Sunday, 30 August 2015

Prospecting ducks

A pair of Australian Wood Ducks Chenonetta jubata above a potential nest hole high in a tree

It's not only parrots that nest in tree holes in Canberra, although there are so many around it seems like it sometimes. Tree holes are prime real estate for a many animals; brush-tailed possums and sugar gliders, kookaburras and treecreepers, bats and smaller creatures such as spiders. Also, as Canberra has lots of open grassland in parks and road verges, it has a large population of wood ducks, which are grass-eaters. And they all need nest holes too.

The other day I watched a female wood duck cooing and grunting from high in the branches of an old eucalyptus. She was prospecting for a nest hole and seemed to have found a suitable one if only she could work out how to fly into and land on its rim - the hole was on the underside of a thick limb.

The female was the more interested in the hole, the male was simply following her, protecting her

She spent more than ten minutes bending over and peering into the darkness, while the male spent most of that time preening himself. The drake's purpose is to protect his mate from predators and any other suitors. So, this one's investment is in her and the fertilised eggs she was carrying. Her investment is a safe place to nest, hidden away from danger while she incubates the eggs. She will be in her nest hole, whether this one or another, for about a month, only coming off perhaps once a day to feed. Then when the ducklings hatch, she will encourage them to jump down from the nest hole, then lead them away to the nearest water for safety, and surrounding grass for the ducklings to eat.

She seemed to like the hole but wasn't sure how to get into it?

Monday, 17 August 2015

Spring Plumage

Diamond Firetail Stagonopleura guttata in bright adult breeding plumage
Spring is ever nearer in the south-east Australian bush and many of the birds, especially the passerines, are beginning to breed. Which means that they are now in full breeding plumage and looking their best.

Over the past weekend I was part of a team mist-netting birds at The Charcoal Tank Nature Reserve in south-western New South Wales, as part of a long-term study of birds in the area, organised by Mark Clayton. And it was clear by the condition of the birds' plumages that they were fit, healthy and ready to breed.

Diamond Firetail 
There was a flock of Diamond Firetails feeding on grass seeds along the edge of the reserve and they were dazzling as their red rumps flashed through the grasses. The bird shown here is an adult in full breeding plumage, with all the feathers on the head and breast clean and fresh. For these are the feathers which any potential mate or competitor would see when assessing its fitness. However, the flight feathers, the primaries secondaries and their coverts were a bit tatty, with chips and worn edges. For these feathers would have been moulted and re-grown at the end of the previous breeding season, and they will be again at the end of the current season, but for now they are still perfectly functional and there is no need to replace them yet. Birds are almost constantly moulting part of the their plumage at any time of the year, and for the moment it is the bright signalling feathers that need to be in top condition.  

White-plumed Honeyeater Lichenostomus penicillatus
It is not only their feathers which are spruced up for breeding. The white-plumed honeyeaters which we caught, also adopt shiny dark colouring to their bills - they are duller and greyer when not breeding. This adds impact to their dark eye and the slight fringe of dark feathers on their neck, next to their white-plume, which the dark colouring emphasises. By the time the birds are half-way through the breeding season, the best of these colours will have begun to fade.

Chestnut-rumped Thornbill Acanthiza uropygialis
Even the little-brown-jobs, the small dull coloured birds adopt brighter plumage. This chestnut-rumped thornbill had a particularly well marked face pattern, in relative terms, and it's only when we see them up close, in this case in the hand while ringing/banding them, that we can appreciate the detail of these tiny birds' markings. Although to a bird's eye, they see things across a wider spectrum than us, these markings probably also signify the birds health, fitness and hierarchy in the flock, only more demurely.

Chestnut-rumped Thornbill - face
The sexes of all three previous species have similar plumages to one another of their species, they are monochromatic to our vision - but probably not to their own. For birds can see ultra-violet colours and in some species this has been found to be used in their markings to differentiate between the sexes. Do these species sport such colouring?

Golden Whistler Pachycephala pectoralis - male
Some of the brightest birds in the study were the male golden whistlers, and if their plumage is enhanced with ultraviolet colouring they must be amazing to see through a whistler's eyes. This species is dichromatic - there is a colour-difference between the male and female. The female is an almost overall grey colour, which is fit for purpose, as she incubates the eggs and broods the young. That involves a few weeks of her life each year, spent sitting on a nest set amongst grey-barked branches, so the grey colouring acts as camouflage while she is on the nest. The species has evolved for the females to be camouflaged while the males are brightly coloured to show off their fitness and hence value for a female to mate with, or for another less-brightly coloured male to avoid.

Even in her grey plumage, the female can be seen to be healthy and fit to breed as her feathers are clean and fresh. She too is fit to breed.

Golden Whistler - female

Thursday, 6 August 2015

Snuggled up

It's late winter in Canberra with frosty nights and sunny days, and the birds are beginning to show springtime behaviour. The Tawny Frogmouths are drawing closer to their breeding sites, moving in from more distant perches to be close to their nest sites. They will be building their nests soon. Although none have started to do so yet, I have seen birds with well-built nests by this date in previous years, with the earliest eggs laid on the 12th August. Meanwhile, they are making the best use of the sunshine as they roost during the day.

A pair of Tawny Frogmouths Podargus strigoides roost by day in a gum tree
the smaller female sits closer to the trunk as is usually the case - for protection by her mate?
They are medium-sized birds, about the size of a Tawny Owl, and live mostly on invertebrates. However, they have a slow metabolism and as insects and such creatures are not abundant during winter, they move as little as possible, slow down their metabolism even further and sit in sunny situations, all to conserve energy. And to do so while daytime predators are about, they have evolved excellent camouflage for protection.

A pair of frogmouths sit high on a sunny branch
Yet, they don't stay completely motionless all day. This pair mostly roost farther along the branch towards the trunk, but as the sun has crossed the sky, they have shuffled along the branch to stay in the sunshine. Today was cold.

The spot where these birds usually sit is farther to the right, as can be seen by the worn red bark on the branch and a fluff of cast down below where they normally sit.
The frogmouths sit fluffed up and huddled into a rounded shape to keep warm, and by snuggling up close to one another the pair gain extra warmth.

Saturday, 1 August 2015

Scottish Top Ten 2015

I have now returned from my field-trip to Scotland and have a few thousand photographs to catalogue. So it is time to reflect on what I achieved work-wise and image-wise. I thought the first thing I should do is pick out a top ten selection of photographs. These are not necessarily the best photographs, in quality or technique, but they are the ones that I consider as capturing the essence of my days in the field, the places I visited and the wildlife I saw.

And now that I have posted them I have already thought of others which could just as easily have fitted the bill.

Stac Pollaidh from Beinn nan Eoin

Kyle of Durness from the summit of Beinn Spionnaidh.

Golden Plover Pluvialis apricaria -  with snow on the Cairngorms in the background.

A Dunlin Calidris alpina - on breeding grounds on a hilltop in the eastern hills

A Mountain leveret Lepus timidus - lies motionless, as they do all day, for concealment from predators.

Mountain Avens Dryas octopetala - on a Sutherland coastal cliff.

Wild Pansies Viola tricolor  - a dense bloom in sand dunes.

Kittiwake Rissa tridactyla - juveniles soon after fledging.

Rock Ptarmigan Lagopus muta - a hen steps over boulders in the Cairngorms.

Golden Plover chicks - puffs of gold, the most beautiful of wader chicks.