Maori crow
| Maori crow | ||||||||||||
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| Corvus antipodum | ||||||||||||
| ( Forbes , 1893) |
The Maori crow or New Zealand crow ( Corvus antipodum ) is an extinct species of corvids (Corvidae). It was one of the largest members of the genus of ravens and crows ( Corvus ) and was characterized by an elongated, relatively straight beak and long legs. The Maori crow came to the North and South IslandNew Zealand before. It was probably a bird of the open and semi-open landscape and possibly had the sea coast as its habitat. The body structure and location of the remains, along with the original geography of New Zealand, suggest that the Maori crow displayed opportunistic feeding behavior.
The subfossils of the species were discovered in the late 19th century and described in 1893 by Henry Ogg Forbes , who then placed them in the genus " Palaeocorax ", which also included the Chatham raven ( C. moriorum ). Later authors concluded that both species were typical Corvus crows . They probably came from a settlement by an Australian species, probably the New Holland crow ( C. coronoides ), which took place at the latest in the Pleistocene . The Maori crow was found in New Zealand in two subspecies , separated from each other by the Cook Strait . It survived until the early days of the Māori colonization of New Zealand and died out before the arrival of the Europeans.
features
The Maori crow was a very large species of crow and, with the exception of the Chatham raven ( C. moriorum ), was larger than all of today's Australasian crows. The fossil material of the species is numerous, but often only preserved in fragments, which is why conclusions about the appearance are not always possible. The beak was long, broad and relatively straight. It was slightly smaller than the Chatham Island raven, but it was still one of the largest species in the Corvus genus . The weight of the Maori crow is estimated at 0.9–1.0 kg, which would have made it about as heavy as an African vulture raven ( C. albicollis ). The ratio of wing length to leg length was slightly smaller than that of the crow species living today. This suggests that the Maori crow was at least slightly adapted to an environment without ground predators , although it retained its ability to fly. This development was not as pronounced as in the Chatham raven. There were clear differences in body size between the North and South Islands: Maori crows were larger in the south than in the north. The barrel bones found on the South Island measure an average of 71 mm, whereas on the North Island it is only 68 mm. Similar relationships apply to the other parts of the skeleton. The variation ran clinically from the warmer north to the colder south, which corresponds to Bergmann's rule . In the Pleistocene , the birds were on average the same size as in the Holocene , but showed a greater variance .
distribution and habitat
The Maori crow was native to the North and South Islands of New Zealand. The fossil record shows a noticeable difference between the Pleistocene and Holocene : While the species is found in fossil deposits north and south of the Cook Strait in the Pleistocene , it is absent in deposits on the North Island in the Holocene. However, it was found there in archaeological sites from the early Maori period. For the Pleistocene, the finds are concentrated on the west coast and the eastern tip of the North Island. With the exception of the southwestern South Island, the Maori crow is also passed down from the east coast of the Holocene.
All sites are distributed along the coast of the New Zealand islands, so far no bones have been found in deposits further inland. This suggests that the Maori crow was a coastal inhabitant. The fact that most of the finds dated to the Holocene come from the poorly forested east coast of New Zealand suggests open landscapes or forest edges as a habitat.
Way of life
The way of life of the Maori crow is likely to have corresponded to that of the recent large crows. As an unspecialized coastal inhabitant, it presumably ate an omnivorous diet on fruits, large insects , terrestrial vertebrates and the eggs and young from seabird colonies . Richard Holdaway also suspects that the Maori crow also ate on carcasses of the Haastadler ( Harpagornis moorei ) birds and believes it is possible that it was chasing moa chicks . It is also possible that the species combed the mudflats at low tide . The Maori crow's physique does not suggest any particular adaptation, even if its relatively long legs made it a reasonable runner. According to Holdaway, the nest was likely built out of sticks and placed in tree tops or rock alcoves. Brian Gill contradicts this , with his presumption that the Maori crow was a ground-breeder or at least brooded at a low altitude, since their extinction could not be explained otherwise.
Systematics and history of development
Taxonomy
The first remains of the Maori crow were found in the 19th century. Henry Ogg Forbes initially thought the larger bones from the South Island were remnants of the Chatham raven . In 1893, however, he described the significantly smaller bones of the North Island as a separate species Palaeocorax antipodum and placed them near the Chatham raven. The specific epithet antipodum probably refers to New Zealand as the antipode of Europe. Forbes did not give a holotype , which later turned out to be problematic. As with many other species described by Forbes, later authors could not understand which bones he had used for his descriptions, which questioned the validity of the taxon Corvus antipodum . William Pycraft , who examined the Chatham raven, doubted the legitimacy of an independent genus " Palaeocorax " in view of the osteological characteristics . Pierce Brodkorb finally synonymized it with Corvus and declared the Maori crow to be a subspecies of the Chatham raven. Brian Gill subjected bones from the North Island, the South Island and Chatham to a detailed comparison in 2003 and came to the conclusion that Chatham and the main islands each had their own species. He put the smaller northern and the larger southern form in their own subspecies and assigned both a lectotype . In order to clearly differentiate the two taxa from the Chatham raven, he selected particularly small specimens as types.
External system
Due to the great distance to the next larger land masses, only a few species of crows come into question for the colonization of New Zealand, which could be the closest relatives of the Maori crows. It is certain that it is closely related to the Chatham raven ( C. moriorum ) and has a direct common ancestor with it. The fact that two different species developed on Chatham and the main islands can also be observed in some of the other endemics of New Zealand. Australian crow species on the one hand and the New Caledonian straight-billed crow ( C. moneduloides ) on the other hand are suitable for the colonization of the islands . Brian Gill considers the New Holland crow ( C. coronoides ) from southwest Australia to be the closest living relative of the Maori crow because it is the closest in body size to all neighboring species.
Internal system
Analogous to some other New Zealand bird species, Gill created two subspecies for the Maori crow to take into account the size difference between the North and South Islands.
- Corvus antipodum antipodum ( Forbes, 1893 ):
- Nominate form , North Island. Smaller shape.
- Corvus antipodum pycrafti Gill , 2003 :
- South island. Larger form, the specific epithet honors William Pycraft for his services to the study of the Maori crow.
die out
The exact time when the Maori crow became extinct is unknown. What is certain is that it disappeared in the course of the first settlement of New Zealand by the Māori . The exact reasons are unclear: As an unspecialized, airworthy omnivore, the Maori crow actually had a good chance of surviving. It is possible, however, that Pacific rats ( Rattus exulans ) and other animals introduced by the Māori severely affected the clutches of the species; provided the Maori crow was a ground breeder . Another cause of the species' disappearance may have been the habitat changes that accompanied the early development of New Zealand. Since it occurs just as often in prehistoric cooking areas as in fossil sites of the same age, overhunting is unlikely to be the reason for its extinction.
Sources and References
literature
- Pierce Brodkorb: Catalog of Fossil Birds. In: Bulletin of the Florida State Museum. Biological sciences. 23 (3), 1978. pp. 139-157. ( Full text )
- Henry Ogg Forbes: Aphanapteryx and Other Remains in the Chatham Islands . In: Nature 46 (1185), 1892. doi : 10.1038 / 046252a0 , pp. 252-253.
- Henry Ogg Forbes: A List of the Birds Inhabiting the Chatham Islands. In: Ibis 5, 1893. pp. 521-546. ( Full text )
- Brian J. Gill: Osteometry and Systematics of the Extinct New Zealand Ravens (Aves: Corvidae: Corvus). In: Journal of Systematic Palaeontology 1 (1), 2003. doi : 10.1017 / s1477201903001019 , pp. 43-58.
- Richard N. Holdaway: New Zealand's Pre-human Avifauna and its Vulnerability . In: New Zealand Journal of Ecology 12, 1989. pp. 11-25.
- Julian Pender Hume, Michael Walters: Extinct Birds. A&C Black, London 2012. ISBN 140815725X .
- William Pane Pycraft: On the Skeleton of Palaeocorax moriorum . In: Novitates Zoologicae 18 (1), 1911. pp. 123-128. ( Full text )
- Trevor H. Worthy , Richard N. Holdaway: The Lost World of the Moa. Prehistoric Life of New Zealand. Indiana University Press, Bloomington 2002, ISBN 0-253-34034-9 , pp. 336-355.
Web links
- New Zealand Raven. Corvus antipodum. by Paul Martinson. Illustration from the book Extinct Birds of New Zealand by Alan Tennyson, Te Papa Press, Wellington, 2006
Individual evidence
- ↑ a b c Forbes 1893 , p. 544.
- ↑ a b Holdaway 1989 , p. 17.
- ↑ Gill 2003 , pp. 47-50.
- ↑ Gill 2003 , pp. 45-46.
- ↑ Gill 2003 , p. 46.
- ^ Worthy & Holdaway 2002 , p. 439.
- ↑ a b c d Gill 2003 , p. 55.
- ↑ Pycraft 1911 , p. 128.
- ↑ Brodkorb 1978 , p. 160.
- ↑ Gill 2003 , pp. 53-54.
- ↑ Gill 2003 , p. 54.
- ↑ a b Hume & Walters 2012 , p. 245.