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The “Romeo Problem”—When to Declare a Species Extinct

The pileated woodpecker.
“Nostalgia for the good old days when everything was abundant is almost universal among conservationists…We lament the lost thunder of galloping buffalo, the sky-darkening clouds of pigeons and waterfowl, the flowing sea of the prairies, the velvet silence of the virgin woods…There are two possible explanations. Appreciation may have been enhanced by the intervening gains in education, or we may be incapable of appreciating anything until it has grown scarce.”
— Aldo Leopold, “Scarcity Values in Conservation” (1946)

Shakespeare provided us with the cautionary tale of Romeo and Juliet. Romeo mistakenly thought the unconscious Juliet was dead and abandoned hope, with tragic consequences. By analogy, if a species is mistakenly declared extinct, conservationists may give up on it. If the species, in fact, still survives, that could have tragic consequences that hasten the species’ eventual demise, such as no longer protecting its critical habitat.

So, how do we decide if a species is really extinct? The International Union for the Conservation of Nature (IUCN) manages the global Red List and provides the most definitive criteria: “Extinct” means there is no reasonable doubt that the last individual has died. “Presumed Extinct” means exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual. By that standard there was never any risk in declaring the Passenger Pigeon to be extinct since we knew to the hour when the last individual, Martha, died in her cage at the Cincinnati Zoo in 1914. But for most other species the death of the last individual goes undocumented, so “presumed extinct” is the safer call.

Bachman's warbler
Image of a male Bachman’s warbler by Jerry A. Payne

Last September, after a 5-year review, the US Fish and Wildlife Service (USFWS) made a bureaucratic decision to declare 11 bird species currently listed as “endangered” in the US to be extinct and no longer requiring the legal status afforded by the Endangered Species Act. Here are the birds now presumed to be lost:

  • Ivory-billed Woodpecker: Last seen in 1944
  • Bachman’s Warbler: Last seen in 1988
  • Bridled White-eye: Last seen in 1983
  • Kaua’i ‘akialoa: Last seen in 1969
  • Kaua’i nukupu’u: Last seen in 1899
  • Kaua’i ‘ō’ō: Last seen in 1987
  • Large Kauai Thrush: Last seen in 1987
  • Maui ākepa: Last seen in 1988
  • Maui nukupu’u: Last seen in 1996
  • Molokai Creeper: Last seen in 1963
  • Po’ouli: Last seen in 2004
Image of Poʻouli by Paul E. Baker
  • Declaring these species to be extinct has both legal and biological implications. Once a species is extinct it may no longer be afforded special protections under national and international conservation measures. For the 11 birds recently declared extinct, many provisions of the Endangered Species Act will no longer apply. That means, for example, that there would no longer be a strong motivation to preserve critical habitat for those species.
But just as Juliet’s demise was premature, some birds that have been widely regarded as extinct are rediscovered, often long after their presumed demise.
  • But just as Juliet’s demise was premature, some birds that have been widely regarded as extinct are rediscovered, often long after their presumed demise. That has happened often enough that we have a term for the phenomenon, a “Lazarus species,” a species that returns from the dead. For example, the New Zealand Storm Petrel was presumed extinct, having not been seen since 1850. Then in 2003, it was photographed, and in 2005 three birds were captured at sea, fitted with radio-transmitters, and tracked back to their breeding location which was then protected in 2013. The storm petrel spends most of its life at sea, and when it does return to land it is largely nocturnal, so it was easy for the bird to go undetected for 150 years. That’s the case with most Lazarus species; for a variety of reasons, they’re hard to detect and hence can be easily overlooked if few remain.
Ivory-billed Woodpecker
Image of an Ivory-billed Woodpecker by Jerry A. Payne
  • In April a research team made the newsworthy announcement that after three years of searching they had photographic evidence the Ivory-billed Woodpecker, so recently declared extinct, still existed in the swamp forests of Louisiana. If that claim withstands peer review by the scientific community, it would be another example of a Lazarus species reemerging from presumed extinction. There has been no shortage of reports of the elusive bird since 1944, but none have withstood careful scrutiny, and some were outright hoaxes. The decision by the USFWS to declare the Ivory-billed Woodpecker officially extinct was based in part on the fallout from a previous alleged rediscovery in Arkansas in 2004. The initial photographic evidence in that case was later debunked, but it triggered a massive, multi-year effort to find the birds. On the chance the birds still existed, a lot of swamp forest habitat in Arkansas was quickly protected, so something good did result even though no birds were found. Ironically, the multi-year, yet-futile search provided much of the justification for the 2021 USFWS declaration.
  • Some ornithologists think there are reasons to remain guardedly hopeful that the Ivory-billed Woodpecker still exists somewhere in the US: They are hard to find in difficult to survey habitat and may be wary of people; their swamp forest habitat has been recovering since the last confirmed sighting; until now no major systematic searches have taken place in potential habitat outside of Arkansas; and the IUCN still regards the species as only “critically endangered.” Other ornithologists think there are reasons to be skeptical. Lots of people have searched in vain for the bird over the years; there still aren’t enough large, contiguous areas of older swamp forest to support a viable population; and it has now been almost 75 years since it was last confirmed to exist in the US.
  • Whether the Ivory-billed Woodpecker belongs on the list of Lazarus species or the list of extinct species remains to be seen, but just as the 2004 alleged sightings triggered renewed efforts to locate any surviving birds, the recent alleged sightings will surely inspire some to continue the quest.

To learn more about the author, Stanley Temple, click here.Curious about the Leopold-Pine Island Important Bird Area? Learn more here.