Earth is home to around 50 billion wild birds according to a new global estimate, but most species are very rare and only a handful number in the billions.
Just four undomesticated species are in the club of those with a billion-plus individuals, with house sparrows (Passer domesticus) the most abundant, followed by European starlings (Sturnus vulgaris), ring-billed gulls (Larus delawarensis) and barn swallows (Hirundo rustica). By contrast, 1180 species number fewer than 5000 birds each.
The estimate of around six wild birds for every human on the planet is the first since researchers arrived at a global figure of 200 to 400 billion undomesticated birds 24 years ago. The big gap between the studies isn’t due to a dramatic decline in bird numbers, but is explained by a more sophisticated method that used data for more species.
Experts say we could improve bird conservation with further research on why some species are rare, whether it is just because they have evolved to occupy a single island or because of human activities such as deforestation.
Photo: House sparrows/©ptici.info