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!