Mound-building birds on Magnetic Island

Walking up the hill behind Nelly Bay a few weeks ago, following the pipeline to Horseshoe Bay, I was surprised by an enormous mound beside the vehicle track.

megapode mound of leaf litter and earth
Megapode mound, with my hat for scale

My surprise wasn’t at the existence of the mound, but at its size. It was at least six metres wide and over a metre high from where I stood, and obviously higher still on the other side because of the slope of the ground.

It was clearly a Megapode nesting mound and only two species of mound-builders live in North Queensland: Scrub Turkeys (Alectura lathami, aka Brush Turkeys) and Orange-footed Scrubfowl (Megapodius reinwardt). I have often seen the former on Maggie, and Jo Wieneke’s Birds of Magnetic Island confirms that the latter are also common there although I don’t remember seeing one on the island. I’m not surprised, however, since I have often seen them at Pallarenda.

Orange-footed Scrubfowl Megapodius reinwardt
Orange-footed Scrubfowl at Pallarenda
Scrub turkey, Paluma
Scrub Turkey beside the picnic table at Paluma

I know Scrub Turkeys and their nests quite well, and this example was exceptionally big for a turkey mound. I don’t know Orange-footed Scrubfowl as well as I know Scrub Turkeys, mainly (I think) because they are not so comfortable around people and their built environment, and I’m not sure that I have ever seen a nesting mound which I knew to be theirs.

The birds are much smaller than Scrub Turkeys, however, so I vaguely expected their mounds to be smaller, too. I was wrong, though: several references put the size range of the mounds at around 2-4 metres wide and 1 metre high for the bigger bird and up to 9-13 metres by 3-5 metres (!) for the smaller one. Such enormous heaps are not the work of a single season or even necessarily of a single mating pair but they are still very impressive.

I walked high enough up the side of the Nelly Bay mound to see its top, scooped out and disturbed as expected.

megapode mound - leaf litter and dirt
The top of the mound

Which species is responsible for this magnificent construction will remain an open question until someone sees the birds at work but my best guess is that the scrubfowl deserve the honour.

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