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Darwin's Finches: Genetic research shows that white-eyes evolve faster than any other bird
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The discovery of a new bird to science in a distant archipelago is providing evidence of how, in the absence of competitors, unique species can evolve rapidly to fill empty niches. But the archipelago is not the Galapagos, and the bird is not one of Darwin’s finches.
In the year of the 200th anniversary of Darwin’s birth, a paper in the leading
scientific journal, Ibis, describing a new bird species in the Solomon Islands, has reinforced evidence that white-eyes evolve new species faster than any
other known bird family –including Galapagos finches.
The new species has been named Vanikoro White-eye Zosterops gibbsi. The formal description was published in Ibis by Dr Guy Dutson of Birds Australia
(BirdLife in Australia), who led a recent expedition to the island of Vanikoro to
gather evidence about the bird. Its scientific name gibbsi is in honour of the first person to see the species – David Gibbs.
Vanikoro White-eye differs from other family members by having a distinctively
shaped bill; along with different leg and eye-ring colours.
Vanikoro is a small island in the south-west Pacific, in the Solomon Islands
archipelago. The rugged volcanic island with steep, forest-covered hills was
visited by Jules D’Urville in 1829 – six years prior to The Beagle landing in the
Galapagos - who collected specimens of Vanikoro Flycatcher Myiagra vanikorensis
and Uniform Swiftlet Collocalia vanikorensis.
“Genetic research has shown that white-eyes evolve new species faster than any
known bird family,” said Guy Dutson. “Islands only 3 km apart in the Solomons
have their own white-eye species, and the Solomon Islands alone have 13 species
of white-eye.
“Like Darwin’s finches, these birds have evolved unique beak structures and
feeding behaviours in the absence of competitors”, Dr Dutson added.
White-eyes are small sociable birds of tropical forests. As their common name
implies, many have a conspicuous ring of tiny white feathers around their eyes.
The Vanikoro White-eye differs from the geographically closest white-eye, the
Santa Cruz White-eye Z. sanctaecrucis, by having a longer bill, and different leg
and eye-ring colour.
Vanikoro White-eyes are found in forest habitats, mostly above 350 m, and feed on insects and small fruits. “Vanikoro Whiteeyes were abundant towards the summit of the highest mountain”, noted Dr Dutson, who observed an active nest during his expedition. “Up to three adults fed chicks at a single nest, suggesting cooperative breeding, which has only been documented in two other white-eye species”.
Vanikoro White-eye displaysdifferent feeding behaviours to closely-related birds. “This new species forages in a slower, more methodical manner than
similar white-eyes, suggesting they have evolved into an empty niche”,
commented Dr Dutson.
“Like Galapagos finches, Vanikoro White-eye has evolved perfectly to its
surroundings in the absence of competitors”, said Dr Nigel Collar, the Leventis
Fellow in Conservation Biology at BirdLife International.
“Perhaps the biggest threat to Vanikoro White-eye is introduced alien species
such as rats”, Dr Nigel Collar warned. “Predators introduced by humans now pose
a huge threat to native species across the Pacific.”
“Elsewhere in the Solomon Islands, birds are threatened by logging which can
extend from the coast high into the hills”, added Dr Dutson.
“So little is known about biodiversity in the Solomon Islands”, said Don Stewart –
Director of BirdLife’s Pacific Programme. “Who knows what is still to be found in
the Solomon Islands? We need more expeditions like this throughout Melanesia
before threats such as illegal logging wipe species out before we can help them”.
ENDS
For further details and to arrange and interview, please contact:
Nick Askew, Communications Officer, BirdLife International. Tel: +44 (0)1223
279809; email: nick.askew@birdlife.org.
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Notes for editors:
BirdLife International is a global alliance of conservation organisations working in
more than 100 countries and territories who, together, are the leading authority
on the status of birds, their habitats and the issues and problems affecting them.
A formal description of Vanikoro White-eye was published in leading ornithological
journal Ibis. This taxon will be assessed in due course by the BirdLife taxonomic
working group. If treated as a full species, its conservation status will then be
evaluated by BirdLife, the Red List Authority for birds on the IUCN Red List of
threatened species.
Dr Guy Dutson is a British-born veterinarian, ornithologist and a leader of birding
tours, who is a world authority on the birds of the south-west Pacific region. He
has rediscovered or described several bird species.
Dutson was educated at Cambridge University where he studied veterinary
science. In 1990 he led a Cambridge University expedition to the Solomon Islands
and Papua New Guinea, in the course of which he rediscovered the Superb Pitta
Pitta superba on Manus Island. Further, expeditions to Indonesia and the
Philippines led to the rediscovery of the Tanahjampea Monarch and the Cebu
Flowerpecker Dicaeum quadricolor. In 2003 he rediscovered the Long-legged
Warbler Trichocichla rufa in Fiji.
From 2000 to 2005, based in Fiji, Dutson established and managed the BirdLife
International Pacific program, traveling extensively around the islands of
Melanesia and the south-west Pacific. He now works for Birds Australia (BirdLife
in Australia) as the manager of the Australian Important Bird Areas program.
Dutson wrote most of the Pacific Islands species accounts in the BirdLife
publication ‘Threatened Birds of the World’. He is also involved in editing the
same species for the ‘Handbook of the Birds of the World’.