How Many Birds Are in the World? Species, Numbers, and Facts

Birds are everywhere: from the poles to the open ocean to the jungles to our backyards. Birds are widespread and abundant, but has anyone ever tried to count them all? We can’t go out and tally every single individual bird in the world, but scientists have estimated that there are something like 85 billion birds on Earth. That means there are about 10 birds for every one human. 

Scientists estimate that there are something like 85 billion birds in the world, but let’s break that number down. Of those 85 billion, 35 billion are estimated to be domesticated birds. Some studies count only wild birds, but domestic birds are birds, too!

The vast majority of domestic birds on this planet – some 33 billion, according to the Food and Agriculture Organization (FAO) of the United Nations – are chickens. Chickens are an incredibly valuable livestock species, providing eggs, meat, and feathers to humans all over the world. Today’s poultry chickens are the descendants of wild Red Junglefowl domesticated in Asia as many as 9,500 years ago. The FAO estimates that there are nearly 2 billion domestic birds of other species, including ducks, turkeys, guineafowl, and geese.

The rest of the birds on Earth, some 50 billion individuals, are wild birds. That number was most recently estimated as part of a paper published in 2021 in the Proceedings of the National Academy of Sciences, which used data from the worldwide bird sighting database eBird and compared them to other official sources. That 50 billion includes every wild bird on the planet: every penguin, parrot, heron, woodpecker, ibis, albatross, and every other bird in the world.

Though scientists estimate that there are 50 billion wild birds on earth, that number is decreasing. Many factors impact the number of birds in the world. 

One of the most widespread factors affecting bird populations is habitat loss. Many birds need specific habitats in order to live. Tree Swallows need open fields to find their insect prey, for example, while Pileated Woodpeckers need large trees for nesting and feeding. If those habitats change, those birds can’t get the food they need, and can’t survive. Humans are altering habitats all over the world, cutting forests for development or agriculture, draining wetlands, and otherwise changing the landscape. Habitat loss is a worldwide problem, so widespread that it’s difficult to measure. The U.S. Fish and Wildlife Service, for example, recognizes that humans destroy or degrade millions of acres of bird habitat each year in the U.S.A, but isn’t able to estimate the actual number of birds killed by habitat loss.

Human development is altering bird habitat in another way: causing long-term shifts to temperatures and weather patterns on Earth. The primary driver of climate change is humans burning fossil fuels, like oil, coal, and gas, for energy. Burning these fuels puts carbon dioxide into the air, ultimately trapping heat in our atmosphere causing global temperatures to warm. Climate change threatens habitats around the world by causing areas to become drier or wetter; causing waters to warm and sea levels to rise; and driving increases in extreme weather.

Some birds are impacted when they suddenly have to compete with creatures they’ve never encountered before. Humans have either accidentally or purposefully brought plants and animals that evolved to live in one place into a completely new place. Sometimes these species find themselves able to outcompete species in their new homes, and spread widely without opposition. For example, humans introduced Brown Tree Snakes to the island of Guam in the 1940s. The snakes had no predators on Guam, and the island’s native birds had no defenses against snakes. The introduced snake exploded in numbers and eventually helped cause the extinction of many of the island’s forest birds. Similar examples of invasive species problems are occurring around the world. 

Many human activities leave pollution or other waste on the landscape that can harm birds. Many seabirds accidentally ingest floating plastic pollution, which then may become trapped in their stomachs. Some scientists estimate that 99% of all seabirds could be tainted by plastic by 2050. Oil spills, like the 1989 Exxon-Valdez tanker or the 2010 Deepwater Horizon spill, can kill birds and other marine wildlife. Air pollution can result in high levels of toxins like lead or mercury that may impact birds.

The direct take of birds for food can have drastic impacts on bird numbers. The Passenger Pigeon was once among the most abundant birds on Earth, but rampant and unregulated hunting, coupled with habitat loss, caused the species to go extinct from its North American range in the early 20th century. Hunting is better regulated in many areas today, but it remains a major contributor to bird declines in some areas, especially tropical regions.