Many species are close to extinction

Jon Riley The Caerulean Paradise-flycatcher has a total range size of just 2 km² on the island of Sangihe, Indonesia Zoom In

Over 12% of bird species are considered globally threatened, because they have small and declining populations and/or small ranges. In total, 179 bird species are now Critically Endangered and face an extremely high risk of extinction in the immediate future.

One in eight of the world's birds faces extinction

A significant proportion of the world’s biodiversity now faces extinction. It is not yet possible to quantify exactly how many species are at risk, because we have not even named about 90% of all species on Earth, let alone assessed their status. However, a few groups of organisms are well known, and their threat status has been comprehensively assessed using the criteria of the IUCN Red List. These criteria are the most scientifically objective, comprehensive and internationally recognised system yet devised for assessing extinction risk. Using them, all the world’s birds have been regularly assessed by BirdLife International since the 1980s. The 2004 assessment concluded that 1,211 bird species (12% of the total, or one in eight) are globally threatened with extinction. Of these, 179 species are Critically Endangered, meaning that they face an extremely high risk of extinction in the immediate future (see box 1).

All taxonomic groups are under threat

Although birds are still by far the best-known group, the conservation status of four other groups have now been completely assessed for the first time. The proportion of species threatened with extinction in 2003 was found to be about 23% for mammals, 52% for cycads and 25% for conifers. Partial assessments for some other groups also show substantial proportions of the assessed species to be threatened with extinction: c.30% for amphibians, 4–62% for reptiles, 3–49% for fish and 0.2–58% for invertebrates. In most taxonomic groups, it is likely that significant proportions of species are threatened with extinction by the intensifying human impacts on the planet.

Threatened species have small and declining populations and ranges

Most Globally Threatened Birds (GTBs) are threatened because they have small populations. There are 966 species (80% of GTBs) with populations of fewer than 10,000 mature individuals, and 80% of these are also declining (box 2). Even numerous and widespread birds may be threatened owing to rapidly declining populations. In total, 412 GTBs (38% of the total) have populations that are estimated to be declining at rates of at least 30% in ten years or three generations (box 3). Small range size is also an important factor in raising extinction risk. Altogether, 555 GTBs (46%) qualify as threatened because they have ranges that are smaller than 20,000 km², declining and fragmented or restricted to a few locations, with 647 (53%) restricted to ten or fewer locations, and 182 (15%) known only from a single site (box 4).

Boxes: case studies and scientific analyses

Download SOWB pp.14–15 (PDF, 319 KB) containing the following:

1. One in eight of the world's birds are threatened with extinction
In total 1,211 bird species are threatened with global extinction. 179 bird species are classified as Critically Endangered.

2. Most GTBs have small populations
Population sizes of Globally Threatened Birds (GTBs)

3. Most GTBs are declining, some catastrophically
Population trends of GTBs

4. Most GTBs have small ranges
Range sizes of GTBs