Why Bird Songs Sound Musical To Us

26 July, 2006
If bird "songs" are not bird music, then why do they sound musical to us?

Animal Music

In my article Animal Music, I asked if animals make music like we do, and I answered mostly in the negative, that even if there was such a thing as animal music, analogous to human music, animals themselves wouldn't be clever enough to make it up.

But I failed to answer a related question, which is why do many animal calls and "songs" sound musical to us?

Why Birds Sing

I recently finished reading "Why Birds Sing: a journey into the mystery of bird song" by David Rothenberg. Rothenberg is fascinated by the relationship between bird song and human music. The book starts with him jamming with birds in the National Aviary in Pittsburgh, USA, and it ends with him jamming with an Albert's lyrebird in Lamington Nation Park in Queensland, Australia.

As Rothenberg tells us, bird song has its own music-like regularities and rules, in fact the song of each bird species has its own unique regularities and rules, which are different to the regularities and rules of human music, yet similar enough that there can be interaction between bird and human. Some birds introduce the sounds of human music into their repertoire, which in some cases survives multiple generations, and many human composers have been inspired by the songs of particular birds.

So if bird songs aren't music, how come they sound so much like they are music?

The Super-Stimulus

It has been argued that human music is somehow a result of sexual selection. One argument for this comes from analogy with bird song. Many bird songs are sung by males to attract females, and sexual displays are subject to the phenomenon of sexual selection, first identified by Darwin, and analysed in more detail by the famous evolutionary biologist Ronald Fisher. Fisher identified the concept of "runaway" sexual selection, which can be described as a sexual stimulus becoming a super-stimulus for itself.

This is similar to my theory of music, which suggests that music is a super-stimulus for the perception of musicality, but an important difference is that music is not a super-stimulus for itself, because it is a super-stimulus for the perception of the musicality of speech.

Sexual selection is not the only explanation of bird songs involving super-stimuli. In his book, Rothenberg describes the ranging hypothesis: bird songs sound clearer when they are closer, and in order to aggressively claim territory, birds will want to sing their songs as clearly as possible, to always make themselves seem closer to a potential competitor or trespasser than they really are. Thus the singing evolves greater and greater clarity, and any bird that sings less clearly than other birds of the same species will fail to stake out a full-sized territory.

An Aside: Some Reasons Why Sexual Selection Doesn't Work as an Explanation of Human Music

Similarities Between Different Super-Stimuli

So if music is one kind of super-stimulus, and bird song is another kind of super-stimulus, how come they often sound similar?

A plausible answer is that super-stimuli are (by definition) extreme versions of normal stimuli, and there are only so many ways of being extreme. As a result, certain characteristics will turn up again and again in different super-stimuli.

To give a simple example, male bird colourings are typically determined by sexual selection, and very often these are bright colours. The peacock is famous for its (sexually selected) long tail, but also for the very bright blue of its neck feathers. The blueness of the peacock is a super-stimulus for the peahen's perception of peacock blueness. It just so happens that we also find the peacock's blue colour "beautiful", even though it does not stir any romantic tendencies in us (at least not towards the peacock).

Something similar can happen with bird songs. If human music is a super-stimulus, then it is a multi-aspectual super-stimulus, because, as explained in my theory, musicality consists of multiple aspects of musicality corresponding to multiple aspects of the perception of speech melody and rhythm. If different kinds of bird songs are super-stimuli for different aspects of perception of those same bird songs, then there will be many cases where the relevant aspects partially match at least one corresponding aspect of the human perception of musicality. As a result, we will consider many of those bird songs to be at least partially musical, even if it is never "music" that is musical enough to get into "Top of the Pops".

A Shared Sense of Beauty

Like many other students of bird song, Rothenberg wants to believe that birds have some sense of "beauty" which underlies their singing efforts. If we allow that "beauty" is another word for "super-stimulus", whether we are talking about the beauty of a beautiful woman, or the beauty of a mountain view, or the beauty of a piece of music, then we can say that the birds do have their own sense of beauty, which is not always the same as ours, but which sometimes intersects sufficiently to create a meaningful interaction across the species divide.