Elephant Bird

2008/9 Schools Wikipedia Selection. Related subjects: Birds

Elephant birds
Conservation status
Extinct  (16th century)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Aves Superorder: Paleognathae Order: Struthioniformes Family: †Aepyornithidae Bonaparte, 1853
Genera
†Aepyornis †Mullerornis

Elephant birds are an extinct family of flightless birds comprising the genera Aepyornis and Mullerornis.

Dimensions

The elephant birds, which were giant ratites native to Madagascar, have been extinct since at least the 16th century. Aepyornis was the world's largest bird, believed to have been over three meters (10 feet) tall and weighing close to half a ton (454 kilograms, or 1,000 pounds), although it was exceeded in skull size (28 inches) by an unclassified Phorusrhacoid unearthed in October 2006. Remains of Aepyornis adults and eggs have been found; in some cases the eggs have a circumference of over one meter (three feet) and a length up to 34 cm (Mlíkovsky, 2003). The egg volume is about 160 times greater than a chicken egg (Hawkins and Goodman, 2003: 1026).

Species diversity

Four species are usually accepted in the genus Aepyornis today; A. hildebrandti, A. gracilis, A. medius and A. maximus (Brodkorb, 1963), but the validity of some is disputed, with numerous authors treating them all in just one species, A. maximus. Up to four species are also generally included in Mullerornis (see below; Hawkins and Goodman, 2003: 1029). Because there is no rainforest fossil record in Madagascar, it is not known for certain if as likely there were species adapted to dense forest dwelling, just like the cassowary in Australia and New Guinea today. However, some rainforest fruits with thick, highly sculptured endocarps, such as that of the currently undispersed and highly threatened forest coconut palm Voanioala gerardii may have been adapted for passage through ratite guts, and the fruit of some palm species are indeed dark bluish purple (e.g. Ravenea louvelii and Satranala decussilvae), just like many cassowary-dispersed fruits (Dransfield and Beentje, 1995: 21, 63, 112).

Biogeography

Like the cassowary, ostrich, rhea, emu and kiwi, Mullerornis and Aepyornis were ratites; they could not fly, and their breast bones had no keel. Because Madagascar and Africa separated too long ago for the ratite lineage (see Yoder and Nowak, 2006), Aepyornis had been thought to have dispersed and become flightless and gigantic in situ (van Tuinen et al., 1998); but a landbridge from elsewhere in Gondwana to Madagascar for the elephant bird - ostrich lineage was probably available around 85 million years ago (Hay et al. 1999). However, subfossil Aepyornis fragments have not yet been successfully sequenced for mitochondrial DNA (Cooper et al. 2001).

Supposed remains of "aepyornithid" eggs found on the eastern Canary Islands represent a major biogeographical enigma. These islands were probably not connected to mainland Africa when elephant birds could have occurred there. During episodes of very low sea levels, there may have been a land bridge, and at least for some time, there probably was an archipelago between Fuerteventura/ Lanzarote and the African coast. This would have enabled flightless birds to cross over to these islands by chance. Still, there is no indication that elephant birds evolved outside Madagascar, and today, the Canary Island eggshells are considered to belong to extinct North African birds that may or may not have been ratites ( Eremopezus/ Psammornis), or even Pelagornithidae, prehistoric seabirds of immense size.

Extinction

It is often believed that the extinction of the Aepyornis was an effect of human actions. However, the birds were probably not only elusive but widespread, occurring from the northern to the southern tip of the island (Hawkins and Goodman, 2003: 1028), yet their eggs were vulnerable. A recent archaeological study found remains of eggshells among the remains of human fires (see Pearson and Godden 2002: 124), suggesting that the eggs regularly provided meals for entire families, but it is not known if there were taboos ("fady") against the killing of adult birds, although there is indeed evidence that they were killed. Animals arriving with the human colonists, such as rats and dogs, may also have preyed upon the eggs of the ratite population and reduced their viability.

When they finally died out is also not certain; tales of these giant birds may have persisted for centuries in folk memory. There is archaeological evidence of Aepyornis from a radiocarbon-dated bone at 1880 +/- 70 BP (= c. 120 AD) with signs of butchering, and on the basis of radiocarbon dating of shells, about 1000 BP (= c. 1000 AD) (see discussion and references in Hawkins and Goodman, 2003: 1029). A perhaps more plausible alternative to the theory that humans hunted the elephant birds to extinction in a very short time for such a large landmass (the blitzkrieg hypothesis) is the possible secondary effect of human impact by possible transfer of hyperdiseases from human commensals such as chickens and guineafowl. The bones of these domesticated fowl have been found in subfossil sites in the island (MacPhee and Marx, 1997: 188), such as Ambolisatra (Madagascar), where Mullerornis sp. and Aepyornis maximus have been reported (Goodman and Rakotozafy, 1997). Also reported by these authors, ratite remains have also been found in W-SW Madagascar, at Belo-sur-Mer (A. medius, Mullerornis rudis), Bemafandry (M. agilis) and Lamboharana (Mullerornis sp.). A third viable theory to explain the demise of the giant elephant birds (as apparently first pointed by Attenborough (1961: 43)) is climate change, related to an increased drying of Madagascar during the Holocene (to which the impact of humans might have been additive).

Name

English name

Aepyornis maximus is commonly known as the 'elephant bird', a term that apparently originated from Marco Polo's account of the rukh in 1298, although he was apparently referring to an eagle-like bird strong enough to "seize an elephant with its talons" (Pearson and Godden, 2002: 121). Sightings of eggs of elephant birds by early sailors (e.g. text on the Fra Mauro map of 1467-69, if not attributable to ostriches) could also have been erroneously attributed to a giant raptor from Madagascar. The legend of the roc could also have originated from sightings of such a giant subfossil eagle related to the African Crowned Eagle, which has been described in the genus Stephanoaetus from Madagascar (Goodman, 1994), like it large enough to carry off large primates; today, lemurs still retain a fear of aerial predators.

Malagasy name

The ancient Malagasy name for the bird is Vorompatra, meaning "bird of the Ampatres". The Ampatres are today known as the Androy region of southern Madagascar (Pearson and Godden, 2002: 139) . Indeed, Étienne de Flacourt wrote (1658), "vouropatra - a large bird which haunts the Ampatres and lays eggs like the ostriches; so that the people of these places may not take it, it seeks the most lonely places". .

Eggs

Occasionally the subfossilized eggs are found intact. The National Geographic Society in Washington holds a specimen of an Aepyornis egg which was given to Luis Marden in 1967 . The specimen is intact and contains an embryonic skeleton of the unborn bird. A cast of the 'Aepyornis' egg is preserved at the Grant Museum of Zoology at London University, and has been adopted by Claudia, the niece of the author and illustrator Charlotte Cory. The BBC television personality David Attenborough owns an almost complete fossilized eggshell, which he pieced together from fragments he himself had found in Madagascar.

Elephant Bird Species

Genus Aepyornis

• Aepyornis gracilis Monnier, 1913
• Aepyornis hildebrandti Burckhardt, 1893

=Aepyornis mulleri Milne-Edwards & Grandidier , 1894

• Aepyornis maximus I. Geoffroy-Saint-Hilaire, 1851

=Aepyornis modestus Milne-Edwards & Grandidier, 1869

=Aepyornis ingens Milne-Edwards & Grandidier, 1894

=Aepyornis titan Andrews, 1894

• Aepyornis medius Milne-Edwards & Grandidier, 1866

=Aepyornis grandidieri Rowley, 1867

=Aepyornis cursor Milne-Edwards & Grandidier, 1894

=Aepyornis lentus Milne-Edwards & Grandidier, 1894

Genus Mullerornis

• Mullerornis betsilei Milne-Edwards & Grandidier, 1894
• Mullerornis grandis Lamberton, 1934
• Mullerornis agilis Milne-Edwards & Grandidier, 1894
• Mullerornis rudis Milne-Edwards & Grandidier, 1894

=Flacourtia rudis Andrews, 1894

In literature

• H.G. Wells wrote a short story entitled Aepyornis Island about the bird. It was published in The Complete Short Stories of H.G. Wells ( ISBN 0-7538-0872-2). Full text.