Species are becoming more threatened

National Avian Research Centre Houbaras have deteriotated in status faster in some regions than others Zoom In

The Red List Index for birds shows that the world’s birds have become more threatened since 1988, with more species slipping closer to extinction. Seabirds and Asian forest birds have shown particularly severe declines. We cannot yet determine global trends for other groups of organisms in this way, but similar declines are expected.

Birds provide unique information for assessing global biodiversity trends

The threat status of all of the world’s birds has been comprehensively assessed four times between 1988 and 2004, using the categories and criteria of the IUCN Red List. By examining the number of species moving between Red List categories as a result of genuine improvement or deterioration, it has been possible to develop Red List Indices which quantify the overall change in threat status of the world’s birds over the last 16 years (see pdf case study, box 1). This information is unique: for no other group of organisms can we yet chart global trends in this way.

More species are slipping closer to extinction

Despite the conservation efforts of governments and non-governmental organisations across the world, birds as a group are becoming more threatened (see box 1, figure a). Some species have improved in status during 1988–2004, but many more have deteriorated. More species are slipping closer to extinction, as shown by the Red List Index for Critically Endangered birds, although there has been a recent levelling out in the rate of deterioration (box 1, figure b). Species that do not move between categories on the IUCN Red List for genuine reasons (and therefore do not affect the index) are not necessarily stable. For the period 2000–2004, nearly half of threatened species (45% of 859) were judged by species experts to have deteriorated in terms of population or range size (box 2).

Trends in some regions and habitats are of particular concern

Deterioration in the threat status of the world’s birds has not occurred evenly across the world. A regional breakdown of the Red List Index shows that Asia’s birds have undergone the sharpest declines since 1988. This is largely due to the rapid forest destruction in the lowlands of Borneo and Sumatra through the 1990s (box 3). However, Red List Indices for species characteristic of different habitats how that, at a global level, birds in all major natural habitats are suffering (box 4). Comparisons of different species-groups highlight the particularly dramatic declines in the threat status of seabirds, linked with the recent expansion of commercial longline fisheries (box 5) in addition to pressures at nesting colonies. Trends for other groups of organisms cannot yet be quantified in a similar way, but they are likely to mirror the deterioration shown by birds.

Boxes: case studies and scientific analyses

Download SOWB pp.16–17 (PDF, 315 KB) containing the following:

1. The world's birds are getting more threatened
Red List index based on numbers in categories from 1988–2004

2. Most threatened birds are deteriorating in status
Percentages in categories whose status is better/same/worse from expert assessment

3. Birds have deteriorated in status faster in some regions than others
Red List Indices for birds in different regions

4. Birds have deteriorated in status across all major habitat types
Red List Indices for birds in different habitats

5. Seabirds have deteriorated dramatically compared to other groups
Seabirds have deteriorated severely since the first global assessment of all birds in 1998