New Analysis: 126 Birds Lost to Science – no Confirmed Sighting in at Least a Decade

As part of the project The Search for Lost Birds, a collaboration between Re:wild, the American Bird Conservancy, and BirdLife International, the most comprehensive listing of bird species considered lost to science has been created. A newly published study in the journal Frontiers in Ecology and the Environment reveals that out of approximately 11,849 known bird species, 126 are classified as “lost.” These species have not been documented for at least ten years, meaning there are no current photos, videos, or audio recordings of them. Additionally, they are not listed as extinct or extinct in the wild on the IUCN Red List.

As Cameron L. Rutt, the lead author of the study, emphasizes, birds are the most well-documented group of animals on Earth. Nonetheless, there are species that have not been seen for decades or even centuries. For example, the nocturnal Jamaican poorwill (Siphonorhis americana) was last documented in 1860. However, a sighting of unidentified nightjars in 1980 prompted the IUCN to classify the species only as “critically endangered (possibly extinct).” The last confirmed observation of the Himalayan Quail was even longer ago, 147 years.

The South Island kokako of New Zealand’s South Island has also been considered long lost. The last confirmed sighting of this bird dates back 114 years. However, recurring, albeit unconfirmed, sightings provide hope that this species may have survived and could possibly soon be removed from the list of lost bird species.

Other species have not been lost for as long. For example, the Mayr’s forest rail (Rallicula mayri), endemic to New Guinea, was last documented in 2005. The turquoise-throated puffleg, native to Ecuador, has been considered lost since 1960. Similarly, the iconic ivory-billed woodpecker and the imperial woodpecker from North America, both last documented in 1967, are on the list of lost bird species.

How can bird species become lost?

There are many reasons why these 126 bird species cannot be found. Some of the birds live in areas that are difficult to access, making it hard for conservationists to conduct targeted search operations. There is also the possibility that these birds are considered lost only to science, while local and indigenous communities may still observe them.

A notable example is the black-naped pheasant pigeon, which was considered lost for 140 years and was finally rediscovered in November 2022 during a targeted search in the interior of Moratau, a volcanic island belonging to Papua New Guinea. Before this rediscovery, the species was only known from two specimens collected in 1882.

Why is the documentation of lost bird species important?

A staggering 62 percent of bird species considered lost are endangered. Therefore, documenting such a species is crucial for developing effective conservation measures to ensure their survival. Rediscovering lost bird species is likely the only way to prevent their ultimate extinction.

“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,” explains John C. Mittermeier, Director of the American Bird Conservancy. “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.”

Three citizen science platforms – Cornell Lab of Ornithology’s Macaulay Library, iNaturalist, and xeno-canto – as well as museum archives and media from search engines have proven to be valuable tools in the search for lost bird species. Ornithologists have analyzed over 42 million photos, videos, and audio recordings in this effort to find clues about the presence of these rare species.

The Search for Lost Birds project has already recorded several successes in the past, including the rediscovery of the Santa Marta sabrewing (Campylopterus phainopeplus) in Colombia in August 2022, which had not been documented since 2010. Furthermore, researchers succeeded in rediscovering the dusky tetraka (Xanthomixis tenebrosa), considered lost since 1999, at two different locations in Madagascar in December 2022 and January 2023.

Original List Recorded 144 Lost Bird Species

While the initial analysis two years ago listed 144 bird species considered lost, the current study titled Global gaps in citizen-science data reveal the world’s ‘lost’ birds now includes only 126 species. This decrease can be explained by the fact that two species are no longer regarded as separate species taxonomically. Additionally, 14 of the original 144 species were recorded on citizen science platforms or documented by conservationists between 2022 and 2023. For two more species from the original list, it was discovered that populations exist in human care, thus they are no longer considered lost.

The Search for Lost Birds project’s website allows anyone interested to view the complete list of lost bird species. Here, bird scientists and enthusiasts can find illustrations, information on taxonomy, distribution areas, the timing of the last documentation, and the current IUCN status for each species.

The project invites bird watchers worldwide to participate in the search for these lost species. Should anyone spot one of the lost species and capture photos, videos, or audio recordings, they can share these through the project, helping to update the list of lost species.