Wednesday, 26 April 2017

Choughs dust bathing – or is it showering?

Most birders are familiar with bird dust bathing and this behaviour has been well recorded in many species in many locations across the world.  

The Google search for “bird dust bathing” gives web sites providing information and photos of dust bathing and some describe and show birds rolling or moving around in an area of dust which understandably looks like bathing as in bathing in water in a bath. The following description of this behaviour is from:

Dust bathing (also called sand bathing) is an animal behavior characterized by rolling or moving around in dust or sand, with the likely purpose of cleaning fur, feathers or skin, and removing parasites.[1] Dust bathing is a maintenance behavior performed by a wide range of mammalian and avian species. For some animals, dust baths are necessary to clean the feathers, skin, or fur, similar to bathing in water or wallowing in mud.[2] In some mammals, dust bathing may be a way of transmitting chemical signals (or pheromones) to the ground which marks an individual's territory.

The description of dust bathing from Wikipedia suggests the reasons for this behaviour are two-fold, that is feather cleaning and parasite control.

Sunning and anting are two other closely related behaviours and these are also thought to be for parasite control.

Recently I observed six White-winged Choughs (Corcorax melanorhamphos) applying a fine silty/clayey soil to their feathers, however in this case the birds were not bathing or rolling in the dust, they were applying the dust and soil with their bills, scooping up large bills full and inserting this deep within their back and breast feathers. As they did so, some of the liberally applied soil spilt over their outer feathers. I think this was accidental and the bird’s primary purpose was to apply the soil within the body feather layer, that is it was not intended as a surface treatment!

The soil was sourced from small holes excavated by the Choughs using their bills. I cannot say if the holes were excavated with the sole purpose of obtaining fine soil for their dust bathing or if initially they were dug in pursuit of insect food. In this instance the birds had a series of about five similar sized holes spread along a line about 2 metres long. The birds worked individually at the holes and then sometimes up to four birds would gather around one hole, all applying soil to their feathers – you could call it communal bathing I guess!

Three Choughs at one of the dust holes all working to apply dust using their bills.

Here the bird on the left is inserting soil with its bill into the back feathers while excess soil showers down the bird’s flank.
A second closer shot showing the same bird in the photo above.

 Judging by the brown eyes at least two of the six birds were immature.

This young bird shows how the body feathers were being fluffed up as part of the dust application process.
A red-eyed adult bird at one of the dust holes.
Four birds at one dust hole.
Adult bird at a dust hole.
Another bill full of soil being applied to feathers.
Same bird as a above working the soil into the back feathers.

I thought this observation of Choughs using their bills to apply to their feathers the dust and soil they have obtained from holes they have prepared, was worth reporting in a blog post. As to the purpose – feather cleaning or parasite control, or perhaps both – I am not able to say.

I had set out with my camera to see if I could find and photograph a couple of Scarlet Robins seen earlier in the day and while I managed to do this the unexpected discovery of the Choughs applying dust to their feathers was a real bonus. It just goes to show that when you head outdoors with the camera you never know what you are going to find. This for me is one of the great joys of birding and nature observation – expect the unexpected.

You know summer has passed and autumn is well underway when, following their summer breeding within the forest, Scarlet Robins come to the margins of the forest and to more open country and use farm fences as part of their “perch and pounce” hunting technique. A pair of Scarlet Robins working a fence line brings joy to a brisk autumn or winter morning.

Female Scarlet Robin
Male Scarlet Robin

Tuesday, 18 April 2017

Australian King-Parrot

King-Parrots (Alisterus scapularis) are common in East Gippsland and often visit our garden. Recently they have been feeding on the seeds of local Sweet Bursaria (Bursaria spinosa) and the fruits of non-local White Cedar trees (Melia azedarach).

Bursaria spinosa is of high value for wildlife as it provides habitat for birds and is a nectar source for butterflies and other insects. Further, as an understory bush it helps provide ecosystem stability in dry forest and woodland by hosting and sustaining wasps etc. that in turn keep in balance the insect larvae that skeletonise eucalypt leaves.

Melia azedarach, commonly known by many names, including White Cedar, is a deciduous tree in the mahogany family and is native to Indomalaya and Australasia. The fruits are poisonous to humans however the toxins are not harmful to birds. We planted some in our garden for their summer shade and fire resistance capacity. Being deciduous, frost is not an issue and they allow winter sun to penetrate.

In the wild King-Parrots are wary and fly a long distance if disturbed, however they can be very tame around parks and gardens. The ones in our garden are moderately confiding if approached quietly.

For the camera nerds - the following four photos were taken hand held using 600mm focal length in very low light at about 5.30pm with a fully overcast sky. I used ISO2000 and 1600 with f/5.6 aperture and 0ev giving shutter speeds of 1/40 to 1/160. You can achieve sharp images hand held with these settings when the subject is close.

Male King-Parrot feeding on Bursaria spinosa seeds. 

As the male fed he looked at me from time to time to make sure I was not a threat. 

A female King-Parrot was feeding close to two males.

The female also kept an eye on me as she fed.
The Bursaria seeds are soft, moist and green like a fresh pea – not dry and hard.

The following two photos were taken on another day of a male and female King-Parrot feeding on the fruits of one of the White Cedars.

Female King-Parrot feeding on the fruits of White Cedar.

They were eating the seed and discarding the outer fruity shell.

The male enjoying White Cedar seeds.

The King-Parrots have been attracted to our garden by planted local native shrubs and tropical trees native to northern Australia.

Notes regarding Australian parrots:

Note 1

I thought it was worth quoting the first two sentences of the Introduction to Australian Parrots (2nd Ed), Forshaw and Cooper, “Australia has been termed Terra Psittacorum – the Land of Parrots! Approximately one-sixth of the world’s species occur here and no other country has such a richness and diversity of forms”. How lucky we are!

The King-Parrot features on the back of the dust cover of the 2nd edition - illustrated with the late William Cooper’s magnificent paintings.

Note 2

Origin of the name King-Parrot

The species was originally called King’s Parrot for Governor Philip Gidley King. Later the ‘s was deleted from the name and later still RAOU introduced the hyphen, giving the current name King-Parrot (source - Australian Bird Names, Fraser and Gray).