Thursday, 5 November 2015

Nest re-cycling

The male Tawny Frogmouth Podargus strigoides sits on the edge of the chough nest

Tawny frogmouths usually build their own nest, a simple platform of twigs and sprigs of greenery, although about one in forty nest records from my study of these birds in Canberra have been in old White-winged Chough Corcorax melanorhamphos nests. These are large, clay nests, which resemble bronze-age beakers set half-way along horizontal branches. In this case about fifteen metres up a Scribbly Gum tree. Frogmouth nests are often flimsy constructions, so perhaps they find these old firm structures as good bases for their nest. They add a few sprigs inside the cup, but don't fill it.

The female sits with the chicks - she has more red on her wings than the male

I have been monitoring the incubation, brooding and feeding rates of frogmouths over the years, studying differences in habitat and weather conditions. Some of this can be done by watching, but it is at times easier and less time-consuming to do this remotely with wildlife-monitoring cameras. So, with the help of Laura Rayner, who did the climbing to this nest, we set this one up, which was about fifteen metres up a gum tree. Once the camera was set and tested, we left the birds for the night and collected the camera the next night. I only approach these birds at night as I do not like to disturb them during the day when they can be vulnerable to predation. They behave so confidently at night, and these birds were feeding their chicks as we were setting up the camera a few metres away.

The chicks, at about two and a half weeks old, were beginning to fill the egg-cup nest

In this case, the adults fed the chicks seventy times overnight, so that was perhaps thirty-five feeds per chick, if they received equal shares. I don't know as I can't identify each chick in all the shots. About half the feeds were in the first two hours after dark, then the feeding rate decreased as the night progressed. And each adult only brooded the chicks for one period of about ten minutes, most of the time the chicks were alone in the nest.

Then as dawn approached the male came in to cover the chicks for the whole of the next day, for it is the male who guards the chicks all day, while the female roosts in a nearby tree. To watch some footage from the camera click here.

A chick peers over the lip of the clay nest

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