Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Thursday, April 20, 2006

The Choughs of the Botanic Gardens

Regular readers (and I do so hope you are all regular!) will realise that when in Canberra, I like to hang out at the Australian National Botanic Gardens (ANBG). I once was a Volunteer guide here, and those times were particularly happy for me. But when I left for Robertson I had to give up that service.

This autumn has been blessed with bluer than blue skies. There is not much else going on, in the world of birds, apart from lots and lots of White-winged Choughs (Corcorax melanorhamphos) scavenging for potato chips around Hudsons Cafe. And Crimson Rosellas, of course, but I shall leave them for another time.

These crazy Choughs look entirely black, until they spread their wings. When they are flying their two large wing patches are really obvious, and totally distinctive.

The other time they show their wing patches is when "displaying". Not only do they spread their wings wide, but they also do a weird thing with their eyes.

Their eye colour (the iris) is dark red as shown in Photo 3, (left). But they have pinkish skin around their eyes, and when displaying they somehow make their eyes bulge, and the skin around the eye gets enlarged, making the apparent eye size nearly treble the actual size of the eye. It is quite an effective display technique, even if it makes them appear stranger than normal to this human observer.

This behaviour is caught in one of my photos (below) but, as usual Geoffrey Dabb on the Canberra Ornithologists Group photo gallery has an excellent shot showing this display behaviour, complete with open beak, indicating the bird was clearly squarking, (as they do). My bird was stuffing its face, but still "displaying".

The Choughs of the Botanic Gardens have been particularly closely studied, possibly because their fondness for scraps of food from visitors to the Cafe makes them easy to observe. More likely it is because of their proximity to the Biology Department at the ANU.

In many respect they behave like "chooks", scratching around in the tan bark at the Gardens. But they are regarded as related to Crows and Ravens. They have many distinctive behavioural characterstics, such as "communal nesting", when 3 or more females lay eggs in the one nest, and a clan group collectively raise the young. The birds at the ANBG have been studied intensively, and many are banded with either colour bands, or, as in this photo, large numbered rings which are able to be read at a distance by field workers studying them.


x said...

I love your pictures!

Denis Wilson said...

Thank you X. And welcome to the world of blogging.