think, who has observed the process can doubt. The bird runs rapidly some twelve to twenty feet in a straight line; it then stops. suddenly, elevates its head, and remains motionless in a listening attitude; after pausing thus for a few seconds, it again runs to about the same distance as before, again stops to listen, and so on. These successive excursions are usually made in the same direction; but every now and then, during the process of listening, the thrush apparently hears a sound proceeding from some point within the circle which it has last entered; immediately the course of progression is deflected at an angle from the continuous straight line in which ail the previous excursions were made, and, either with a single rush or after one or two brief pauses to make quite sure of the exact spot, the bird may nearly always be seen to find a worm.