AEPYORNITHIDS PREDATORS

[darren.naish@port.ac.uk]

On the possible predators of _Aepyornis_, Chip (aka 
Vorompatra.. which for those of you who don't know is a 
Malagasy word, ostensibly, for _Aepyornis_) wrote...
 
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AFAIK, until the Malagasy got there, the croc was the only 
thing that would have been a predatory threat to an adult 
_Aepyornis_. As to how much plumage they had on their 
legs: almost everything we know about Aepyornid 
appearance is based on skeletal remains.
----------------------

Madagascar had a few large predators until very recently, 
though it's doubtful that any of these would conceivably 
have tackled an adult aepyornithid. 

Besides _Crocodylus niloticus_ there was _'Crocodylus' 
robustus_, a 'horned' crocodyline most closely related to 
_Osteolaemus_, the west African dwarf crocodile (Brochu 
& Storrs 1995). _Osteolaemus_ spends more time on land 
than many other crocodylians and is somewhat altirostral (= 
tall snouted). I've handled _robustus_ material and don't 
recall it being notably more altirostral than, say, _C. 
niloticus_ and, as for whether _robustus_ was more 
terrestrial than large living crocodylines, I have no idea. A 
crocodile of its size (total length comparable with average 
_C. niloticus_ and weight estimated at 170kg by Burness et 
al. (2001)) could perhaps catch and drown a bird the size of 
_Aepyornis_. Given that Chris has worked on this taxon he 
may have further comments...

Secondly, there was _Stephanoaetus maharey_, a giant 
eagle closely related to the extant African crowned eagle 
_S. coronatus_ but somewhat bigger (Goodman 1994). _S. 
maharey_ may have been extant as recently as 500 years 
ago and has been suggested as the origin of the roc legend. 
Like its extant relative, _S. maharey_ probably preyed 
predominantly on medium-sized mammals and it's well 
known that lemurs still exhibit a fear of big raptors even 
though none are present on Madagascar today (there are 
plenty of smaller raptors though). The living crowned eagle 
is phenomenally powerful and notoriously aggressive. Giant 
eagles elsewhere in the world (notably _Harpagornis 
moorei_ of New Zealand, which weighed c. 13kg) have 
been capable of killing flightless birds of upwards of 200kg, 
plus extant _Aquila_ (max weight 6kg) can kill domestic 
animals weighing 150kg, thus it's conceivable (but unlikely 
given that extant crowned eagles are not bird-killers) that 
_S. maharey_ could kill an aepyornithid.

Thirdly, Pleistocene Madagascar was also home to a fossa, 
_Cryptoprocta spelea_, which was not much over 25% 
bigger than the extant species, _C. ferox_. However, extant 
fossas only weigh 7-12kg and Burness et al. (2001) estimate 
_C. spelea_ at a meagre maximum of 17kg, making the 
traditional characterisation of it as a 'giant fossa' somewhat 
misleading. It's not certain that _C. spelea_ is specifically 
distinct from _C. ferox_ and I think it's doubtful that this 
lithe animal could have preyed on big birds, especially those 
weighing more than 150kg. Like the extant species it was 
probably a proficient climber that hunted lemurs.

Refs -- 

Brochu, C. A. & Storrs, G. W. 1995. The giant dwarf 
crocodile: a reappraisal of _?Crocodylus? robustus_ from 
the Quaternary of Madagascar. In Patterson, Goodman & 
Sedlock (eds) _Environmental Change in Madagascar_, p. 
70 (abs).

Burness, G. P., Diamond, J. & Flannery, T. 2001. 
Dinosaurs, dragons, and dwarfs: the evolution of maximal 
body size. _Proceedings of the National Academy of 
Sciences_ 98, 14518-14523.

Goodman, S. M., 1994. Description of a new species of 
subfossil eagle from Madagascar: _Stephanoaetus_ (Aves: 
Falconiformes) from the deposits of Ampasambazima. 
_Procedings of the Biological Society_ 107, 421-428.

-- 
Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045