200 years of kiwi research

While checking a few details on kiwi skeletal anatomy the other day, I discovered some old material I'd written on these strange birds. I've updated it, and here's the first lot of it.

Kiwi have been known to science since 1813. In that year George Shaw (then the Keeper of Zoology at the British Museum), writing in the final volume of his series The Naturalist's Miscellany, described a specimen that had been given to him by Captain Barclay, a privateer engaged in the transport of convicts. Investigation of Barclay's voyages reveal that he probably never visited New Zealand, so he must have obtained the kiwi skin by way of trade. Shaw recognised that the bird was probably related either to struthious birds (ratites) or to gallinaceous ones, and he named it Apteryx australis. This type specimen is now in the Liverpool Museum (its home since 1812). The hand-coloured engraving which accompanied Shaw's description (shown here), made by R. P. Nodder, depicted the bird as standing bolt upright and very tall, much like a penguin. This was the first published representation of a kiwi. Shaw's specimen later proved to be a South Island brown kiwi.

In the following decades, further evidence for the reality of kiwis only occasionally reached Europe. Visiting North Island in 1814-15, J. Nicholas identified kiwi feathers on some Maori cloaks, while in 1824 René Primevère Lesson (1794-1849), a French naturalist travelling on the ship Coquille, obtained a kiwi specimen from North Island and took it back to France. Lesson's specimen has been lost but is thought to have been a piece of skin, and in describing it, Lesson recognised that it came from a bird related to other ratites, though he failed to take note of Shaw's specimen. Lesson named his new specimen Dromiceius novaezelandiae, a name no longer regarded as technically available, and was the first person to introduce the word kiwi to Europe. Though more feather-bearing Maori cloaks were examined in the 1820s, further complete kiwi specimens only began arriving in Europe in the 1830s and 40s. Mostly from North Island, these went to English anatomists like Owen, Bartlett and Mantell. Bartlett, in 1850, was able to show that these North Island specimens differed from Shaw's South Island specimen.

Richard Owen (1804-1892) published a number of papers on kiwi anatomy (Owen 1839, 1840), as well as one paper on kiwi eggs. His project of 1838-9 on the first specimen he obtained took several months to complete and Andrews (1991) suggested that Owen's busy schedule meant that he could not complete this work as quickly as he may have liked. Other workers have also suggested that Owen's hectic academic and social schedule meant that he could not always present all of the data he otherwise planned to (for example, it sems odd that Owen didn't use the complete skeleton of the dinosaur Scelidosaurus as support for his view that dinosaurs were graviportal quadrupeds) (Norman 2000). Owen's busy schedule may explain why he mistook the heart of a platypus for that of a kiwi in one of his published descriptions [image above, from Owen's monograph, borrowed from Ask Dr Vector].

While work on kiwi taxonomy and anatomy continued into the late 19th century, kiwi biology also began to be explored. Thomas Parker (1891) studied the embryological development of kiwi while W. Benham studied both kiwi parasites (as did Chatin and Maskell) and kiwi olfaction. Walter Rothschild (1868-1937), meanwhile, had been collecting a large number of both live and dead kiwi specimens (much as he did with cassowaries), and in 1899 published an account on the group (with a contribution by Frank Beddard) (Rothschild 1899).

20th century work on kiwi

Early in the 20th century, research on kiwi became ever more diverse. During the 1920s and 30s, E. Craigie published important papers on the kiwi brain and how it compared to that of other ratites (Craigie 1929, 1930, 1935). Durward (1932) and other workers published further work on the kiwi brain at this time. The study of kiwi behaviour came into its own as Guthrie-Smith (1914) and Haeusler (1923) published pioneer studies, but little more than 19th century anecdote and the odd observation of a captive bird was on record when it came to kiwi ecology and diet. In the second half of the 20th century, kiwi physiology began to be explored (Farner 1956) and publications also appeared on kiwi husbandry (Lint 1966) and diet (Bull 1959), an area that continued to be investigated in following decades (Watt 1971, Reid et al. 1982, Colbourne & Powlesland 1988).

The 1970s and 80s saw an explosion of research on kiwi ecology, management, husbandry and conservation. Several projects have shown that kiwis are dependent upon certain forested environments and therefore in need of protected habitats. However, a surprising announcement made in 1979 was that kiwis were successfully inhabiting an exotic monoculture of pines, and were thus proving both adaptable and resilient to human impact (see Kleinpaste 1991). Despite the work on kiwi anatomy published in the 19th century by Owen and others, new information on soft part anatomy has still proved forthcoming: in 1973 McCann published a paper on kiwi tongues while in 1979 and 1982 Christopher McGowan (better known for his work on ichthyosaurs!) described the fore- and hindlimb musculature of kiwis. In 1971, Klinsky discussed the paired ovaries of kiwis and in 1968 Wenzel published on the importance of olfaction in kiwis (Wenzel 1968). Research on the abundant parasites of kiwis has continued unabated.

That gigantic egg, and senses, and conservation

Another intensive area of kiwi reseach during the 70s and 80s was the kiwi egg, its physiology and size, and the development of the chick. Such studies could only be initiated now that Hermann Rahn and colleagues had established a new paradigm on the physiology of bird's eggs (see Rahn et al. 1979). In a series of papers on this topic, William Calder was able to show that the huge kiwi egg was not simply a biological oddity, or necessarily a holdover from giant ancestors, but clearly advantageous to a bird living the kiwi's lifestyle (see Calder 1991 for review). Brian Reid was also publishing important work on kiwi egg composition and chick size at the same time (Reid 1971, 1977). Most recently, Mike Dickison has argued that kiwi eggs - which can weigh as much as 20% of the female's weight - are only large because they're single. When compared to the clutches of other ratites, the ratio of kiwi egg : body size is consistent with that of other ratites, it's just that other ratites lay more than 10 eggs per clutch (this research is discussed here but is not yet published) [adjacent x-ray from Ask Dr Vector].

Another interesting piece of recent kiwi research concerns sensory abilities: Martin et al (2007) showed that the small eyes and small visual fields of kiwi, and enhanced abilities to process olfactory and tactile information, makes kiwi extremely atypical among birds (available, free, here). It is well known that, morphologically and behaviourally, kiwi are mammal-like, and in their sensory abilities too they are convergently mammal-like (Martin et al 2007).

A co-ordinated conservation management plan for kiwi was launched in 1991 with the Kiwi Recovery Programme. Studies have shown that kiwi have suffered extensively from predation by introduced mammals, predominantly stoats. As many as 60% of all young kiwi may be killed by such predators, and kiwi taxa are listed variously as 'nationally critical', 'seriously declining', 'gradually declining' and 'range restricted' (Sales 2005). Predator removal, the creation of kiwi sanctuaries, and captive breeding have all been employed in efforts to halt decline. For more on kiwi conservation see Save the Kiwi [adjacent image from wikipedia].

Finally, a very good review of kiwi anatomy, biology and conservation was provided by Sales (2005), and it's available for free here. There's still other kiwi stuff I plan to cover - and at some stage we need to get back to ostriches, and do emus, elephant birds, moa and rheas too. For cassowaries, there's this.

Refs - -

Andrews, J. R. H. 1991. A history of kiwi discovery. In Fuller, E. (ed). Kiwis: A Monograph of the Family Apterygidae. Swan Hill Press (Shrewsbury), pp. 17-34.

Bull, P .C. 1959. Stomach contents of a North Island kiwi (Apteryx australis mantelli) from the Raetihi district. Notornis 8, 143-145.

Calder, W. A. 1991. The kiwi and its egg. In Fuller, E. (ed). Kiwis: A Monograph of the Family Apterygidae. Swan Hill Press (Shrewsbury), pp. 155-171.

Colbourne, R. & Powlesland, R. G. 1988. Diet of the Stewart Island brown kiwi (Apteryx australis lawryi) at Scollay's Flat, southern Stewart Island. New Zealand Journal of Ecology 11, 99-104.

Craigie, E. H. 1929. The cerebral cortex of Apteryx; evidence that the avian neocortex has been reduced from a multilaminar condition. Anatomische Anzeiger 68, 97-105.

- . 1930. Studies on the brain of the kiwi (Apteryx australis). Journal of Comparative Neurology 49, 223-357.

- . 1935 The cerebral hemispheres of the Kiwi and the emu (Apteryx and Dromiceius). Journal of Anatomy 69, 380-393.

Durward, A. 1932. Observations on the cell masses in the cerebral hemispheres of the New Zealand kiwi (Apteryx australis). Journal of Anatomy 66, 437-477.

Farner, D.S. 1956. The body temperatures of the North Island Kiwis. Emu 56, 199-206

Guthrie-Smith, W. H. 1914. Mutton Birds and Other Birds. Whitcombe and Tombs (Wellington).

Haeusler, H. R. 1923. Notes on the habits of the North Island kiwi (Apteryx mantelli). The Emu 22, 175-179.

Herbert, J. & Daugherty, C. H. 2002. Genetic variation, systematics and management of kiwi (Apteryx spp.). Science and Research Internal Report 191, 11-34.

Kleinpaste, R. 1991. Kiwis in a pine forest. In Fuller, E. (ed). Kiwis: A Monograph of the Family Apterygidae. Swan Hill Press (Shrewsbury), pp. 97-138.

Lint, K. C. 1966. Notes on the care and nutrition of Mantell's kiwi at San Diego Zoo. In Jarvis, C. (ed). International Zoo Yearbook 6, 95-96.

Martin, G. R., Wilson, K.-J., Wild, J. M., Parsons, S., Kubke, M. F. & Corfield, J. 2007. Kiwi forego vision in the guidance of their nocturnal activities. PLoS One 2 (2): e198. doi:10.1371/journal.pone.0000198

Norman, D. B. 2000. Professor Richard Owen and the important but neglected dinosaur Scelidosaurus harrisonii. Historical Biology 14, 235-253.

Owen, R. 1839. On the anatomy of the Apteryx. Proceedings of the Zoological Society of London 6, 48-110.

- . 1840. On the anatomy of the Southern Apteryx (Apteryx australis Shaw). Transactions of the Zoological Society of London 2, 257-302.

Parker, T. 1891. Observations on the anatomy and development of the Apteryx. Philosophical Transactions of the Royal Society of London 183 (B), 25-184.

Rahn, H., Ar, A. & Paganelli, C. V. 1979. How bird eggs breathe. Scientific American 240 (2), 46-55.

Reid, B. 1971. Composition of a kiwi egg. Notornis 18, 250-252.

- . 1977. The energy value of the yolk reserve in a North Island brown kiwi chick (Apteryx australis mantelli). Notornis 24, 194-195.

- ., Ordish, R. G. & Harrison, M. 1982. An analysis of the gizzard contents of 50 North Island brown kiwis, Apteryx australis mantelli, and notes on feeding observations. New Zealand Journal of Ecology 5, 76-85.

Rothschild, W. 1899. The genus Apteryx. Novitates Zoologicae 6, 361-402.

Sales, J. 2005. The endagered kiwi: a review. Folia Zoologica 54, 1-20.

Watt, J. C. 1971. The North Island kiwi: a predator of pasture insects. New Zealand Entomology 5, 25-27.

Wenzel, B. M. 1968. Olfactory prowess of the kiwi. Nature 220, 1133-1134.