While it seems like I already know a bit about prehistoric life, before each of these blog articles I make sure to do my research on the animal that I aim to talk about, as any blog writer should do regardless of their subject area. During my research I not only broaden my knowledge, but also gain an extra appreciation for the animal in question. In the case of todays subject, Aepyornis (Greek for “high bird”), more commonly known as the “Elephant Bird”, my research showed just how little I actually knew about it. Aepyornis was a much more fascinating animal than I had realised (not just “a big ostrich”), and in this blog I aim to put the spotlight on this underrated animal.
For starters there wasn’t just one “Elephant Bird”; there was a whole family of them! “Elephant Bird” is the common name given to a family of flightless, bipedal, ostrich-like herbivorous birds from Madagascar known as the Aepyornithae. The “Elephant Bird” name originates from tales of the “Roc”; a legendary giant bird spoken of by Arab traders and written about by the famous explorers Marco Polo (13th century) and Ibn Battuta (14th century). It was also one of the monsters that the adventurer Sinbad encountered in “The Arabian Nights” tales (first published in the 18th century). It was said to be so big that it could carry an elephant in its talons. Polo in all likelihood based his Roc description on accounts of large, lemur hunting Malagasy Crowned Eagles that lived on Madagascar until the 16th century. However reports from other travellers of massive eggs, which belonged to Aepyornis, became associated with the Roc, and so the Aepyornithae family became collectively known as “Elephant Birds”. The Aepyornithae belonged to a larger order of birds known as the Ratites. This is the same group that contains ostriches, emus and cassowaries. You may think that since the Elephant Birds lived on Madagascar their closest relatives would be African ostriches since Madagascar lies off the East African coast. However this is not the case. Their closest living relatives are actually kiwis; small flightless birds which have long, thin beaks, reduced eyesight and are also ratites. Kiwis live only on New Zealand, which is 7,000 miles east of Madagascar! So how are these two birds so closely related despite living so far apart? Well the theory is that around 60 million years ago the common ancestor of kiwi’s and Elephant Birds still possessed flight and flew to these two separate islands, establishing colonies. Then, over millions of years, the two islands drifted further apart from each other (out of flying range) and the two separated populations both evolved flightlessness, independently of one another.
Another result of living on an isolated island for much of their evolution, and with no large mammalian herbivores to compete with, is that the Elephant Birds could grow to massive sizes. Aepyornis was no different and was thought to have been the largest bird that ever lived until relatively recently. Originally it was believed that Aepyornis maximus could grow to heights of more than 3 metres and weigh up to 800kg. However a study in 2018 by Hansford & Turney showed that there were enough skeletal differences between these largest specimens and other Aepyornis for these large Aepyornis to be re-classified as a new member of the Aepyornithae family (alongside Aepyornis and another Elephant Bird named Mullerornis). It was given the rather striking name of Vorombe titan, which is a combination of Malagasy and Greek and translates to “big bird” (Vorombe = Malagasy for bird, titan = Greek for big). As a result the size estimates of Aepyornis is now considered to be a more modest 2.5 metres tall and 400-500kg in weight on average, which is still larger than any living bird! Another of Aepyornis’ (and other Elephant Birds’) claims to fame is their humongous eggs. At their biggest they measured 34cm long, had a circumference of a metre and weighed 15 kilos. That’s 150 times bigger than a chicken egg, larger than any dinosaur egg and the largest eggs of any animal ever. Imagine the fried egg you would get from that! It wouldn’t just be enough for your breakfast; it would be enough to feed your entire family for the whole day! Such huge eggs would have meant that Elephant Bird chicks would have been more highly developed compared to other birds and the lack of any large egg thieves (before humans arrived) meant that it would have been safer for Elephant Birds to lay these eggs.
Aepyornis held the ecological niche of “large herbivore” on Madagascar. Its diet consisted of fruit, grasses and leaves and Aepyornis used its strong neck and overall size to reach them, before biting off and swallowing chunks with its beak. Unlike a lot of other large herbivores recent research has suggested that Aepyornis was a mostly nocturnal animal. The evidence comes from another 2018 study (by Torres & Clarke) where Aepyornis braincases were examined with a CT scanner. This produced a 3D model that the researchers could manipulate and examine in detail. Using this they discovered that Aepyornis had enhanced olfactory lobes (the part of the brain that processes smells) and reduced optic lobes (the part of the brain that processes vision). This is a similar, albeit less extreme, version of the brain structure of kiwis; which are nocturnal birds with limited vision and a reliance on smell to sense their environment. Furthermore Torres & Clarke also showed that different Aepyornis species had slightly different sensory lobes. You see there are two recognised species of Aepyornis; Aepyornis maximus (the larger, forest dwelling one) and Aepyornis hildebranti (the smaller, plains dwelling one). In A.maximus the olfactory lobes were proportionally larger, and the optic lobes proportionally smaller, than in A.hildebranti. This is presumably because A.maximus lived in dense rainforests, where eyesight is less useful due to the dense trees, while A.hildebranti lived in the open plains where the lack of dense trees meant they could see greater distances.
Aepyornis shared its Madagascan home with a menagerie of recognisable animals still alive today, such as Ring-tailed lemurs, Fossas and Chameleons. However it also lived alongside some strange animals that are no longer around. These included Archaeoindris, a giant lemur that was the size of a Silverback gorilla, the aforementioned Malagasy crowned eagle which modern lemurs still possess an innate fear of even though it is now extinct, and giant tortoises similar in size and lifestyle to the modern day Galapagos giant tortoise. So once upon a time Madagascar had an even greater diversity of life than it does now. However there are no Elephant Birds, giant lemurs, huge tortoises or giant eagles anymore. This is thought to have been mainly due to change in climate, which lead to changes in food availability. The actions of humans are also commonly linked to the disappearance of many Madagascan animals. However they may not have played as big of a role as previously thought. Yet another 2018 study (2018 should be renamed “Year of the Elephant Bird” due to all the studies carried out that year!) dated Elephant Bird bones that showed distinctive cut marks made by human tools to 10,500 years ago, the end of the Pleistocene period and start of the Holocene period. This was a whole 8,000 years earlier than humans had previously been thought to have reached Madagascar. Since Aepyornis and other Elephant Birds became extinct sometime between the 10th-12th Centuries (though sightings had been reported to as late as the 17th century) this means that humans co-existed with the birds for longer than previously thought. So they couldn’t have quickly hunted them to extinction as had been previously assumed. However this doesn’t mean that Aepyornis wasn’t a target for humans or that human activity wouldn’t have affected their numbers. For one the sheer size of both the animal and especially its eggs (which could be quickly poached from Aepyornis nests) would have been an attractive prospect for human hunters. For another humans were converting the Madagascan forests and plains into farmland, destroying Aepyornis’ habitat, and domesticated chickens and guinea fowl brought to Madagascar may have passed on bird related diseases to Aepyornis, which it had no immunity to.
So overall, Aepyornis was a truly splendid animal, with a much more varied and detailed history and lifestyle than at first glance. The Elephant Birds are reminiscent of a time 65 million years ago when the close relatives of birds ruled the world. The dinosaurs were long gone, but in this little corner of the world Aepyornis and its family carried on their legacy.
Christopher R. Torres and Julia A. Clarke 2018, Nocturnal giants: evolution of the sensory ecology in elephant birds and other palaeognaths inferred from digital brain reconstructions, Proc. R. Soc. B.28520181540, http://doi.org/10.1098/rspb.2018.1540
James P. Hansford and Samuel T. Turvey 2018, Unexpected diversity within the extinct elephant birds (Aves: Aepyornithidae) and a new identity for the world’s largest bird, R. Soc. open sci.5181295, http://doi.org/10.1098/rsos.181295
James Hansford, Patricia C. Wright, Armand Rasoamiaramanana, Ventura R. Pérez, Laurie R. Godfrey, David Errickson, Tim Thompson, Samuel T. Turvey. Early Holocene human presence in Madagascar evidenced by exploitation of avian megafauna. Science Advances, 2018; 4 (9): eaat6925 DOI: 10.1126/sciadv.aat6925
“Strike from the Sky”, Mythic Creatures Exhibition, American Museum of Natural History, https://www.amnh.org/exhibitions/mythic-creatures/air/strike-from-the-sky
Katz, Bridget, “Giant, Intact Egg of the Extinct Elephant Bird Found in Buffalo Museum”, Smithsonian Magazine, April 23rd, 2018, https://www.smithsonianmag.com/smart-news/giant-intact-egg-extinct-elephant-bird-found-buffalo-museum-180968850/
Bolton, M., Houston, D., & Monaghan, P. (1992). Nutritional Constraints on Egg Formation in the Lesser Black-Backed Gull: An Experimental Study. Journal of Animal Ecology, 61(3), 521-532. doi:10.2307/5607