A glimpse of the past through kakapo poo

Horrocks, M., Salter, J., Braggins, J., Nichol, S., Moorhouse, R., and Elliott, G. 2008. Plant microfossil analysis of coprolites of the critically endangered kakapo (Strigops habroptilus) parrot from New Zealand. Review of Palaeobotany and Palynology, 149:229–245.

This paper was the subject of a recent ecology journal club at Lincoln University. In it, Horrocks et al. (2008) reconstruct the diet of New Zealand's flightless kakapo using coprolites (preserved faeces). Since New Zealand's bird fauna was decimated so recently, there are still faeces to be found in places where their makers are gone. Kakapo were once common throughout New Zealand, but have now been reduced to less than 100 individuals being intensively managed on offshore island reserves. This paper uses traditional methods of identifying plant microfossils (particularly the morphology of pollen and spores) to characterise what kakapo used to eat throughout their mainland New Zealand range. Not surprisingly, the kakapo diet was broader and more varied than what is now available in their offshore island sanctuaries. There are some good tips for what other foods these island birds could be offered.

What is difficult to obtain from this study is what foods were actively sought after by the kakapo rather than which were fed on proportional to their availability in these habitats. Comparing the plant composition of the kakapo faeces with the background levels of pollen and spores at or near these sites (with some undoubtedly tricky adjustments estimating relative plant abundance from pollen and spore counts) could be an interesting follow-on from this study.

The paper can be accessed from ScienceDirect (subscription required).

The ghosts of Pacific avifauna

Diamond, J. 2007. Voices from Bird Bones. Science, 315:941–942. www.sciencemag.org (subscription required).

Jared Diamond reviews two recent publications on the Pacific's many extinct birds.

• "Extinct Birds of New Zealand" by Alan Tennyson and Paul Martinson (Te Papa Press, Wellington, New Zealand, 2006).


• "Extinction and Biogeography of Tropical Pacific Birds" by David W. Steadman (University of Chicago Press, Chicago, 2006).

The review of Tennyson and Martinson's attractive book is brief and complementary. "Martinson's gorgeously detailed paintings bring home the tragic loss of formerly breathing real animals in a way that descriptions of bones cannot achieve" (p. 941). Diamond presents it as a worthy companion to Trevor Worthy and Richard Holdaway's (2002) book, "The Lost World of the Moa".

"The New Zealand fossil avifauna is by far the most completely sampled in the world" (p. 941). Diamond is particularly fascinated by how the extinction of many of New Zealand's endemic birds was followed by a replacement by often related Australian species. He sees there being much to learn about the processes of community assembly from both the Pacific's prehistoric avifauna and the modern bird communities that have replaced them.

David Steadman's decades of excavations have revealed the details of how the Polynesian settlement of the Pacific Islands triggered a mass extinction of birds and other vertebrates. I well remember being stunned when I read Steadman's chapter in the 1997 book "Biodiversity II", with its description of the massive scale of bird extinctions in the Pacific following human arrival. Unfortunately, Diamond's opinion of Steadman's book is less than complementary, not due to any inaccuracies in the data behind the book, but rather regret at the superficial interpretation of this data. In Diamond's eyes, Steadman is stubbornly resistant to the modern analysis of his data and all the amazing things that could be learned from it. With the publication of "Extinction and Biogeography of Tropical Pacific Birds", this modern treatment may follow.

Parakeet inbreedings and hybridisation on the Chatham Islands

Tompkins, D. M., R. A. Mitchell, and D. M. Bryant. 2006. Hybridization increases measures of innate and cell-mediated immunity in an endangered bird species. Journal of Animal Ecology 75:559-564.

This study assessed measures of immune system health in wild populations of hybridizing parakeets on the Chatham Islands, New Zealand. The cosmopolitan red-crowned parakeets recorded had stronger immune systems than the island endemic Forbes' parakeet, consistent with inbreeding. Furthermore, hybrids of the two species had stronger immune systems than pure-bred Forbes' parakeets.

"[A]llowing an enhanced level of hybridization to persist may be the best strategy for ensuring the long-term maintenance of parakeet biodiversity on the Chatham Islands."