There are many birds in your area

Worldwide bird count: Sparrow is the most common bird in the world

Australian researchers have evaluated and extrapolated bird sightings all over the world: there are around 50 billion birds in the world - so there are six birds for every human being. Sounds like a lot of birdies. However, the scientists also found that they are distributed very unevenly: There are very few species of birds with more than a billion specimens. Most species have become rare or even very rare. One of the most famous birds is the house sparrow, also known as the sparrow and also in our home. But even its stocks are shrinking. According to the researchers, knowing how often a species occurs where is important in order to be able to take measures to protect it in good time.

Four bird species with more than a billion individuals - the front runner is the sparrow

According to calculations by the team led by William Cornwell from the University of New South Wales in Sydney, there are only four bird species, of which more than a billion individuals exist: the front runner is the house sparrow or sparrow (Passer domesticus) with 1.6 billion specimens of the world. There are also an estimated 1.3 billion starlings (Sturnus vulgaris), 1.2 billion ring-billed gulls (Larus delawarensis) and 1.1 billion barn swallows (Hirundo rustica).

There are fewer than 5,000 birds of every tenth species

The scientists also found that there are only fewer than 5,000 animals left of around twelve percent of the bird species - these include the extremely rare amber tern (Thalasseus bernsteini), the long-bellyed thicket bird (Atrichornis clamosus), which was believed to be extinct, and the flightless drum rail ( Habroptila wallacii). There are probably only about 100 specimens left of the runner Turnix melanogaster in the world.

The rarest bird families: kiwi fruit and stilt claws

The researchers also wanted to find out whether a rare occurrence is typical of certain groups of birds. They couldn't find a general pattern. The rarest were birds from the kiwi families, of which there are an estimated 3,000 animals left in the world, and the stilt-claws with 154,000 birds. The researchers write that quantifying the abundance of a species is a crucial first step in its conservation.

"By correctly counting what's out there, we learn which species might be vulnerable and we can see how those patterns change over time." Corey Callaghan, University of New South Wales

Worms are the most popular bird food

However, the scientists not only found out how many birds of how many species there are in the world, but also what they feed on: All over the world, birds prefer to eat invertebrates such as worms. According to the scientists, this applies to an estimated 15 billion birds. 13 billion birds are omnivores. Birds that feast on flower nectar are far rarer - that's around 479 million animals. The rarest of all, with 194 million specimens in the world, are birds that eat carrion.

Scientists also used data from citizen researchers

For their investigation, the team led by William Cornwell from the University of New South Wales in Sydney combined scientific surveys of individual species in certain distribution areas with entries from an Internet database called "eBird". Around 600,000 citizen scientists have already entered almost a billion bird sightings in it.

Using the research data, the scientists determined how many of them are estimated to occur per unit area for 724 species. They compared the value with the frequency of the sighting on "eBird". They also took into account how often a species of bird is likely to be spotted by humans based on its appearance and lifestyle: birds that breed near settlements are spotted more often than those that are found in remote areas.

Worldwide frequency of 92 percent of all bird species estimated

From this, the researchers developed an estimate for the global abundance of 9,700 bird species. That is about 92 percent of all known bird species. The scientists did not include the remaining eight percent due to the uncertain data situation. However, since all of these are rare species, their number would hardly add to the total number of birds, the researchers explain.

Count birds regularly to protect them

The researchers write that the development of the population could be recorded every five to ten years. "If their population falls, this could be a real alarm bell for the health of our ecosystem," says William Cornwell. The scientists assume that their method could also be used for other animal species. And they advocate that as many interested laypeople as possible work as citizen scientists, take part in campaigns and report their sightings.

"It can be as simple as checking to see if you can see something out the window while you have your morning coffee." William Cornwell, University of New South Wales