Elephant Birds of Madagascar

Elephant birds are extinct, flightless birds belonging to the order Aepyornithiformes, native only to the island of Madagascar. There are three recognized species: one in the genus Mullerornis and two in Aepyornis. Of them, Aepyornis maximus is possibly the largest bird that ever lived, with eggs among the largest known of any amniote (flightless birds). The closest living relatives of elephant birds are kiwis, found only in New Zealand.

Elephant birds were large birds, the largest of which could reach a height of 3 meters in a normal standing position. Like most other flightless birds, they had long legs and elongated necks, with relatively small heads relative to their body size. They had straight, thick, conical beaks. The skulls of elephant bird species differ little from each other, except in size, although the front of the skull in Mulleronis is a bit less robust than in Aepyornis. The wings were rudimentary.

It is generally accepted that the extinction of the elephant bird was the result of human activities. The birds were initially widespread and lived throughout Madagascar. Research from 2021 suggested that elephant birds, along with three species of Madagascan pygmy hippopotamus (Hippopotamus lemerlei, Hippopotamus laloumena and Hippopotamus madagascariensis), became extinct somewhere between 800 and 1050 AD[1]. This timing coincided with major environmental changes in Madagascar caused by humans converting forest to grassland, likely for cattle ranching, with this habitat change likely triggered by burning the forest. This reduction in forest area may have had a knock-on effect, such as elephant birds being more frequently encountered by hunters, although there is little evidence of human hunting of elephant birds. People may, however, have eaten elephant bird eggs.

These birds fed, among other things, on the seeds of the baobab trees (Adansonia spp.). These are large, club-like seeds. When the elefant birds became extinct, it also meant that the baobab trees were in serious trouble. Because the fruits are no longer eaten, the seeds (1.5 centimeters in diameter) were no longer dispersed. Nowadays all seeds fall to the ground close to the mother tree, which does not benefit genetic diversity within populations. These trees now depend on Madagascan fruit bat (Eidolon dupreanum) for fertilization. However, these bats are heavily hunted and are therefore becoming increasingly rare. Reduced pollen exchange leads to increasing genetic isolation between baobab populations.

[1] Hansford et al: Simultaneous extinction of Madagascar's megaherbivores correlates with late Holocene human-caused landscape transformation in Quaternary Science Reviews – 2021. See here.