there is a new approach to find out if bird species are threatened. Usually, a bird is classified as endangered or
critically endangered on the basis of its range size--the minimum space a species needs to survive. Range size in birds is among the several criteria
used by the World Conservation Union (iucn) to determine the threat level.
Researchers from the Duke University have recently come up with a new model to determine the range size. According to the new model, the actual area available to a bird is much smaller than estimated. For example, the iucn estimated Brazil's grey winged cotinga's (Tijuca condita's) range to be 3,350 sq km but the new model estimates it at 155 sq km only. Researchers say the model may change the threat status attached to birds.
Using their threshold range size, the researchers re-analyzed the status of 158 species classified as non-threatened and 74 species classified as threatened by iucn. They found 18 species, not currently classified as threatened, should be labelled threatened. Twenty species classified as threatened could be removed from the category, the study shows. But, the researchers do not dispute that iucn considers other population factors to present a more comprehensive picture.
Researchers, however, insist that their's is a better method to calculate range-size than the one iucn is using. Susanne Shultz of the University of Liverpool's Population and Evolutionary Biology Research Group says this model will help assign threat categories faster. Experts also point out that such a model will help provide better information for conservation and land use.
The study was published in the online edition of Conservation Biology.
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