Thursday, 17 December 2009

Golden plover paper

A scientific paper, based on my work on golden plover in the Outer Hebrides in Scotland, has been published in Ringing & Migration 2009, 24, 253-258.

Counts of spring passage Golden Plover Pluvialis apricaria in north Lewis

The rich lowland grasslands of Lewis in the Outer Hebrides are used as foraging grounds by many thousands of golden plover in spring. The more boldly marked birds within these flocks are believed to be of the northern altifrons form which breeds in Iceland, and the Lewis grasslands are possibly very important for theses birds which stop there to feed before flying across the Atlantic Ocean.

A flock of golden plover of the altifrons type, feed in Lewis grassland. Some of the birds have very bold black and white plumage, probably males, while the less well marked birds are probably females.

A male Golden Plover of the southern apricaria form, which was breeding on the nearby moorland in Lewis. He is typically less boldly marked than the males seen on passage in the grasslands, as above.

Tuesday, 15 December 2009

Goshawks fledging

The brown goshawks which nest in the same woods as the tawny frogmouths are busy feeding fledglings now. They have had mixed fortune in their success, with one pair rearing three chicks, one with two, another with one and one pair failed to rear any. Prey remains below the nests included several young rabbits, two magpie fledglings and a galah.

An adult male brown goshawk calls in alarm as I approached his nest with young.

A female brown goshawk flies past me screaming in alarm. She is larger than the male and can be seen to be moulting tail and primary feathers.

Two fledglings stand on branches next to their nest while another has stayed in the nest.
The nest is typically set in a clump of mistletoe high in a tall yellow box tree.

Monday, 14 December 2009

Tawny Frogmouth study - 11

A scientific paper based on my studies of Tawny Frogmouths has been published in: Emu, 2009, 109, 327–330

Comparisons between nesting densities of Tawny Frogmouths (Podargus strigoides) in open- and closed-canopy woodlands
Stuart Rae

I mapped and measured the distances between the nests of contiguous breeding pairs of frogmouths in woods in the Australian Capital Territory. There were three types of woodland: partly cleared grassy woodland, open-canopy grassy woodland and closed-canopy dry sclerophyll forest. Although the nests were regularly spaced in all three sites, they were at different densities. The highest density of nesting birds was 0.05 nests ha–1 in partly cleared woodland; there were 0.02 nests ha–1 in the open-canopy woodland and 0.006 nests ha–1 in closed-canopy forest. This is the first survey of this type of these birds, and it is planned that a long term study will monitor the breeding birds over the years to test for any effects of habitat or climate changes on their densities and productivity.

Close-canopy dry sclerophyll forest, with tall grasses and small shrubs as ground cover on poor, thin gravelly soils.

Open-canopy grassy woodland, with richer soils and short grass ground cover - grazed by grey kangaroos.

Part-cleared grassy woodland with numerous wide glades between the trees, and similar richer soils and grazed grasses as in the open canopy grassy-woodland. This habitat seems to offer richer food sources, and perhaps the frogmouths' prey is more easily found and caught there as the birds tend to hunt over open ground from perches.