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.

Brown Treecreepers: 
How to tell their age and sex

I am building up a portfolio of photographs which show how to age and sex various species of Australian birds. These will be posted in a separate blog, but for now I will upload them to this site and would be grateful for any comments prior to collating them on the new site. The birds have all been caught in mist-nets during long-term field studies, mostly run and organised by Mark Clayton or Richard Allen, to whom I am grateful for their knowledge in confirming the birds' plumage patterns, particularly some of the more tricky species.

As a sample of how I intend to progress with the project, here are a few images to aid people in aging and sexing Brown Treecreepers Climacteris picumnus, following differences in their plumages.

 

Adult (1+) male Brown Treecreeper
04/11/2012, West Wyalong, NSW.

The bird on the left is an adult male, categorised  as 1+, a bird of one or more years old. It is recognisable as an adult by the bold eyestripe and breast markings. The sex is determined by the black freckle spots arranged in a necklace around its throat. The throat's rich buff-orangy colouring is also indicative of age, although more comparative and less useful as a guide if only one bird is seen at a time.

The dark dashes on the breast feathers are the brown edges to the breast feathers which have a wider band of white/buff down the shaft than in those of birds in their first year. Therefore the dashes on the adult birds are farther apart.

First-year (1, juvenile) male Brown Treecreeper
15/12/2013, West Wyalong, NSW.

The bird on the right is a first-year male,
categorised as a 1 juvenile, as it still has folds of skin around the base of its bill, the remains of its juvenile gape.

Again, it has a black necklace of spots. Females, adult and juveniles/first-year birds, have rusty-red spots on their necklace.

First-year birds of both sexes have narrower dark-fleck patterns on their breast feathers. This being due to narrower bands of white along the feather shafts than on adult birds.

The same adult male

When the adult's head is seen from the side, there is a distinct contrast between the prominent eyestripe and buff supercilium, highlighted by a faint white top edge. These markings on the first-year bird are less obvious, as is the contrast between the grey tail tips and the rest of the tail, which in the adult is strong due to the darker upper tail colour. There is a similar difference between the dark primaries and primary coverts of the adult and the grey/brown colour of those of the first-year bird. 

When seen close in the hand, the tips of the adult bird's greater coverts are faded and frayed, while those of the first-year bird are fresh with buff tips. This last point is also a useful diagnostic feature for aging birds of many other species and will be repeated when applicable in further aging and sexing of birds notes as I compile them.

The same  first-year, juvenile.