Tuesday, 13 May 2014

Young Honeyeaters

The gorgeous bib of a Striped Honeyeater,
the feathers from which it gained its species name lanceolata - spear-shaped
Continuing on from the previous post on aging birds caught and banded at Charcoal Tank Nature Reserve last weekend, here are some points on identifying young Striped and Fuscous Honeyeaters, Plectorhyncha lanceolata and Lichenostomus fuscus.

It is the head and shoulders that are striped,
and its bill is very finely pointed, from which it gained its genus name
Plectorhyncha - a spear point bill
Only one Striped Honeyeater was caught, which is understandable as they forage mostly high in the tree canopy. That was a first-year bird, moulting out from its immature plumage to that of an adult, ready to breed in a few months time. The bird had a fully striped head and shoulders like an adult, so the best feature to identify it as a young bird was the amount of buff tips to its wing coverts. The tips of its primary and secondary feathers were chipped and worn with notches and other pieces of the tips missing. This is a sign of age of the feathers, not of the bird, for it will moult these out and grow a fresh set once a year.

Worn and faded coverts, primary and secondary feathers of a young bird's wing
Buff tips on the greater coverts are often a good indicator of  a young bird's age as I have mentioned before. Here, the  two outer greater secondary, all the greater primary, and at least two median primary coverts have buff tips. The greater primary coverts are particularly worn at the edges. The fresh adult grey colour of the new inner secondary coverts and the alula contrast with and emphasise the faded and ragged old coverts.

The two outer greater secondary coverts are buff-tipped, all the greater primary coverts are faded brown and worn
 - while the fresh grey alula sits among them  
Only one young Fuscous Honeyeater was also caught, and although it was in immature plumage, with a pale base to its bill, adults also have this feature when not breeding. Other markings are more rigorously diagnostic of a young bird.

The plumage of a first-year Fuscous Honeyeater does not differ much from that of an adult
The species diagnostic feature of a yellow plume with a dark upper edge, on the side of the neck, was only beginning to grow in, and there was still a juvenile gape - the loose yellow skin at the base of the bird's bill.

There was only a hint of a yellow plume on the side of its neck
The back of the bird's head, from crown to nape, had flecks of buff feathers, very unlike the uniform grey-brown-olive colouring of an adult bird.

Buff-tipped feathers on the nape identify this bird as a bird in its first year

Monday, 12 May 2014

Olive-backed Orioles

First-year immature Olive-backed Oriole
I was banding birds at Charcoal Tank Nature Reserve again last weekend, with Mark Clayton, Harvey Perkins, Peter Ewin, and others. It is now late autumn and aging some of the birds is becoming difficult as they lose their juvenile and immature plumages ready to moult into full adult breeding plumage, before the next breeding season begins in a few months. Further species will be highlighted in later posts, but for now I have posted some images of two Olive-backed Orioles Oriolus sagittatus which we caught. One was a first-year immature bird and the other a second-year immature bird, which was particularly difficult to ascertain an accurate age for, as so many plumage features are comparative. Hopefully these images will help others to discern the ages of Olive-backed Orioles in future.

Second-year immature Olive-backed Oriole
The presence of buff-tipped wing coverts is always a good feature to look for in young birds and the first-year oriole had obvious buff tips on all its greater and median coverts.

Very obvious buff tips to the coverts - 1st yr
The second-year bird only had a few buff-tipped greater coverts, which were not obvious even when the bird was held in the hand. The second-year bird's primary, secondary and tail feathers were also darker than those of the first-year bird, similar to those of an adult.

Only a few buff-tipped greater coverts - 2nd yr
Adult Olive-backed Orioles have grey wing coverts with dark centres, and no buff tips. The image below is of an adult female's wing, from a photograph of a bird caught in a previous breeding season, when it was confidently aged as a breeding adult bird.

Adult wing coverts with no buff tips
The facial markings were also good for determining the birds' ages. The first-year bird had an obvious cream-buff supercilium, a dark eye and bill.

Obvious supercilium and dark bill - 1st yr
The second-year bird had a faint supercilium, red eye and a brownish bill with a pink flush. The streaking on its chin and throat are very similar to those of an adult female, and a second-year bird cannot be sexed until its plumage shows either a heavily streaked chin/throat or not, once its bill has become bright red.

Faint supercilium and brown bill with a pink flush - 2nd yr
The last two images are of adult Olive-backed Orioles caught in a previous breeding season at Moruya while banding with Anthony Overs. Neither bird has a noticeable supercilium, their irides are red and their bills are bright pink.

Adult female Olive-backed Oriole
Adult females have a streaked chin and throat, while the males have more of a green hood extending down around their throat. The females also have heavy streaking on their backs while the males only have light streaks.

Adult male Olive-backed Oriole