First Global Bird Map Shows Complex Diversity Patterns

LONDON, UK, August 19, 2005 (ENS) - The first full map of where the world's birds live shows that the pattern of bird diversity is much more complicated than previously thought. The new 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.

Published in the current issue of the journal "Nature, the map will help to focus conservation efforts, says senior author Professor Ian Owens of Imperial College London.

Cock-of-the-rock in Peru'a Manu National Park (Photo courtesy Orquidea Real Hostal and Tours Cusco Peru)

This is not the case, Owens' team found.

"Different types of diversity don't map in the same way," 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 researchers found 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, but hotspots of extinction risk are on the islands of Madagascar, New Zealand and the Philippines.

Pygmy Kingfisher on the island of Madagascar, a hotspot of extinction risk. (Photo courtesy Peter Bono)

The team mapped three different measures of diversity for the study - species richness, threatened species richness, and endemic species richness.

Species richness is the number of distinct species in a given area, threatened species richness is assessed by their risk of extinction, and endemic, or native, species richness relates to birds with a small breeding range.

Only the Andes mountains of South America contain bird hotspots under all three measures.

To understand the mechanisms behind large scale biodiversity patterns, the researchers first had to construct global maps from scattered resources.

"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 square kilometers and contains an area similar to that of the island of Cyprus.

Professor Ian Owens of Imperial College London (Photo courtesy ICL)

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.

Bird scientists from Taiwan and the United States collaborated with their British colleagues on this project.

Now that the mapping is finished, the next stages of the consortium work are to develop ecological and evolutionary explanations for the bird diversity.