Tree-creeper bill shape

Adult male White-throated Treecreeper

One of the advantages of mist-netting birds for banding is the opportunity to see them as we seldom have a chance to do so when they are flitting about the woodlands or wherever they live. While we were banding, aging, sexing and measuring this White-throated Treecreeper Cormobates leucophaeus during the same study as the previous blog article below, I noticed just how fine its bill was. There is a graceful curve when seen side on, but when viewed face-on, the bill can be seen to be remarkably tapered to a point. This is an adaptation for probing into cracks in tree bark, where they hunt for their food; tiny invertebrates.

The sleek lines of the treecreeper's bill - superbly adapted for reaching and grabbing tiny insects under bark

In comparison, other birds we caught that day included the Western Gerygone Gerygone fusca with a fine pencil-pointed bill for feeding on the tiniest of insects. Very fine, but straight and simple in line as it has no need for any further specialist shape like the treecreeper.

The tip of  this Western Gerygone's bill is polished by contact with the surfaces it has lifted insects from

There were also honeyeaters, which have slightly curved bills for probing into flower-heads to sup nectar, but their bills are mostly sturdy like that of this White-plumed Honeyeater Lichenostomus penicillatus as they also eat insects. The bill is very much thicker than that of the treecreeper.

The White-plumed Honeyeater has a slightly curved bill for accessing nectar in flower heads

And we caught a the generalist insect-eating Rufous Whistler Pachycephala rufiventris.  It has a broad, thick bill with a curved tip on the upper mandible, which enables it to catch insects on the ground or in the air and hold them firmly. Only when we held these birds successively in the hand did I appreciate just how finely tuned the treecreeper's bill is. Evolution is marvelous. 

An adult female Rufous Whistler: the hooked tip to its bill helps it hold prey tight

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.

Sugar Glider

A tree came crashing down today

While I was out looking for Tawny Frogmouths today I heard a crash and looked around to see an old tree fall down. I thought it might be interesting to see what animals had been disturbed, or lost their home as I could see that the tree was very old and had some cosy holes for animals to sleep up in.

Sue enough, as I approached, a Sugar Glider  Petaurus breviceps slipped out of a broken branch and scuttled up the nearest standing tree. It wasn't too alarmed by my presence, but did go high up very quickly. For that is their strategy to escape, they can climb well, but they can fly too. And when it reached the highest branches it simply jumped into space and glided onto the next tree about twenty metres away. It landed on the top of another dead tree which it clambered down until it found a hole it could wriggle into. And that was that, a new home, safe from predators.

The Sugar Glider dashes up a tree

Once up high, the glider stopped to watch me. The folds of skin which help it glide can be seen rippled along its flanks.

Meanwhile, take a look back at the first picture. There are a pair of frogmouths up in the tree, in the top left. I noticed the male's tail protruding out from the nest after the glider had disappeared and I could re-focus my attention to my original purpose. 

The male frogmouth is on the left, on the nest, his partner is on the branch above

Tawny Frogmouths at night

The moon and Venus above the female frogmouth

I was out watching the frogmouths last night with Steph and Matt. There were a pair which appeared with fledged chicks last year from an unknown nest site, so we staked out the area at dusk. The female was calling from her daytime roost perch for ten-fifteen minutes as the light faded. Then as it became truly dark she shifted to another perch and continued to call her rapid repeating 'ooom-ooom'. The call is distinctive, but so soft, we wondered how far away her mate was. The call only carried to our ears for about fifty metres. Do they do so to avoid attracting attention from their main night-time predator, the Powerful Owl? Then the male swooped in silently from the shadows and landed right next to her. She twitched her tail, he jumped onto her back and they mated for a minute or so. He then went off and hunted, catching an insect from some foliage up in a tree. She flew over to their nest site and continued to call. 

So, we accomplished our quest to find the nest site and all this happened in about half an hour immediately at the onset of true darkness. There is so much to see in the dark.

The distinctive silhouette of a Tawny Frogmouth - a broad, bushy head and a tapering tail 

Bearded Dragon

Flat out

The days are warming up and the first of the larger reptiles have been out and about. The Shinglebacks Trachydosaurus rugosus are wandering slowly about the bush and others like this Bearded Dragon Pogona barbata are spending much of the days warming themselves up in the sunshine. This one was well camouflaged with its dusty skin matching the open dirt between the grass tussocks. It lay motionless as I stepped past it; its legs hung down along its tail, its skin spread out and the whole body aligned with the sun, all to maximise capture of the radiant heat.

It seemed to be trading off the powers of its concealment against the expenditure of its limited energy, having just warmed up a little and not being very active yet. For it was keeping a steady eye on me in case I did after all pose a threat and it would have to use that little energy to flee.

An eye watches through the camouflage