Threatened species occur world-wide

John Clarkson Many globally threatened species (such as the Bristle-thighed Curlew) are restricted to small islands Zoom In

Biodiversity is under threat across the world. Threatened landbirds are particularly concentrated in the tropics, notably in Brazil and Indonesia. Threatened seabirds are found throughout the world’s seas, but especially in the southern oceans.

Most countries support threatened species

Nearly all countries and territories in the world (92%) support populations of one or more Globally Threatened Bird species (GTBs). Many GTBs (63%) have small ranges and are restricted to single countries. Others have ranges that are shared by many states, nearly 100 in the case of Lesser Kestrel (see pdf case study, box 1). Threatened species are found both across the largest land-masses and on some of the smallest islands. For example, the entire global population of the threatened Ascension Frigatebird breeds on Boatswainbird Islet, a 1 km2 flattopped rock off Ascension Island in the Atlantic Ocean. Oceanic islands have disproportionately large numbers of GTBs because their bird species are particularly susceptible to human influence owing to their isolated evolutionary history (box 2). The open oceans are critically important for marine GTBs, with particularly high densities in the international waters of the southern oceans, notably around New Zealand (box 3).

Tropical countries are particularly important

Although GTBs are found from polar regions to the equator, they are concentrated in the tropics. Regions such as the tropical Andes, the Atlantic Forest of Brazil and the archipelagos of South-East Asia particularly stand out. Certain countries have exceptional numbers of GTBs. Indonesia and Brazil support the largest number of any country or territory (119 and 117 species respectively) and also the highest totals of GTBs endemic to a single country. In addition, they support the most GTBs relative to total numbers of bird species, and some of the highest numbers of threatened mammal and plant species (box 4).

Boxes: case studies and scientific analyses

Download SOWB pp.18–19 (PDF, 380 KB) containing the following:

1. GTBs are distributed across the world
Density map of GTBs across the world

2. Many GTBs are restricted to small islands
Number of GTBs on continents and islands

3. The southern oceans are important for marine GTBs
Density map of threatened seabirds in the southern ocean

4. Some countries are particularly important for GTBs
i). The countries with the highest numbers of GTBs
ii). Countries with the most threatened avifauna