World is home to 50bn birds, ‘breakthrough’ citizen science research estimates

University of NSW study suggests six times as many individual birds as humans but that many species are very rare

There are about 50 billion individual birds in the world, according to new research that uses citizen science observations to try to estimate population numbers for almost 10,000 species.

The paper, led by scientists at the University of New South Wales, suggests there are about six times as many birds on the planet as humans - but that many individual species are very rare.