Fan-tailed Cuckoo egg in Scrubwren clutch
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| A Fan-tailed Cuckoo egg with two of Large-billed Scrubwren |
I was down in the Shoalhaven area a few days ago and while out for a walk through some riverside forest I found a Large-billed Scrubwren
Sericornis magnirostris nest. I saw the adult bird flush as I walked by and was surprised to discover that it had built its nest inside an old nest of a Yellow-throated Scrubwren
Sericornis citreogularis - on subsequent research I discovered that this is common behaviour of the species. Then when I inspected the eggs there was a cuckoo egg amongst the scrubwren clutch. The egg were likely from a Fan-tailed cuckoo
Cacomantis flabelliformis - as scrubwrens are common hosts of these birds eggs and young, and there were a few of these around the area, but no other cuckoo species.
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| The cuckoo egg is noticeably larger than those of the scrubwren |
There were two scrubwren eggs, but whether there had been three and the cuckoo had taken one out is not known. The cuckoo egg was quite a good mimic of those of the scrubwren, although slightly larger and more spotted overall, and a little lighter in background colour. The scrubwren eggs also had more defined rings of spots around the broad end, especially one of the eggs. There was a faint ring around the cuckoo egg, but not very distinguishable.
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The cuckoo egg has a faint ring of spots on the broad end like those of the scrubwren eggs,
but much more general speckling |
The nest was a simple relined structure inside the old Yellow-throated nest which looked old as the leaves in the structure were dried and deteriorating.
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| The clutch was in an old Yellow-throated Scrubwren nest |
The nest was set about head height, c 190cm, and typical of a Yellow-throated Scrubwren in being suspended from a the end of a thin branch over an open patch of forest floor -in this case a footpath, although often they are hung over stream lines.
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| The nest was suspended over a human track through riverside forest |
