question about bird calls... are any identical? (1 Viewer)

there are so very many birds in the world. I am wondering if there are identical (not similar, and not imitating, as starlings might) calls in the bird world. I am accustomed to knowing basic calls but started thinking lately about how somewhere in the world there are two different kinds of birds who just happen to have identical calls.

catwhiskers63 said:

there are so very many birds in the world. I am wondering if there are identical (not similar, and not imitating, as starlings might) calls in the bird world. I am accustomed to knowing basic calls but started thinking lately about how somewhere in the world there are two different kinds of birds who just happen to have identical calls.

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Welcome to the forum. With parallel evolution I suppose that calls which sound the same can develop in different species. One that I often think of is the call of the Silvereye in Australia, which sounds very similar (call it the same, if you like) as the flight call of the Siskin here in Europe.

First time I heard a Mockingbird singing in the US, my immediate thought was 'How had it learnt to imitate a Song Thrush [from Europe] so perfectly?'

I don't think any species have identical calls, though to our ears they might. The process behind sound is so specifically evolved in each species that is unlikely to happen again. That is like suggesting the exact same species evolves a second time from independent evolution in a different environment.

I also suppose individuals in the species also differ, but again we perhaps cannot hear the difference.

Bird song is a pretty complicated behavior, with lots of constraints.

A song is first of all a result of a physiological process, requiring certain muscles etc. In that respect, I know of no reason why multiple birds (of similar size) couldn't produce identical sounds, and indeed we see that many birds are capable of mimicking other birds. (It's possible that what sounds like perfect mimicry to us in fact sounds terrible to the birds - but let's just assume that we're judging by human standards.)

A song is also a social phenomenon - it's not effective unless it's understood by other birds of the same species. This limits the speed at which new songs can develop, and it also means that two nearby species will usually need to find non-overlapping song styles so as not to waste each others' time.

Similarly, a song is a sonic phenomenon that occurs in a sonic "landscape" already crowded with sounds including other songs. To be heard at all, the song must avoid interference from other sounds or other songs. It's like radio signals: government regulators divide up the spectrum, and leave a bit of empty space between the stronger broadcast signals. But amateur operators all fit into a few small ranges, and avoid interfering by being physically dispersed compared to signal strength, and by simply taking turns - not trying to broadcast at the same times.

So there's a certain amount of audible "space" available which must be divided up between perhaps a few hundred songbird (and amphibian, and insect, etc) species in any one location. The question can be phrased thus: How many distinguishable ways can the sonic landscape be "sliced", and how does this compare to the number of songbird species * the number of spatially distinct habitats?

thank you so much for your responses. they are interesting and informative!

There is also the question of taxonomy - recently divergent species may not have evolved different vocalisations - I can think of several instances where I have had a strong response from one species using a recording of another (which of course may indicate that the species should not have been split in the first place!). An example is Tickell's / Austen's Brown Hornbills.

I think that there is some evidence that birds have "accents" in the same way as humans. i.e. a chaffinch in Germany sings the same song as a chaffinch in Spain but there are subtle differences as there are between Australian English and Canadian English.