James and I spent some time wandering around Bicentennial Park this winter. The Badu Mangrove Wetland was fun to walk through because there was a certain eeriness to it when no-one was around. It also looked so different to other urban parks, making the afternoon stroll feel more adventurous than it actually was.
Badu Mangrove Wetland in Bicentennial Park, Sydney. The shoot-like growths are the aerial roots of the grey mangrove (Avicenna marina).
The mangrove forests were usually very still, but for a few mallards (Anas platyrhynchos) and Australian white ibis (Threskiornis molucca). Hence, the squawky call of the yellow-tailed black cockatoo (Calyptorhynchus funereus) caught our attention instantly. There was a small flock (c. 10) of them swooping through the forest. They took periodic stops on the mangrove trees, seemingly looking for something. We followed them, but an aggressive move forward eventually scared them away, so we stopped.
It wasn’t intentional, but somehow, later down the track, our paths crossed again. We took our time to walk through the forest, so the cockatoos must have made a lot of stops along the way. A pair of the cockatoos landed on a bowed branch near an open mud bank and stayed there despite our presence. They seemed to have an arrangement – one was on guard duty, while the other started pecking and gnawing a rotten section of the tree.
Turns out they were foraging for a little grubby treat – the larvae of wood-boring beetles!
Yellow-tailed black cockatoo (Calyptorhynchus funereus) foraging for larva of wood boring insects in Badu Mangrove Wetland in Bicentennial Park, Sydney. Photographs taken by David Noble.
The experience reminded me of remnants of a feeding frenzy in Hokkaido. The great spotted woodpecker (Dendrocopos major) detects the presence of beetle larvae in trees by listening for the sound of larvae chewing wood or tapping on the wood to see if there is a hollow section, an indication that larvae are inside. A woodpecker will typically bore multiple holes in the one tree to maximise the amount of insects excavated.
Japanese Red Pine (Pinus densiflora) with a feeding hole bored by a Great Spotted Woodpecker (Dendrocopos major) in Nopporo Forest Park, Sapporo, Japan
Not fun to be wood boring larvae!
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Cloudpot 