a) The countries with the highest numbers of threatened birds

Analysis of IUCN Red List 2016 data

Regional and national variations in numbers of threatened birds depend on a combination of evolutionary history (which influences species diversity, range size, behaviour, and ecology) and the past and present threats that these species face. Certain countries, mainly in the tropics, have particularly high numbers of threatened species and are therefore priorities for international conservation action. Ten countries have more than 75 globally threatened birds, with Brazil, Indonesia, and Colombia heading the list with 170, 158, and 126 respectively (Figure a). These countries also rank highly for numbers of threatened mammal species (Hilton-Taylor 2000). Furthermore, they support a particularly high number of threatened endemic birds (those restricted to breeding in a single country): Brazil has 97, Indonesia has 102, and Colombia has 50. A particularly high proportion of threatened birds found in the Philippines are endemic: 76.5%. With dependent territories included, France ranks fifth in the list of countries with the most threatened birds, supporting 109.

b) The countries with the most threatened birds (labelled) compared to the countries with greatest bird biodiversity

Analysis of IUCN Red List 2016 data

The overall avifaunas of some countries are particularly threatened. A graph of the number of threatened species plotted against the total number of bird species for each country shows that numerous countries are situated well above the regression line, i.e. they support more threatened species than expected (figure b, BirdLife International 2008). The ten countries with the most threatened birds include seven of the most important in terms of absolute numbers of threatened birds (e.g. Brazil, Colombia, and Peru). The analysis also highlights several territories that have highly threatened birds despite relatively low total avian diversity. For example, French Polynesia supports 109 bird species, of which 33 are globally threatened, and Norfolk Island (to Australia) supports 44 species, of which 11 are globally threatened. Some countries also hold far fewer threatened species than expected, i.e. they fall far below the regression line. These include very small countries or territories with no globally threatened birds (currently Monaco, Saint Barthélemy an overseas territory of France, and San Marino), but also larger ones such as the Sudan (2.5% of bird species threatened) and Honduras (1.7% threatened), both with more than 700 species of birds. Fortunately, few bird species are yet threatened in these countries because they still hold vast tracts of largely unpopulated forest.