Monday, August 9, 2010

Red List Indices to measure the sustainability of species use and impacts of invasive alien species

After habitat loss and degradation, the leading threats to biodiversity are over-exploitation and invasive alien species. For birds, newly synthesised data using the standard classification schemes for utilisation and threat types for the IUCN Red List allow novel analyses on the importance of these threats and permit the calculation of Red List Indices (RLIs) to show trends in the status of birds driven by these factors.

Evidence of utilisation by humans was found for a total of 4,561 bird species, representing 45.7% of the world’s 9,990 extant and extinct bird species. Among these, two purposes of use dominate:

· 3,649 species (37.0% of extant species, 87.4% of utilised species) were recorded as being used as pets, and

· 1,398 species (14.2% of extant species; 33.5% of utilised species) were recorded as being hunted for food.

Less significant uses include sport hunting, wearing apparel or ornamentation and traditional medicine , with small numbers of species being recorded as used for handicrafts, fuel (from oil or fat, principally from seabirds) and household goods (e.g. down for mattresses), etc. Many species are used in more than one way; for example, 68.9% of species that are hunted for food are also kept as pets.

Much of this use drives trade at an international scale, involving at least 3,337 species, mostly for the pet trade. RLIs show that although successful control and management of use and trade have led to some species improving in status, this has been outweighed by the number of species deteriorating in status owing to unsustainable exploitation. Overall, the RLI showing trends in extinction risk driven by issues related to use shows a negative slope: human use of birds is currently unsustainable. Similarly, and of relevance to the Convention on the International Trade in Endangered Species (CITES), the RLI for internationally traded bird species showing trends in extinction risk driven by issues related to international trade is also declining: international trade remains a threat to the world’s birds.

Invasive species impact at least one third of the world’s threatened bird species (398 species, 32.6%), with mammals being the most important (impacting 81.1%), particularly through predation by carnivores and rodents. The RLI illustrating impacts of invasive species shows that they are driving deterioration in the status of the world’s birds. RLIs for the impacts of use and invasive species will be important indicators to help track progress towards the target of significantly reducing biodiversity loss by 2010.

This article is written by Stuart H.M Butchrtfull and published by the Bird Conservation International.