Guwahati: One percent of the world’s birds have evaded documentation during the last decade, according to a new analysis. The Search for Lost Birds, a collaboration between Re, the American Bird Conservancy, and BirdLife International, has developed the most complete tally of bird species lost to science. Of the approximately 11,849 bird species, 126 meet the criteria of being “lost.”
These birds have not had a documented sighting in at least 10 years (meaning there are no photos, videos, or audio recordings of them), and they are not assessed as extinct or extinct in the wild by the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species.
The list of 126 lost birds includes two from India: the Himalayan quail and Jerdon’s courser. Jerdon’s courser was last documented in 2004. This nocturnal shorebird occurs in southern India and was believed to be extinct for most of the twentieth century until it was rediscovered by a local trapper in 1986. Since then, all confirmed records have come from the vicinity of a single wildlife sanctuary, where it occupies sparse foothill scrub.
The Himalayan quail was last documented in 1876. This distinctive quail is known from only two small areas of the western Himalayas. All documented records come from specimens collected between 1836 and 1876 in northern India. This enigmatic species seems to prefer the cover of tall grasses on steep slopes, which likely makes it very difficult to detect.
The Pink-headed Duck, listed as native to several countries in Southeast Asia, including India, Myanmar, and Bangladesh, is another iconic lost bird. Known for its pink plumage and elegant shape, this striking duck is thought to be primarily nocturnal and prefers secluded, densely vegetated wetlands. The last known captive individual survived until the late 1940s, while the last wild specimens were collected during the early 1920s.
“Birds are the most well-documented group of animals on Earth, and it’s a testament to just how much people love them that only about one percent of the world’s birds have evaded documentation during the last decade,” said Cameron Rutt, lead author of the paper and former lost birds science coordinator with the American Bird Conservancy. “Within that one percent, however, there are many highly threatened species that haven’t been recorded in decades. Finding these birds is essential to prevent them from slipping into extinction.”
Ornithologists with the Search for Lost Birds analyzed more than 42 million photos, videos, and audio recordings of birds collected by three citizen science platforms (The Cornell Lab of Ornithology’s Macaulay Library, iNaturalist, and xeno-canto), as well as museum collections and media from search engines and scientific research papers. They also conferred with local experts to identify birds that have not had a documented sighting between 2012 and the end of 2021.
The analysis, titled “Global gaps in citizen science data reveal the world’s ‘lost’ birds,” was published in the journal Frontiers in Ecology and the Environment on June 17. It initially identified 144 birds. In the two years since that initial analysis, the Search for Lost Birds has continued to track birds that have been rediscovered and taxonomic clarifications that no longer treat certain birds as separate species.
Fourteen of the original 144 species were recorded on citizen science platforms or documented by conservationists between 2022 and 2023. Two species were subject to taxonomic clarification.
Two species from the original list have populations in human care, so even though they have no recent documentation in the wild, they do not qualify as “lost.” These findings bring the current total of lost birds to 126.
The list includes species that have been lost for just over the 10-year threshold and others that have been lost for more than 150 years, such as the Jamaican pauraque, coppery thorntail, and New Caledonian lorikeet.
The most recently lost species, the Papuan whip-bird, hasn’t been documented by scientists or registered on citizen science platforms in 13 years. The white-tailed tityra is the longest-lost bird, with no confirmed sighting in 195 years. The Search for Lost Birds has made the list of all lost bird species accessible on its website, where bird scientists and enthusiasts can see the complete list and illustrations of every lost bird, as well as search for birds by species, location, or taxonomy.
“Figuring out why these birds have become lost and then trying to find them can feel like a detective story,” said John C. Mittermeier, director of the Search for Lost Birds at the American Bird Conservancy.
“While some of the species on the list will be incredibly challenging or maybe even impossible to find, others might reveal themselves relatively quickly if people get to the right places. Regardless of the situation, working closely with local people and citizen scientists is the best way to find lost birds and begin conservation efforts to ensure that these species don’t become lost again.”
Several of the lost species, including Itombwe nightjar, Jerdon’s courser, Himalayan quail, South Island Kōkako, Vilcabamba brushfinch, Negros fruit-dove, Siau scops-owl, and Cuban kite, are among the most wanted species that the Search for Lost Birds is hoping to rediscover with local partners.
However, the Search for Lost Birds invites sharp-eyed birders around the world to help find other species. If birders see one of the lost species and capture photos, video, or a sound recording of the bird, they can contact the Search for Lost Birds to help share their discovery and update the list.
Many of the lost bird species identified by the Search for Lost Birds live in the tropics, particularly on small islands or in mountainous areas. Oceania has 56 lost bird species, the most of any geographic area in the world, followed by Africa with 31, Asia with 27, South America with 19, North America with 13, and Europe with only one (note: some birds range across multiple regions).
The reasons why 126 species of birds are lost to science vary. Some of these birds are in areas that are difficult to reach, which has prevented conservationists from mounting searches to find them.
It is possible that although scientists have not seen these species, they are not lost to local and Indigenous communities, as was the case with the black-naped pheasant-pigeon in Papua New Guinea (its local name is Auwo).
Sixty-two percent of lost birds are threatened with extinction. Birds that are lost and inhabit areas where local communities, birders, conservationists, and ornithologists often visit are more likely to be endangered or critically endangered.
“Documenting the survival of lost birds is critically important for supporting next-step actions to conserve these species,” said Daniel Lebbin, vice president of threatened species at the American Bird Conservancy. “We need to confirm these birds survive and where to conserve their habitat.”
As climate change and biodiversity loss continue to impact the planet, ornithologists worry that some species may be at a higher risk of extinction than conservationists realize, even if they live in remote areas with enough habitat. Expeditions to find species could help mitigate threats to those species before they become worse.
“While birds are the most well-documented group, every additional data point helps focus the direction of the program,” said Christina Biggs, leader of the Search for Lost Species at Re
and co-author of the paper. “We want to make sure that our resources go toward preventing the extinction of the most threatened species, so this research is extremely valuable for us. As the sixth mass extinction progresses, we grow our scientific circles to include Indigenous, local community, and citizen science knowledge, every possible bit of information directed at halting biodiversity loss.”
Since its launch in 2021, the Search for Lost Birds and its partners have supported projects on lost bird species around the world, including the Santa Marta sabrewing in the Sierra Nevada de Santa Marta in Colombia, the Sinú parakeet in the Alto Sinú in Colombia, the black-naped pheasant-pigeon in Papua New Guinea, the Siau scops-owl and black-browed babbler in Indonesia, Urich’s tyrannulet in Venezuela, the pink-headed duck in Myanmar, the South Island kōkako in New Zealand, and the dusky tetraka in Madagascar.
The initial analysis to identify the birds lost to science was supported by the Constable Foundation. The Search for Lost Birds is supported by Allbirds.
Roger Safford of BirdLife International’s Preventing Extinctions Programme said, “Lost species, as well as being important conservation targets in their own right, are also unique representatives of the diversity of life in the place and habitat where they are found. We hope they are not gone forever and should do all in our power to prove this by finding them again and using what we learn to conserve them and the many other species sharing the extraordinary places where they live.”
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