Tuesday, 28 January 2014

More on aging and sexing Rufous Whistlers

Following some interesting feedback on the previous piece on aging and sexing Rufous Whistlers Pachycephala rufiventris, I have added a few more examples of details to look for when doing so.

Adult female Rufous Whistler
Charcoal Tank, NSW, Oct 2010
This first adult female (3+) shows the features of a dark red eye, dark black bill, white throat streaked with dark grey and streaked breast.

Left - Adult female, right Immature (unsexed)
Charcoal tank, NSW, Oct 2010
The shot above shows a second adult female (3+) alongside an immature, unsexed bird (2). Her eye is clearly red compared with the young bird's brown eyes. Her head is grey streaked with black, her belly is pale buff, almost white, and she has very little streaking on her undertail coverts. In comparison, the young bird has a grey/buff head with finer black streaks, its belly is a creamy orange and there is definite streaking on the undertail coverts. The immature bird would have hatched in the Spring two years previous to that when the shot was taken, but as it was still early in the breeding season when the bird was caught, October, and as sub-adult males can breed in their second year while in such a plumage, the bird cannot be sexed. It might yet moult into sub-adult male plumage later in or after the breeding period.

The photograph below shows the heads in profile of the same two birds. Note the female's grey head versus the young bird's brownish colour. Her iris is red, the other bird's is brown. Her bill is black on the outside upper and lower mandibles, and inside. The young bird's bill is dark, almost black on the upper mandible, brownish grey on the lower, and with a pale yellow inside the roof. Also her bill is worn with use, with chips and flecks taken out of it, while the young bird's bill is smooth edged and clean-looking with pale margins.

Left - Adult female, right Immature (unsexed)
Charcoal Tank, Oct 2010
In comparison of the two adult birds, the second adult female has a brighter shade of red in her eye, her breast is less rufous, her belly is paler, and her undertail coverts are less streaked. This might simply be normal variation in colouring between individual birds. However, she might be an older bird, so further study needs to be done on the features listed here on re trapped birds of known age, to help clarify this point.

Sunday, 26 January 2014

How to age and sex Rufous Whistlers

Two Rufous Whistlers - but what age and sex are they?
Charcoal Tank, NSW. March 2010
I have recently been in correspondence discussing how to age and sex Rufous Whistlers Pachycephala rufiventris, so considering that they are one of the most widespread bird species in Australia, I thought I should post a simple guide to this dilemma. 

The problem arises from their plumage moult sequence over the first years of their life. For they take three years to attain full adult plumage, and during the first two years, the males and females are alike (to our eyes and criteria so far discerned). Do the birds know which sex each other is, I'm sure they do, so why can't we tell?

This is not a complete description, indeed there might be errors. However, during future banding trips, I hope to photograph birds of known age (from previously banded birds) and note details which will help to further understand how to age and sex these common birds. The page will then be updated as fits new points to consider.  

Juvenile Rufous Whistler
Charcoal Tank, NSW. January 2011

Juvenile (J) Rufous Whistlers are recognisable by their bright yellow gape, the skin at the base of their bill, light-coloured bill and heavily streaked breast. These are usually being closely attended by adult birds.

Eye - dark brown iris

Bill - pale grey upper mandible, pink/yellow/grey lower  
         mandible, orange yellow inside

Breast - buff and heavily streaked

Throat - grey streaked with dark grey

First-year or Immature  Rufous Whistler
Charcoal tank, NSW. Sept 2012

First-year (1 or 2-) birds, or immature, those in the first year of their life have a similar plumage to the juveniles and adult females. Also the sexes are indistinguishable. The orange/yellow inside of the bill is the most diagnostic feature when in the hand, but not so useful in the field. Then, the pale lower mandible below the darker, but not dark black bill is the best feature to look for.

Eye - brown

Bill - dark grey on top mandible, pink/brown lower mandible.

Breast - pale buff streaked with dark grey.

Throat - grey streaked with dark grey/black.

Adult female Rufous Whistler (3+)
Charcoal tank, NSW. Nov. 2012

Adult female (3 or 3+) birds can be recognised by their black bill, dark red iris and lightly streaked breast. Their throat is white rather than grey as in a first-year bird. However, second-year males (2), i.e. those more than one year since hatching, look very similar. Banded birds can be aged with reference to when previously caught, otherwise behaviour is perhaps the only clue to sex in the field. In spring and summer try to determine whether the bird is behaving like a male or female. And beware of this piece of confusing knowledge - male Rufous Whistlers (and females?) can breed in their second year while in sub-adult plumage or in that similar to females.

Eye - dark deep red

Bill - black top, lower, and inside, pale palate

Breast - light rufous streaked with dark grey

Throat - white, streaked with dark grey

Sub-adult male Rufous Whistler
Charcoal tank, NSW. Sept 2012

Second-year, or sub-adult male (2) i.e. those more than two years since hatching, but less than three. These birds show the beginnings of adult male plumage coming through the immature plumage which was similar to that of a female. A dark grey or black breast band spreads across the top of the breast, and black feathers come in around the face. The throat whitens and loses its streaks. And the iris is red, but not as bright as that in an adult male's eye.

Eye - dull red

Bill - black on top, lower and inside, pale palate

Breast - rich rufous, with narrow dark streaks, faint or
             incomplete breast band

Throat - white and lightly streaked, dark feathers
              around face

Adult male Rufous whistler
Charcoal tank, NSW. Sept 2012 

Adult male (3 or 3+) Rufous Whistlers are the easiest to identify, not only to species but to sex. They have a distinctive rufous breast, belly and undertail coverts, a bright white throat and a black breast-band with linked black feathering up the sides of the throat and across the face. The eye is bright red and the bill glossy black.

Eye - rich red iris

Bill - black top, lower and inside

Breast - rich rufous with a black breast-band

Throat - pure white

Saturday, 25 January 2014

New Travel Blog

The Lion of St Mark and St Theodore atop columns  in Venice
I have opened a separate blog for my travel photography portfolio as it is too large and diverse to fit neatly into this, my main blog on wildlife and wildplaces. There are some places I visit which are not particularly wild after all. Although I do still tend to see the wild side of things wherever I am. Some of the travel shots I take might be standard in style, but most are from my own personal viewpoint. I like to look for details in colour and form, and powerful compositions.

The first set is on Venice - which is just so photogenic - and I had fun exploring the canals and alleys  for something different in what must be one of the most photographed cities in the world.

So, if you would like to see my travel portfolio please click here.

'Dali' church