The most common species, which recorded more than a billion in number, are the house sparrow (1.6 billion), which is found in many parts of the world, starlings (1.3 billion), barn swallows (1.1 billion) and ring-gulls (1.2 billion). The latter is similar to our common gull, and it is common in North America.
These scholars Publish their results In the American Scientific Journal PNAS, Arrive at this estimate by combining professional and scientific statistics with so-called citizen science on the website eBird International equivalent of the Dutch Waarneming.nl Bird watchers entered hundreds of millions of views. For example, they developed an algorithm that should estimate the size of populations of nearly all bird species, in part based on the estimated density of those groups. The result of these numbers led researchers to estimate that there are six times more birds in the world than humans.
Researchers have also found that there are relatively few species that occur in large numbers, while a relatively large number of species are rare.
The researchers acknowledge in their publications that their number contains doubts and is not complete. For example, they have inventoryed about 9,700 bird species, about 92 percent of the total number of bird species found. This number is estimated to be around 11k, depending on the taxonomy you use.
They also realize that citizen science is not always accurate. For example, the researchers take into account that bird watchers are primarily concerned with rarity and special sights, which could lead to overrepresentation in this research. Some bird species are also seen or underreported so much that they are also underrepresented in this study.
Researchers believe that the quality and reliability of “citizen science” will only improve in the future, and as a result their future estimates will also gain accuracy.
Evolution, environment and conservation
Scientists say their research could be helpful for basic questions about environment and evolution. Such as the influence of humans on bird populations and the issue of which bird species deserve the most protection. The researchers wrote: “A complete understanding of how and why bird species came to their present population sizes will be of paramount importance for the future study of evolution, ecology and conservation.”
This is not the first time that scientists have attempted to map the number of birds in the world. The results are completely different, which indicates how difficult this can be. In 1997 two British researchers came to Appreciation Between 200 and 400 billion individual birds. Australian researchers attribute this big difference to the use of a different method. British researchers had estimated the population density of all bird species equally, while Australian scientists looked at it separately for each bird species.
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