The alliance of citizen science combined with big data analyzes by artificial intelligence has recently made it possible to estimate the entire global bird population. Results: there would be around fifty billion, representing more than 9,700 species.
There are about six times as many birds on Earth as there are humans. Some number in the billions, others in the millions, while others are only a handful. “Humans have put a lot of effort into counting the members of our own species – there are all 7.8 billion of us.”, recalls Will Cornwell, an ecologist at UNSW Science and co-author of the study. “We present here the first global effort to count a series of other species”.
Citizen science and algorithm
As part of this work, Cornwell and his team collected nearly a billion bird sightings recorded by more than 600,000 citizen scientists between 2010 and 2019 sure eBird, an online database. Based on this data, the researchers then developed an algorithm to estimate the actual global population of each bird species.
The dataset includes records for almost all species currently living on Earth (92%). However, the authors estimate that the representatives of the remaining 8%, obviously very rare, are unlikely to have much of an impact on the overall estimate.
Out of this sample, only four species belong to the “billion club”: the house sparrow (1.6 billion), the common starling (1.3 billion), the ring-billed gull (1.2 billion) and the Barn swallow (1.1 billion).
Real support for conservation
Conversely, around 12% of the bird species considered in the study have an estimated global population of less than 5000 individuals. Among them are the Chinese Crested Tern, the Rock Ptarmigan, and the Wallace’s Rail.
For these birds, this type of study could be crucial. “Quantifying the abundance of a species is a first essential step in conservation ”, underlines Cornwell. “By properly counting what is out there, we learn which species might be vulnerable and can track how those patterns change over time. So we will be able to tell how these species are doing by repeating the study in five or ten years ”.
While the researchers are confident in his estimates, they recognize that a certain degree of uncertainty is inevitable when operating with such large data.
However, these results, while approximate in some areas, represent the most comprehensive data to date for many species. New information will be regularly added to eBird through citizen observations. The researchers plan to repeat their analysis as more data becomes available.
You will find the details of this work in the Proceedings of the National Academy of Sciences.