On Monday 1st February 1993 I was taken to see the nest of a 'small black and white bird like a wagtail' built at the top of a platform near some conveyors in the processing plant at the Argyle Diamond Mine.
When we reached the site an Magpie-lark left the nest and perched on a beam about 10 metres away and called vociferously. I was told that this wasn't the bird that had mobbed him the day before.
The nest was a typical Magpie-lark nest made of mud and lined with some grass. There were three pale (but with brown blotches) eggs in the nest. It was located on an electrical cable (about 3cm thick) beneath an electrical switch board. It was about 10 to 15 metres above the ground.
A Willie Wagtail gave a warning chatter and then hovered about a metre from us before perching on a beam about three metres above us. It had been sitting on a nest about four metres to the right. The nest was a miniature version of the Magpie-lark nest although with more grass in the structure. It was also based on the electrical cable close below a beam about 15cm above it. There were three eggs very similar in colour to the Magpie-lark but much smaller.
Magpie-larks are abundant at Argyle with many nests in trees around the process plant, the village, the Alluvials plant, the airport and near the roads. This is the first I have seen built in the structure of a building.
Willie Wagtails are common at Argyle. This is the first nest that I have observed but a nest had been reported to me during the previous wet season (possibly the same nest and pair). The nests that I have seen elsewhere in Australia were difficult to locate in a bush or tree branch within a couple of metres of the ground.
There was plenty of nesting material available all year round. The conveyors nearby carry the wet diamond ore after crushing with some spillage on to the structure and the ground below. Across the road about 30 metres away is a drain with wet soil/mud, and there is some patchy ground vegetation nearby.
Both nests were in good condition despite the extended rain that had fallen in the previous week and the occasional gusty winds. The switch board and beam had been well chosen to provide protection from the elements. My main surprise was that these two fairly aggressive birds had chosen to nest so close together.
They were both very vociferous about our presence, but were surprisingly not very aggressive, possibly because of our hard hats. While access to the location is easy, few people would probably need to go there during their normal duties.
Postscript : It was reported to me that all three Magpie-lark and three Willie Wagtail eggs hatched. However, a few days later all Willie Wagtail chicks had gone. I don't know what happened to them. The three Magpie-lark chicks fledged.
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