Vanished Without a Trace? What Happened to the Egg-Burying Bird From the Hobbit’s Cave?

Yesterday I did one of my favourite things: watched a David Attenborough documentary. The series Our Planet followed animals from the freezing Arctic to the hot, humid jungles of South America. More than once, the documentary would show off a plethora of birds. From penguins whose ancestors strayed too far from home and ended up in the Galápagos to birds of paradise that tried to woo potential partners with fancy footwork and flashy feathers. One bird group not featured, but one that would have been an interesting sight, was the megapodes.

Megapodes are ground-dwelling, chicken-like birds that bury their eggs in the ground. Around 20 species exist, many of which are found in Australasia, specifically in Wallacea. Despite the number of living megapodes there, no fossil had ever been recovered.

Until now. A new study describes the discovery of the first fossil megapode in Wallacea, a brand new extinct species that lived on the island of Flores. The same island was once home to Homo floresiensis, sometimes called the 'hobbit'. How old was it, where exactly was it found, and what can it tell us about these ancient ground-dwelling birds?

Eggs in the Ground

Megapodes are birds that don't build nests. Well, not traditional nests, anyway. Instead, they bury their eggs in the ground and rely on environmental heat and composting vegetation to incubate them. Most of these birds live east of Wallace's Line in the Philippines, eastern Indonesia, Australia, and Melanesia. But they are absent from mainland Southeast Asia and larger western Indonesian islands.

DNA studies suggest megapodes split from other fowl-like birds during the Late Cretaceous, with the burrow-building group, which includes Megapodius, likely forming in Wallacea before spreading across the islands over the last 2 million years.

Despite this group likely originating in Wallacea, no megapode fossils have been found there. To be fair, bird fossils in general are rare in Wallacea.

On the island of Flores, where our fossil megapode would eventually be found, only one megapode species currently lives. The Orange-footed scrubfowl.

But then excavations in the Liang Bua cave on Flores, the same cave known for Homo floresiensis, yielded a single partial leg bone. It belonged to a bird, and closer examination revealed it was a megapode.

A New Megapode

The fossil was recovered in 2009. At the time, Indonesian researcher Rokus Due Awe (1942–2015), the same man who first identified the bones of Homo floresiensis, identified the bone as a bird. It came from the oldest deposits, Unit 1A, dated to around 190,000 to 120,000 years ago.

To identify the fossil, researchers compared it with skeletons at the Smithsonian's National Museum of Natural History in Washington, DC. These covered nine living species of megapode, including the Australian brushturkey, the maleo, and the Malleefowl. Notably, they could not compare it to the Orange-footed scrubfowl, as the Smithsonian had no specimens of this species. For extinct species, like Megapodius alimentum and Megapodius amissus, they turned to published descriptions and photographs.

The fossil differed from any other known megapode. Its toe joints differed in shape and position, and its size suggests it would have been among the largest megapodes ever known. Based on size estimates, this megapode would have weighed around 3.9 kg, making it far larger than the living orange-footed scrubfowl, which weighs just 0.5-1.2 kg. Its leg bone was much longer and sturdier than even the largest living and extinct species from Fiji and Tonga.

All the evidence suggested this was a new species. The researchers named it Megapodius rokusi after Rokus Due Awe, who spent decades excavating at Liang Bua and was the first to identify the bone as avian. This makes M. rokusi the first megapode species named after an Indonesian researcher.

The Many Uncertainties of the First Extinct Megapode of Wallacea

Based on a single bone, we can say little about how it lived or why it went extinct. Without wing bones, we don't know whether it could fly. Most megapodes are strong fliers, but the large extinct Megapodius amissus and Megapodius alimentum are thought to have been flightless, so it could go either way.

It isn't even certain that this bird built burrows. Despite belonging to the "burrow-building" group, not all megapodes do. Whether they use burrows depends on the environment. The orange-footed scrubfowl builds mounds. It builds most of them on sandy or loamy soil in open forest with little shade (probably to keep temperatures in the mound nice and cosy). The mounds are a mix of soil and decomposing organic matter, warmed by the sun and the heat of decay. Females lay an egg in these mounds every few days, cover it with leaf litter, then say 'Sayonara' to it before going on their merry way, though both parents keep tending the mound. When the young chick hatches, it stays in the mound's cavity for a day or two before digging itself out and flying away.

Orange-footed scrubfowl still live near Liang Bua today, and M. rokusi may have done the same. During the Pleistocene, open grasslands with patches of dense forest surrounded the cave. This environment would have been suitable for M. rokusi to nest, with the forested patches providing cover for new hatchlings.

Why it went extinct is another question. Megapode eggs are yolk-rich (50-60% yolk), so megapode eggs would have been an easy food source for Homo floresiensis and, later, modern humans. In fact, multiple megapode extinctions are thought to have been caused by humans. No wonder, considering all one has to do is dig up unguarded, not-exactly-discreetly hidden eggs.

M. rokusi may have existed until around 60,000 years ago, only to vanish alongside Liang Bua's other extinct animals, like the giant stork, the dwarf Stegodon, Homo floresiensis and vultures. On the other hand, it may have died out earlier or outlived all of these species. However, there is no evidence either way.

It may have lived alongside the orange-footed scrubfowl, though megapode species rarely live in the same place unless they breed or use habitat differently. That, along with signs the scrubfowl spread fairly recently, could indicate the orange-footed scrubfowl only arrived on Flores after M. rokusi.

So, that leaves many unanswered questions, but that doesn't make M. rokusi boring or worthless. On the contrary, its discovery fills a gap in the fossil record. One that has likely existed for so long not because Wallacea had few megapode species in the past, but because bird fossils of any kind are scarce in the region.

Researchers in the region typically focus on mammalian bones, so birds are left to sit in fossil collections.

On top of that, M. rokusi comes from a stretch of time for which we know next to nothing about birds. So this little fossil helps fill that gap. Like a tiny flickering candlelight in a dark cavern.

M. rokusi is a reminder that the faunal diversity we see today is but a tiny piece of the ancient biodiversity that once thrived here. Somewhere in that past, a nearly 4 kg megapode may have lived, possibly digging holes into mounds and leaving chicks to fend for themselves.

Perhaps one day we will know more about this mysterious creature, perhaps even enough to warrant a feature narrated by David Attenborough. I can almost imagine it now.

"And here we see the magnificent M. rokusi carefully digging a hole in a mound of soil and rotting leaves, which will incubate her precious egg. But she is not the only one interested in this mound, for a Komodo dragon has been watching, and an egg this rich in yolk is a prize few can resist…"

What do you think caused M. rokusi's extinction? And had you ever heard of megapodes before?

Let me know what you think, and if you'd like to support this blog and the person writing it, you can chip in once, monthly, or yearly. Only if you'd like to.

References

Cardenas Gomez, K., Rose, A., Gibb, K. S., & Christian, K. A. (2022). Microbial communities associated with mounds of the Orange-footed scrubfowl Megapodius reinwardt. PeerJ, 10, e13600. https://doi.org/10.7717/peerj.13600

Meijer, H. J. M., Sutikna, T., Saptomo, E. W., & Tocheri, M. W. (2026). A new species of megapode (Galliformes: Megapodiidae) from the Pleistocene of Liang Bua, Flores. Alcheringa: An Australasian Journal of Palaeontology, 1–12. https://doi.org/10.1080/03115518.2026.2741158