Black-eared Cuckoos

A first-year Black-eared Cuckoo on the left, adult on the right

In a recent post I discussed the plumage of a Black-eared Cuckoo Chrysococcyx osculans which we caught at Charcoal Tank Nature Reserve, then last weekend, 14-15 December, we caught the same bird again, along with two younger birds which were definitely in their first year. A useful comparison.

Once again I am grateful to Mark Clayton who organised the trip as part of a long-term study of birds in the area.

The second first-year bird

One of the first-year birds

The adult bird (right) as described in the earlier post, had a fully marked face and a richly coloured throat and breast.

 

Both first-year birds had faintly marked faces, with dull throat and breast colouring.














The moult sequence and timing of the various feathers of this species is poorly known, with the information used for the synopsis in the Handbook of Australian, New Zealand & Antarctic Birds being based in parts on only a sample of three birds. And we only have a sample of three. Therefore, I am open to discussion on any points raised.

The two young birds on the left have dull grey-brown rumps and tails; the adult bird on the right has a grey
rump contrasting with a dark tail. The first-year birds have faded feathering overall, while that of the
adult bird is fresh, unfaded and lustrous like other birds of the genus

Although synchronous growth bars on the tail are used as an indication of a bird with its original tail feathers, it seems from comparison between these birds that the adult bird might not really have synchronous bars. Perhaps the feathers can grow and align to seem to be of the same age. The freshness and dark unfaded colouring of the adult bird's tail would seem to be recently grown. Yet, apart from the apparent synchronous tail growth bars, the bird has an otherwise adult plumage. Also, its tail is only slightly worn at the tips, and it has distinct white tips, as mentioned in the previous note, unlike the first-year birds which both have well-worn buff tips. Such bold white tips (compared with buff tips of definite young birds) are often an indication of an adult bird. I suggest that this is indeed a true adult bird which hatched at least two breeding seasons ago, and the first-year birds hatched one breeding season ago.

The first-year birds also had faded, frayed secondary coverts with buff tips, and darker, unfrayed primary coverts

There is another trip to Charcoal tank planned for January, so perhaps if we catch these or any other Black-eared Cuckoos we will be able to note any moult  features which could help to determine this species moult pattern. 

Breeding season feathers

Adult Laughing Kookaburra

I was out helping Mark Clayton with several others at a cooperative bird-banding site over the weekend, out by West Wyalong in New South Wales. The season is warming up now and there was a heavy fall of rain several days prior to our visit. Many of the birds were breeding, and I noted how we were catching more male than female birds, probably because the females were doing more incubating.

It was also a good chance to see adult birds in full breeding plumage. Although, as most of them had moulted into that plumage months ago, some of their flight feathers were beginning to look a bit tatty. This Laughing Kookaburra Dacelo novaeguineae, was an adult, although it could not be sexed because it did not have a large blue patch on its back like a primary male would have. As it only had a small blue patch, too small to even see in these photographs, it could have been either an adult female, a young female or a secondary male. Kookaburras are cooperative breeders, and the males also incubate the eggs, so even the presence of a brood patch was no help in sexing this bird.

The bird had a well developed brood patch: a large patch of bare loose skin, with a rich vascular supply

It was still early in the breeding season, so the birds had not yet begun to moult. They all had full sets of old flight feathers on their wings and tails.

A full set of flight feathers

Some of these feathers were beginning to fray at the tips, through wear and tear as the birds go about their business, flying through branches and catching their tails on the ground. The central tail feathers are particularly prone to wear as they project farthest and take most of the abrasion, so they are usually the first to show signs of age. Most of these birds will begin to moult out these battered feathers and grow replacements as the breeding season progresses.

The pair of central tail feathers on this kookaburra's tail are well frayed.