Birds are a ubiquitous presence in our lives, from the chirping sparrows outside our windows to the majestic bald eagles soaring overhead. But how many birds are there in the world? The answer, it turns out, is more complex than you might think.
The consensus among ornithologists is that our planet is currently home to between 9,500 and 11,000 species of birds, making them one of the most abundant types of creatures in the world.
Concerning the size of all bird populations, the most recent estimate — which involved big data analytics and artificial intelligence — pegs the number of individual birds at around 50 billion. About six birds are chirping and flapping their wings for every human. This estimate doesn’t include farmed animals, such as chickens, which numbered nearly 35 billion in 2023.
Birds: a treasure of biodiversity Credit: Hippopx.
According to the International Ornithological Committee, there are an estimated 11,000 different species of birds in the world classified into 44 Orders, 253 Families, and 2,384 Genera. However, most estimates hover at around the 10,000 mark. This incredible diversity is on full display in places like the Amazon rainforest, which is home to over 1,300 species of birds, or nearly 15% of all known bird species.
However, areas outside of tropical regions also have a rich diversity of birds. Numerous bird species can be found in deserts, grasslands, and temperate forests. In fact, scientists have found that surprisingly large numbers of birds, such as penguins, albatrosses, and petrels, can be found in even the most arid regions, like Antarctica.
But the true number of bird species may actually be twice as high as current estimates. Based on the “biological species concept,” which defines a species based on what animals can breed together, scientists and bird watchers use checklists to distinguish between different species. However, George Barrowclough, an associate curator in the Department of Ornithology at the American Museum of Natural History, asserts that this is an antiquated idea that is rarely applied to taxonomy outside of birds.
In 2016, Barrowclough and colleagues at the University of Nebraska and the University of Washington examined a random sample of nearly 200 bird species by their morphological features — physical characteristics like plumage pattern and color, which can be used to highlight birds with separate evolutionary histories. For every type of bird, the researchers identified nearly two distinct species. Based on this analysis, the researchers claim that bird diversity is extremely undercounted, with the true number of bird species hovering at around 18,000. This estimate is corroborated by previous genetic studies of birds, which suggest that the real number of birds could be upwards of 20,000 species.
Had the Biblical Flood story happened today and Noah had been a contemporary taxonomist, things might have turned out very differently. Noah would need to ask God for further clarification when He told him to bring two of each kind of creature into the ark. Specifically, he would need to know “what exactly do you mean by ‘kind’ of creature.” “Are the creatures on your list subspecies? What about different population segments? Is it a biological species or a phylogenetic species?”
Many biologists would concur that ecosystems, not just species, need to be protected. However, accomplishing that goal by redefining species would make the laws that safeguard them—including the majority of our most important conservation laws—unsound. Zachos states, “All these quantifications of biodiversity also are arbitrary if what a species is ultimately arbitrary.” “And that is a bit of a frightening prospect. ”.
Cracraft made the decision to use this method for all birds worldwide a few years ago. He began working on a revised estimate of the number of bird species in the world with a small group of collaborators. A “species” was defined as any group that displayed a distinct, shared set of traits, regardless of whether or not it could mate with other “species” (henceforth referred to as “taxa”).
Cracraft claims, “We’re losing the battle because we’re fighting over a single endangered species.” Protecting charismatic species—such as stunning birds or mammals—tends to place more emphasis on them than on uncommon ecosystems or species collections. He contends that a legislative framework that would identify and safeguard groups of his rare taxa rather than individual species would be a potent force for conservation.
Some biologists even charge that those who define biodiversity using these kinds of “taxa” (also known as “phylogenetic species”) are deliberately attempting to subvert laws pertaining to conservation. Phylogeneticists, however, tell us that their position is not anti-conservation but rather that legislation protecting rare species fails to take the wider picture into consideration.
What’s the world’s bird population? Scientists turn to A.I.
Through a combination of citizen science and big data analytics, a 2021 study estimated the entire global population of birds is comprised of at least 50 billion wild birds.
Researchers in Australia combined nearly a billion bird sightings from eBird, an online database of bird observations maintained by the Cornell Lab of Ornithology and curated by citizen scientists, to estimate the total number of birds in the world. Over 600,000 people contributed information to the database. This information included the kind of bird seen, where it was seen, its size and color, whether it was near a city, and other elements that went into determining a species’ “detectability,” or the likelihood that an observer would see a specific bird.
Approximately 10,000 distinct bird species are known to exist, and 2092% of these species are covered in the eBird data base. The remaining 8 percent of species are extremely rare species that are seldom seen, which means that their numbers are extremely low and their exclusion from the analysis shouldn’t have a significant effect on the overall estimate.
Certain species are extremely abundant, while hundreds of species face extinction. Actually, four bird species—whose combined estimated population is over a billion—belong to what scientists refer to as “the billionaire club.” These include the house sparrow (1. 6 billion), followed by the European starling (1. 3 billion), ring-billed gull (1. 2 billion), and barn swallow (1. 1 billion).
However, while a small percentage of “one percenters” control the ecosystems, the majority are having difficulty surviving. Roughly 5% of the bird species included in the study had an estimated population of fewer than 5,000 as of 2012, making them extremely vulnerable to extinction. These include birds like the Invisible Rail, Noisy Scrub-bird, and Chinese Crested Tern.
In ten years, the researchers want to conduct a follow-up study to see how the most vulnerable species are doing. The state of these populations’ native ecosystems could be seriously threatened if they do poorly.
Naturally, because it is based on extrapolating sightings, this assessment cannot be considered definitive. When working with extremely large, worldwide datasets like eBird, some degree of uncertainty is to be expected, even though some of these sightings may not be accurate.
The scientists extend an invitation to all ardent birdwatchers to participate in eBird The researchers intend to carry out more thorough analyses as more data become available, which could result in a more accurate depiction of the condition of bird ecosystems worldwide. In the end, this knowledge will significantly influence conservation efforts to focus resources where they are most required.
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