The findings are drawn from the most complete and detailed picture of bird diversity yet made, based on a new global database of all living bird species. The map also shows that the pattern of bird diversity is much more complicated than previously thought.

The researchers conclude that different types of 'hotspot' - the most bird-rich locations on the planet -- do not share the same geographic distribution, a finding with deep implications in both ecology and conservation.

For birds, hotspots of species richness are the mountains of South America and Africa, whereas hotspots of extinction risk are on the islands of Madagascar, New Zealand and the Philippines.

"In the past people thought that all types of biodiversity showed the same sort of pattern, but that was based on small-scale analyses," says senior author Professor Ian Owens of Imperial College London. "Our new global analyses show that different sorts of diversity occur in very different places."

Biodiversity hotspots have a high profile in conservation, but are controversial as their underlying assumptions remain untested. The key assumption is that areas 'hot' for one aspect of diversity will also be hot for other aspects.

Their analyses now show that surprisingly, this is not the case - different types of hotspot are in fact located in different areas.

"Different types of diversity don't map in the same way," Prof Owens says. "There is no single explanation for the patterns. Different mechanisms are therefore responsible for different aspects of biodiversity, and this points to the need to base conservation strategy on the use of more than one measure of biodiversity."

The team mapped three different measures of diversity for the study: species richness, threatened species richness (as assessed by their extinction risk), and endemic species richness (birds with a small breeding range). Only the Andes in South America contains bird hotspots under all three measures.

To understand the mechanisms behind large scale biodiversity patterns, the researchers first had to construct global maps before delving into them.

Biodiversity hotspots According to Conservation International, the world's biodiversity hotspots hold especially high numbers of endemic species despite their limited extent: combined, the total area of remaining habitat covers only 2.3 percent of the Earth's land surface. Each hotspot faces extreme threats and has already lost at least 70 percent of its original natural vegetation. Over 50 percent of the world's plant species and 42 percent of all terrestrial vertebrate species are endemic to the 34 biodiversity hotspots. source: Conservation International

"The prior bits of work were horribly dispersed: in paper maps on expert's desks, or in very old books and the heads of aging experts who had originally surveyed the areas," said Professor Owens.

It took five person years to get the data into a digital mapping format known as a 'GIS system'. This database was then used to score the presence or absence of each of the nearly 10,000 different bird species in a grid covering the world's land area. Each of the 20,000 cells in the grid is 100 km squared and contains an area similar to that of Cyprus.

"We hope that birds are a model for this type of work," said Professor Owens. "There is such a wealth of historical information about them. They are also large, colourful and you can see them in the day time. It's very difficult to do at this scale for other organisms."

Andean Condor (Vultur gryphus)

The study is the result of a new form of ecological funding - a Natural Environment Research Council Consortium Grant. These grants encourage large-scale work and this was the first to be awarded, shared between Imperial College London, the Institute of Zoology, and the Universities of Sheffield and Birmingham. The next stages of the consortium work, following the mapping, are to develop ecological and evolutionary explanations for the bird diversity.

Notes to Editors:

This research is published in Nature (18 August 2005).

Title: Global hotspots of species richness are not congruent with endemism or threat

Authors: C. David L. Orme1, Richard G. Davies3, Malcolm Burgess1, Felix Eigenbrod1, Nicola Pickup1, Valerie A. Olson4, Andrea J. Webster5, Tzung-Su Ding6, Pamela C. Rasmussen7, Robert S. Ridgely8, Ali J. Stattersfield9, Peter M. Bennett4, Tim M. Blackburn5, Kevin J. Gaston3 and Ian P. F. Owens1,2

1 Division of Biology

2 NERC Centre for Population Biology, Imperial College London, Silwood Park, Ascot, Berkshire SL5 7PY, UK

3 Biodiversity and Macroecology Group, Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK

4 Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK

5 School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

6 School of Forestry and Resource Conservation, National Taiwan University, 1, Sec 4, Roosevelt Road, Taipei 106, Taiwan

7 Michigan State University Museum and Department of Zoology, West Circle Drive, East Lansing, Michigan 48824-1045, USA

8 Academy of Natural Sciences, 1,900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania 19103, USA

9 BirdLife International, Wellbrook Court, Girton, Girton Road, Cambridge, CB3 0NA, UK

About Imperial College London
Consistently rated in the top three UK university institutions, Imperial College London is a world leading science-based university whose reputation for excellence in teaching and research attracts students (11,000) and staff (6,000) of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and management and delivers practical solutions that enhance the quality of life and the environment - underpinned by a dynamic enterprise culture. Website: www.imperial.ac.uk





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