Fossil bird dung shows kakapo dined on parasitic plant
Tuesday 02 Oct 2012
Fossilised bird dung from a cave in the northwest corner of New Zealand's South Island has provided new insights into the lives of two of the country’s most threatened species.
Researchers at Landcare Research and the Department of Conservation in New Zealand, and the University of Adelaide in Australia, made a surprising discovery while analysing the content of fossilised dung (coprolites). One of the coprolites contained abundant pollen of dactylanthus (also known as the wood rose), an endemic New Zealand plant that parasitises the roots of native trees. Ancient DNA and radiocarbon analyses showed that the coprolite had been deposited by a kakapo, a rare flightless parrot, some 250 years before humans first settled New Zealand.
Lead researcher Dr Jamie Wood said the finding was a big surprise.
"This shows that kakapo and potentially many other nectar drinking birds once fed on the nectar of dactylanthus flowers and may also have acted as pollinators or seed dispersers for the plant. It also represents the southernmost record of dactylanthus, and extends the known pre-settlement range of the species by approximately 50 km further south."
Co-author Dr Janet Wilmshurst said dactylanthus is now restricted to an estimated 4% of its pre-human range, occurring in scattered populations concentrated around the central North Island. It is threatened by forest clearance, browsing by introduced mammals – especially possums and ship rats – and illegal collecting of the underground wood roses.
Department of Conservation dactylanthus researcher, and co-author of the study, Dr Avi Holzapfel said the endangered New Zealand lesser short-tailed bat is presently the only known native pollinator of dactylanthus.
“However, we don’t really know the role that rare and extinct fauna once played in the pollination and seed dispersal of plants such as dactylanthus. Analysis of coprolites is one of the only ways that we can detect these broken relationships with a view to one day restoring them".
In the study, published in the journal Conservation Biology, the authors discuss how coprolites can provide a tool for detecting past ecological relationships between species that, due to population declines, no longer co-occur.
Diedre Vercoe, the manager of the Kakapo Recovery Programme, said research on kakapo coprolites can also provide details of kakapo diet in habitats they no longer occur in, but which one day they may be re-introduced into.
“With the transfer of eight kakapo to Hauturu / Little Barrier Island earlier this year, the kakapo and dactylanthus have been re-united. It will be fascinating to see whether this relationship is restored”.
DOC now plans to initiate the use of small cameras to observe if kakapo, or any other nectar drinking birds, do in fact effectively pollinate dactylanthus.
Professor Alan Cooper of the University of Adelaide, a further co-author on the study, said the research had wider implications for species conservation.
“This is an important example of an apparent tight co-evolutionary relationship between threatened endemic species – the plant and the bat – simply representing ‘the last men standing’. The coprolites suggest that kakapo may have served as pollinators, probably along with other species, which is critical for conservation - and reveal the extent of the ecosystem links which have been broken.”