List of birds by population
This is a set of lists of bird species by global population, divided by avian order. While numbers are estimates, they have been made by the experts in their fields. For more information on how these estimates were ascertained, see Wikipedia's articles on population biology and population ecology. Contributing organizations include the IUCN, BirdLife International, and Partners in Flight.
The global population of all mature birds is estimated to be 50 – 100 billion individuals. Total species population, including immature individuals, is higher during the breeding season of each species.
These lists are incomplete, because experts have not estimated all bird populations. For example, the spectacled flowerpecker was only discovered in 2010, and did not receive its scientific name until 2019, adding to the other 73 new bird species described by ornithologists from 2000 – 2009. Global population estimates for many of these at this time would lack accuracy.
All numbers are estimates, because they are made via bird surveys and extrapolating species density estimates made via observation data over a species' known range. Population estimates should be interpreted with a margin of error, even when only one value is provided.
The number of species within a order corresponds to IOC guidance unless otherwise noted. IUCN/Birdlife International taxonomic classifications often differ from the IOC; for specific disagreements, see Order specific pages.