Hiding the Nest

Predators seem to destroy many nests and eat many baby birds. Kookaburras, currawongs, butcherbirds, ravens, even magpies find it hard to resist an easy meal of nestlings. I fear for small urban birds like Grey Fantails and Willie Wagtails as I have witnessed several times the tragedy of hours of work and care – constructing nests, sitting on eggs, feeding young – come to nothing when one of those bigger birds drops by for lunch.

Biologists call it an arms race – the prey bird has to find new ways to outwit or defeat the predator, and there are many intricate strategies, while the predator, in turn, learns new ways to hunt them. Should either prey or predator get too far ahead, the other will struggle to survive.

Some years ago on this blog, Macwake detailed the story of Dusky Woodswallows with a conspicuous nest in a Sheoak losing their brood to some unknown predator: Precarious Position. The story surprised me because I have observed that Woodswallows (genus Artamus) frequently nest cryptically behind a piece of lifted bark on the side of a tree. If they are so foolish as to nest in the open, expect the predators to win the arms race.

I once witnessed a season where a huge mixed flock of White-browed and Masked Woodswallows descended on a Red Gum forest – every spare piece of dislodged bark harboured a nest and the air was alive with busy adults zooming around, feeding the brood.

Here is a Dusky Woodswallow pair (A. cyanopterus) I observed recently with a more typical, cryptic nest site. I never actually could see the babies even though they were obviously being fed and it was only at shoulder-height. The nest is tucked in behind the bark.

My guess is they raised the young successfully.