A group of researchers have successfully completed one of the biggest data studies of its kind ever conducted, with the lofty goal of counting how many wild birds inhabit Earth.
Their final figure was calculated by combining over one billion sightings by some 600,000 birdwatching contributors logged on the citizen science portal eBird, with additional scientific case studies.
The combined data set was then fed into a scaling algorithm which can accurately extrapolate a tally, based on the figures provided for roughly 9,700 bird species.
The researchers found there is a rough total of just over 50 billion wild birds on the planet, or more than six times the human population.
“Humans have spent a great deal of effort counting the members of our own species – all 7.8 billion of us,” says ecologist Will Cornwell, from the University of New South Wales (UNSW) in Sydney, Australia. “This is the first comprehensive effort to count a suite of other species.”
Some four species of wild bird were classified in the so-called ‘billionaire club’: the house sparrow, the European starling, the barn swallow and the ring-billed gull.
Meanwhile, roughly 12% of bird species are estimated to have a worldwide population of less than 5,000.
The scientists hope the method will take off and become more commonplace, allowing researchers to more effectively monitor multiple animal species with whom we share our planet.
They do, however, admit to a certain, inevitable degree of uncertainty in the numbers, owing to birdwatchers seeking out certain species more than others, migratory patterns among certain types of birds and a variety of additional, complicating factors.
Instead, the final rough figure is a median average from estimates generated over the course of the study. The actual mean average is 428 billion.
In future, the scientists are hoping to repeat the research every few years to provide an even more accurate bird count, while helping conservation efforts via population-change monitoring.
“By properly counting what’s out there, we learn what species might be vulnerable and can track how these patterns change over time – in other words, we can better understand our baselines,” says biologist Corey Callaghan, from the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig in Germany.
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