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.

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