Bushland vandals or ecosystem engineers?

Earlier this week I had a fascinating encounter with a party of White-winged Choughs. I came across the group feeding in typical fashion, ‘gardening’ a patch of ground that perhaps an hour earlier had been replete with lily and orchid leaves. The patch, about 20 metres square, had been so extensively cultivated that only a handful of plants remained. This is a common sight in the bush around Newstead and I’ve often heard people comment about ‘damage’ caused by these remarkable birds. They certainly must consume thousands of tubers each season!

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White-winged Choughs ‘gardening’, Bruce’s Track, 22nd June 2016

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Before, and …

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after!

What struck me as I watched on was that the group seemed particularly enthusiastic about one area within the patch and that some of the birds had fur attached to their bills. As I wandered over the choughs flew off and I discovered the object of their attentions. The decomposing remains of a Grey Kangaroo had created a ‘hotspot’ for invertebrates and the choughs were feasting on insects as well as tubers.

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Remains of Grey Kangaroo carcass

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The choughs foraging around the carcass

The actions of the choughs reminded me of a recent article about the importance of ‘diggers’ in the Australian landscape. White-winged Choughs are a classic example of what ecologists refer to as ‘ecosystem engineers’, that is any organism that creates, significantly modifies, maintains or destroys a habitat. As the aforementioned article discusses, our terrible record of mammal species loss has had a significant impact on the health and function of ecosystems across the continent.

White-winged Choughs are now perhaps partially filling the role that once would have been shared with bandicoots, bettongs and potoroos – sadly they are all long gone from the Newstead bush.

2 responses to “Bushland vandals or ecosystem engineers?

  1. It is worth noting that wolf spider burrows are a common target of Choughs. I have spent many hours lying in the dirt photographing spiders for Lynne’s book and have often observed groups of Choughs targetting areas where there are groups of wolf spider burrows. These burrows are hard to see unless you are familiar with them.

  2. Chris Johnston

    Thanks Geoff. It made me think of the importance of humans as cultivators too – the early colonials commented on the harvesting of tubers by Aboriginal people which was clearly an ongoing and sustainable harvest. So scratching around in the soil can be good for species survival too.

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