Scientists Determine How Many Wild Birds Populate The Planet And… It's A Lot

The world has six birds for every human.

Scientists have accomplished an incredible feat. Thanks to one of the biggest data studies of its kind, researchers have managed to put a number on how many wild birds inhabit the planet.

Care to venture a guess?

Diverse Bird Species
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According to a study by UNSW Sydney, there are roughly 50 billion individual birds in the world. That's approximately six birds for every human on the planet.

"Humans have spent a great deal of effort counting the members of our own species—all 7.8 billion of us," Associate Professor Will Cornwell, an ecologist at UNSW Science and co-senior author of the study, said in a news release. "This is the first comprehensive effort to count a suite of other species."

The number was reached with help of 600,000 "citizen scientists," who contributed a billion observations to The Cornell Lab of Ornithology's eBird database between 2010 and 2019. Using this data, researchers developed an algorithm to estimate the actual global population of each bird species.

The data included 9,700 bird species, which represents about 92% of all living bird species. Because they didn't go out and count every bird, researchers stress that the 50 billion is just an estimate.

"Our findings, while rough in some areas, represent the best-available data we currently have for many species," co-author Shinichi Nakagawa, a UNSW ecologist and statistician, noted.

Interestingly, only four bird species belonged to what researchers are calling "the billion club": species with a global population of over a billion. These include the House Sparrow (1.6 billion), the European Starling (1.3 billion), the Ring-billed Gull (1.2 billion) and Barn Swallow (1.1 billion).

The researchers hope to get more people using eBird and to repeat the study every few years.

"Birding is a hobby that just keeps on giving," said study lead author Dr. Corey Callaghan.

"We will need to repeat and refine this effort to really keep tabs on biodiversity—especially as human-caused changes to the world continue and intensify," he added.

Eyes to the skies!

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  1. Callaghan CT, Nakagawa S, Cornwell WK. Global abundance estimates for 9,700 bird speciesProc Natl Acad Sci USA. 2021;118(21):e2023170118. doi:10.1073/pnas.2023170118

  2. EurekAlert! From Avocet to Zebra Finch: big data study finds more than 50 billion birds in the world.

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