Thursday 1 April 2010

Merlin papers

I have two scientific papers published in the march issue of Scottish Birds, the journal of the Scottish Ornithologists' Club. http://www.the-soc.org.uk/


A young merlin grips tightly to a piece of prey - the remains of a meadow pipit

The first paper describes what merlin in the Isle of Lewis eat in the breeding season. This is mostly meadow pipits, the most abundant bird of the moorland where the merlin live. The Lewis peatlands, are one of the best breeding habitats for moorland waders in Britain, with high numbers of dunlin, golden plover and greenshank, and although the merlin do eat dunlin in particular - the smallest of these waders; the smaller pipits, skylarks and wheatears are their main prey.

A brood of four merlin chicks huddle quietly in their nest set on the ground.

The second paper discusses the high density of merlin on the island, which is one of the highest in the world. This is likely because there is abundant food, as described in the first paper, and possibly because there are no indigenous terrestrial predators such as foxes, which are the main causes of nest failure on the mainland. The main predator of merlin in Lewis is the golden eagle. Merlin nest on the ground in the moors where eagles hunt and the white merlin nestlings must be easily seen and killed. Yet despite this predation, the merlin rear young from most nests, and these are ample for maintaining the high numbers of breeding pairs each year.

Four merlin chicks and one unhatched egg - better concealed than the nest above as it is under heather, out of view of hunting eagles overhead.

A typical merlin nest site in Lewis - set on heather clad bank adjacent to the wide flats of the peatlands.

For more information contact stuart@canberra.net.au

Monday 29 March 2010

Banding at Charcoal Tank

At the weekend I was banding birds as part of a long-term study at Charcoal Tank Nature reserve, out near West Wyalong in NSW. The project is ran by Mark Clayton and two others there were John Rawsthorne and Alistair Bestow.

Most of migrants had left as autumn is now here and so birds we caught were all local residents. One speciality of the area is the Shy Heathwren shown below. The photos below clearly showing the wingflashes of white which easily distinguish it from the closely related chestnut-rumped heathwren - both species having chestnut rumps does not help to identify them.



Among the other birds we caught were rufous whistlers, a male and female shown here together side by side showing the very different plumages of the two sexes. Most birds we caught were in fine plumage with new sets of primaries and body feathers freshly coloured. By the end of the next breeding season they will be a various stages of moult as they replace their worn and sun-bleached feathers.


There were numerous red-wattle birds, white-plumed honeyeaters, blue-faced honeyeaters and spiny-cheeked honeyeaters feeding on the flowers of the red-ironbark trees. Here is a close-up portrait of a spiny-cheeked honeyeater which shows the spiny feathers on its cheek. It is an adult as it has reddish throat feathers and a bright pink bill and gape. Young birds have yellow throats and duller bills. Note how like all honeyeaters the birds tongue is often pushed out beyond the bill exposing the brush-like tip which helps these birds draw nectar from flowers.

Friday 5 March 2010

Magazine article



Leopard Magazine, which covers all topics of interest local to north-east Scotland have published an article which I wrote on the various survival techniques employed by animals and plants on the mountain tops. The topic was inspired by the recent snowy winter in the north-east and I describe how adaptations in form and behaviour enable species to not only survive in such conditions, but thrive.


An abbreviated version of the article is available online at the link below - the text is complete, only most of the photographs are omitted. I also supplied the photographs.



http://www.leopardmag.co.uk/feats/276/strategies-for-survival

Friday 15 January 2010

Owlet nightjars

I do not like full-flash photographs of night animals as that is not how I see them or remember my experiences with them. So here is a shot of an owlet nightjar as it emerged from its roost just as the last light was fading away. They can be found by listening for calls which they give as they prepare to leave their hollows. Then when they fly off they really take on spectral form as they slip silently through the trees.

I have been out on a few evenings/nights recently watching owlet nightjars. These are not owls, nightjars or frogmouths, but are in a family of their own. Taxonomists still debate where they fit.

Wherever they fit, they resemble owls with their large almost forward-facing eyes and their habit of nesting and roosting in tree hollows. Their bodies are similar to the slender true nightjars, but their feet and legs are stronger, enabling them to sit across branches and climb in and out of holes. And their wide bills with side-bristles also resemble nightjars, or perhaps swifts and some claim these are their closest relatives.

My interest in them comes from their main habitat - woodland, which they share with frogmouths. Both species live in the same woods and seem to forage in similar styles by pouncing on prey from a lookout perch, or rummaging around in the leaf litter. Do they successfully co-habit because they eat different prey, differentiated mainly by size? I would like to know. One advantage the owlet nightjars have over the frogmouths is that they can expand their range beyond woodland and live in man-made hollows or in rock crevices. As frogmouths rely on their camouflage for safety when roosting during the day, they need trees (see earlier postings).

Monday 11 January 2010

Sparrowhawk in the garden


This morning, while sitting reading on the veranda, I heard a chorus of alarm calls from the garden birds. So I went over and straight away found a male collared sparrowhawk sitting in the tree above the drinking pool I have built for the birds. In the photograph below he was right in the centre of the thick green foliage.




He was quite undisturbed by me, simply continuing to scan around with those big yellow eyes, watching the small birds which were still alarm-calling from the nearby bushes.




I never see sparrowhawks in the garden during the breeding season, yet every year they turn up to hunt around the drinking pool, feeding station and the chicken shed where sparrows are always present, scavenging for split corn. The sparrowhawks come into the garden from now, mid-summer, to late winter, and I have seen adult and young birds of both sexes hunting the same area at different times, sometimes in the same day.

The bird shown here is moulting new feathers to his tail. The two outer feathers are still short - less than half the full length and appear here as short dark and grey, not protruding farther than the wing feathers. Two fully-grown new tail feathers lie in the centre of the tail, and appear here fresh and bright with distinct barring and firm bottom edges. The feathers either side of these two are old, as seen by their faded colouring, indistinct barring and frayed bottom edges.

The conventional method of distinguishing collared sparrowhawks from the closely related and similarly plumaged brown goshawk, is to class the tail as rounded or square edged at the tip. If square it is a sparrowhawk, round a goshawk. Here, while the bird is in moult it is not such an obvious plumage characteristic, although the more sharply square edges of the two ingrowing outer feathers hint at a more typical shape soon to form. The species also differ in size, goshawks being the larger - about the size of a Eurasian sparrowhawk. This male was obviously a sparrowhawk by his small size. A large female goshawk would be equally obvious as such by her large size. Most ambiguity occurs between the male goshawk and female sparrowhawk which can be similar in size.


Another feature I like about this male was the way his breast feathers were all ruffled, not neat and tidy as usually portrayed in illustrations. A real bird!