17 Sep 2016

Dianne Brunton: bird songs and dialects

From Saturday Morning, 10:10 am on 17 September 2016
Dianne Brunton

Dianne Brunton. Photo: supplied

Kim Hill talks to Professor Dianne Brunton, who founded the Ecology and Conservation Group at the Albany campus of Massey University, and currently heads the Institute of Natural and Mathematical Sciences.

She specialises in the study of New Zealand's native birds, and their communication through birdsong. Backed by the Marsden Fund in 2013, her team are tracking the dialects of songbirds in Auckland and Northland.

Read an edited excerpt of the interview below:

You’ve been studying this for a long time, and I’ve heard you talk about how tuis differ, how saddleback dialects differ, and similarly with bellbirds, yes?

I’ve been interested in bellbirds for a while. Years ago when I came back from doing a PhD and post-doc in the US, I was really struck by the fact that bellbird females sing. That northern hemisphere bias in birdsong research, focusses on male song because the females don’t sing much. In New Zealand and Australia, in the tropics, it’s really striking how males and females sing, so we started working a little bit on bellbirds and then we switched to saddlebacks for a while, then I came back to bellbirds when I got the Marsden grant in 2013. That’s really to focus on male and female dialects. They have different dialects and the use of the song and the relationships that males and females have in using the song are quite different.

How many different songs would they have? For example a mating song, and a “hello is anybody out there?” song…

It’s not quite like that. What we have found is that the songs, they have lots of different song types, they put the syllables together in different ways, there is an overlap in the syllables that we see. There is a whole language that goes along with studying song. But those are the components that make up the different little parts of the song that make up the overall bout of a song.

In bellbirds, males and females sing songs that are probably three seconds long, but they put them together in lots of different ways. The syllables males have and females have are about… three-quarters of them are different, there is a little bit of overlap and so we’ve been looking at that in terms of lots of island locations.

There are three projects that centre on the bellbird song. One is the development of the song and my PhD student has been tracking chicks from the nest until they set up territories and looking at how the songs of males and females develop over that time. They start out, there is this baby babble where you can’t even work out what the syllable is, and they finally crystalise when they are about a year old. We wanted to see if males and females have the same development of song.

Do they?

They do, which suggests they have similar structures in the brain and similar structures in the syrinx.

Hang on a minute, I was astonished about this, you say in the northern hemisphere, in general, only the male birds sing?

Yes. The females might give little calls, but the males are the ones that set up territories and display to attract females and to keep other males out.

I never knew that. So, do you think if you examined the brains of the northern hemisphere birds, would their brains be different?

Well, yes and no. the birds that sing, whether they are male and female… especially the song-learning birds, so the birds that have to acquire their song from tutors that are either their parents or other birds they hear in their environment, so those birds have got certain structures in the brain that enable them to learn and then enable them to crystalise that song and produce it.

Females in the northern hemisphere start out with the same structures in the brain, but then the females, by the time they are one year of age, have lost that ability to learn song and produce it. We haven’t looked at the brains of bellbirds yet, this is an endemic, native species that is protected, so we are able to collect specimens that have died of natural causes, but we plan on looking at the structure of the female brain as well.