*Extinct*
The Pile-builder Megapodes (Megapodius molistructor) is an extinct species of megapode. The fossil remains were found by Jean-Christophe Balouet and Storrs L. Olson in caves in New Caledonia and Tonga. For more information, see our guide on breeding.
Description
With a weight of 3.5 kg, Megapodius molistructor was heavier than all existing megapodes. In Tonga, it was the largest ground-dwelling bird species. The fossil material consists of a left tarsometatarsus, a complete left scapula, a half right scapula, a proximal end left ulna, a fragment of the right femur, several ungual phalanxes, an anterior end right scapula, a proximal end right ulna, a distal half left ulna, a distal end left ulna proximal and a half right femur.
Extinction
When the early settlers of the Lapita culture arrived in Tonga at about 1500 BC, they found only marine species like sea turtles and giant forms of terrestrial birds like megapodes, doves, and rails. The hunting of these bird species for food led to their rapid extinction. In New Caledonia, the giant megapode might have survived into historic times. William Anderson, a naturalist and surgeon’s mate at the HMS Resolution during James Cook’s second South Sea voyage, described a bird from New Caledonia with bare legs which he named Tetrao australis. Considering that all Tetrao species have feathered legs, Anderson’s bird might well have been a megapode.
References
- Steadman, David William (2006): Extinction and Biogeography of Tropical Pacific Birds. University of Chicago Press. ISBN 0-226-77142-3
- Balouet, Jean Christophe; Olson, Storrs L.: Fossil Birds from Late Quaternary Deposits in New Caledonia PDF, online
- Balouet, J.-C. & Alibert, E. (1990): Extinct Species of the World, Barrons, New York, London, Toronto, Sydney. ISBN 2-7373-0254-4
Habitat and Distribution
Megapodius Molistructor was found in at least two major island groups of the southwest Pacific, namely New Caledonia and Tonga. Fossils have been found in limestone cavern systems. These caves are often used as natural traps to preserve the remains of long-lost species.
The birds would have thrived in areas with volcanic ash and sandy soil. This choice of habitat is consistent with the behaviour of modern megapode, which prefer warm, well-drained substrates to build their nesting mounds.
Tonga was home to the largest bird that lives on the ground. It provided abundant food, nesting areas, and relative protection from predators until human colonisation disturbed this balance. New Caledonia’s presence seems to have lasted longer, which suggests that the island’s greater size and isolation might have provided some temporary refuge.
Breeding and Nesting
Megapodes have a unique method of incubation. Megapodes, unlike most birds that incubate eggs with body heat, bury their eggs in mounds made of decomposing plants or warm sand and rely on heat sources for hatching.
Although no nests have been directly found by the Pile-Builder Megapode, it is reasonable to assume that, based upon the physiology of its closely related megapodes and their habits, they followed the mound nesting strategy. The name of the species, Molistructor, roughly translates as “mound builder”, which supports this assumption.
Megapodes build mounds up to several meters in diameter. They carefully regulate temperature by adding and removing materials. The Pile-Builder Megapode, given its size, likely built substantial nesting mops that could be up to 1,5 meters tall.
The eggs would be incubated for several weeks if they were buried deep in the compost piles. The chicks are fully feathered, independent and capable of flying within hours after hatching. The precocial development of the chicks meant that no parental care was needed. This is a rare trait in birds, and it allowed megapodes to focus their energy on mound maintenance.
Diet and Feeding
Like its modern relatives, the Pile-Builder Megapode was likely an omnivorous that ate primarily what the forest floor offered. The diet of the Pile-Builder Megapode would have included bugs, seeds, berries and fallen fruit. It may have dug up tubers and roots due to its large beak.
Strong feet and claws allowed it to scratch leaf litter and uncover beetle larvae and worms. It may have eaten crabs or other small creatures in coastal habitats.
Combining a diverse diet with adaptable foraging techniques would have made Pile-Builder Megapodeana an eco generalist, a role which often confers resilience to changing environments. Even this adaptability could not protect it from human pressures.
Vocalizations
Although no recordings of Megapodius molybdaenus exist, for obvious reasons, modern Megapodius provide some insight into the likely vocal behaviour. Existing species communicate in dense underbrush using low-pitched calls, grunts and hissing noises. According to iNaturalist, this species is well documented.
The calls are used to defend territories, locate mates or coordinate mound activity. Males can also make warning calls to scare off predators or rivals. Similar vocal patterns would have been part of the behaviour repertoire of the extinct Megapode due to its likely social and territorial structure. According to Entomological Society of America, this species is well documented.
The absence of predators on Pacific Islands before the arrival of humans may have enabled the birds to become more vocal and use vocalisations with greater frequency than other species that are constantly threatened. These calls became a liability after the arrival of humans and other invasive species such as rats and cats.
Conservation and Extinction
This story is sadly familiar in island ecosystems. This species, like the Dodo in Mauritius and the Moa in New Zealand, fell victim to the perfect hurricane of threats that came with colonisation
Around 1500 BC, the Lapita, early Austronesian explorers, settled in Tonga. They brought fire and domesticated animals with them, as well as new hunting practices. Inadvertently, they introduced invasive animals like rats and pigs – creatures that destroyed the nests of birds such as the megapode.
A reliable source of food, Megapodius Molistructor quickly became a large bird with fewer flight restrictions and a predictable nesting site. The meat and eggs of this bird would have been very valuable to early settlers.
The species could have survived in New Caledonia for a much longer time and possibly into historical times. If William Anderson’s late 18th-century report truly described a megapode in existence, the extinction of this species has occurred within the last 250 years.
Conclusion
The Pile-Builder Megapode, though extinct now, offers a poignant reminder of the fragility of island ecosystems. The fossilised bones found in caves and the notes left by 18th-century explorers are all traces of a lost world.
Today, many megapodes are endangered. They have been impacted by the same factors that decimated Megapodius Molistructor. Conservationists in places such as Indonesia, Australia and the Philippines work to safeguard remaining populations. This ensures that lessons from the past do not repeat themselves.
It may be long gone, but the Pile-Builder Megapode’s story serves as a powerful reminder that human actions are interconnected with ecological balance. We can pay tribute to its memory through study, reflection and preservation. This will hopefully ensure a better future for the remaining megapodes.
External links
- Steadman, David William: The biogeography and extinction of megapodes in Oceania (PDF, full text)
- Association Endemia – Megapodius molistructor
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