Mystery bird call
A little while back, I was visiting my parents in Rosanna (a suburb in Melbourne only a few kilometres from my place). it was a pleasant morning, and we were on the veranda at the back of their house.
At some stage in the conversation, a bird began calling. I pricked up my ears, trying to identify the bird. As so often happens, it sounded familiar, but I couldn't quite put my finger on it.
Describing a bird call is a very difficult task. If pushed, I try to find a word that conveys the same sort of general sound as the call. In this case, my guess would be the word "woody", although with the emphasis on the second syllable rather than the first.
It was repeated in groups of between three and seven, with a short gap between each group.
Yeah, I know, not very communicative.
My curiosity piqued, I pulled my phone out of my pocket and made a recording of the call. It wasn't a particularly good recording, but there's enough bird and sufficiently low background sound to allow me to make a sonogram.
I've talked about sonograms before. It's a graphic representation of sound, showing different pitches (measured in kilohertz) against time. You can think of it as a very detailed pianola roll.
I used Raven Lite (a free program distributed by Cornell University) to convert the recording from my phone to graphic form. It wasn't difficult, although I had to use a different program to convert the "m4a" type recording my phone gave me to a "wav" recording that Raven was expecting.
Looking at the sonogram, it's clear that the call is a repeated pair of syllables, a short tone (at about 2.8kHz) followed by a higher one (at about 3.8kHz). The call repeats about four times per second with about a half second gap between groups.
There is also a clear set of harmonics, which gives the call a pure tone. Too many harmonics tends to give the call a harsh buzzy or rattly quality.
Have a look at the sonogram.
I posted the sonogram and a soundtrack on the Birding-Aus Facebook page. After only a few minutes, opinions from experts started coming in. The consensus is that the bird is the very common Noisy Miner. It's not a normal call, though, and a few contributors suggested that it's a juvenile.
The Noisy Miners around our place have a slightly different call. It's more of an upward whistle, displaying none of the two-step pitch that is revealed in the sonogram.
If this is the case, it shows that even birds have local accents or dialects, and they can be significantly different, even a few kilometres apart.