Following are key findings of the annual "Red List" report, issued during an International Union for Conservation of Nature congress in Barcelona from Oct. 5-14:

There are 5,487 species of mammals in the world. Of the 4,651 species for which enough data is available, 1,139 or one in four are in danger of extinction. At least 76 mammals have gone extinct since 1500. The last survey of mammals was in 1996 and findings and categories are not directly comparable.

188 mammals are in the worst category before extinction, or "critically endangered". Twenty-nine of these may already be extinct, such as the baiji or Yangtze dolphin in China.

One in two mammal species are declining in number. Threats have worsened for species such as the Tasmanian Devil, an Australian marsupial, the Caspian seal or the fishing cat, found in Asia.

Main threats are loss of habitat and hunting by humans. Other risks include climate change and disease.

Some species are recovering. China's Pere David deer is extinct in the wild but captive populations have risen and could lead to re-introduction in the wild. The African elephant has been moved to "near threatened", a lesser level of risk than its previous category as "vulnerable" because of rising numbers.

Species' ranges vary from a few hundred square meters for the Bramble Cay melomys, an Australian rat, to all the world's oceans for the orca or killer whale. Most land species occupy an area smaller than Britain.

Worldwide, the Red List comprises 44,838 species, of which 16,928 are considered threatened, or 38 percent. Groups such as amphibians are far worse off than mammals.