The natural world holds mysteries, including the astonishing reappearance of species once believed lost. These “Lazarus species” challenge our understanding of extinction, offering hope and highlighting life’s resilience.
Clarifying Extinction and Rediscovery
A species is officially “extinct” when no reasonable doubt exists that the last individual has died. This differs from “extinct in the wild,” where a species survives only in captivity or outside its natural habitat. “Lazarus species” are organisms thought extinct but later rediscovered alive, often after many years. This name comes from the biblical figure Lazarus, said to have been raised from the dead.
The International Union for Conservation of Nature (IUCN) maintains a Red List, assessing species’ conservation status. This assessment helps determine if a species is considered extinct or critically endangered. Despite rigorous assessments, proving extinction is difficult, especially for elusive creatures in remote areas, meaning some species might persist undetected. Rediscovery does not mean a species was never endangered; rather, it indicates a hidden population survived, often in perilously low numbers.
Animals That Reappeared
Several animals have made reappearances after being presumed extinct, captivating scientists and the public.
One celebrated example is the Coelacanth, a lobe-finned fish thought to have vanished around 65 million years ago. In 1938, a live specimen was caught off South Africa by Marjorie Courtenay-Latimer. This was significant, as the Coelacanth had only been known through fossil records. A second species was later found near Indonesia in 1997 and 1998. These deep-water dwellers likely evaded detection due to their habitat.
Another remarkable rediscovery involves the Takahē, a large, flightless bird indigenous to New Zealand. It was believed extinct after 1898, its population decimated by introduced predators and habitat loss. In November 1948, a small population was rediscovered in a remote valley of the Murchison Mountains in New Zealand’s South Island. This initiated New Zealand’s longest-running endangered species program to protect the approximately 500 remaining birds.
The Lord Howe Island Stick Insect provides another compelling case. This large, flightless insect was abundant on Australia’s Lord Howe Island but presumed extinct by the 1920s due to introduced black rats. For over 80 years, it was believed gone until a tiny remnant population was found in 2001 on Ball’s Pyramid, a volcanic sea stack off Lord Howe Island. This discovery highlighted how small, isolated habitats can serve as refuges for species.
The Bermuda Petrel, or Cahow, offers an example of recovery. This pelagic seabird was thought extinct for 330 years, largely due to hunting and introduced predators. In 1951, a small population was rediscovered on remote islets in Castle Harbor, Bermuda. Its eerie night calls, which led early European explorers to call Bermuda an “island of demons,” gave it its local name, Cahow.
How Rediscoveries Occur
The rediscovery of species often results from persistent scientific investigation and exploration of inaccessible environments. Improved survey techniques, such as specialized cameras and DNA analysis, enable researchers to detect elusive animals. Scientists may also re-evaluate historical records or local knowledge, as some species are known to local communities long before official scientific rediscovery.
Many rediscovered species survive in remote, isolated habitats that offer refuge from threats. These areas, such as deep ocean trenches, dense cloud forests, or isolated islands, can protect small populations from human disturbance and introduced predators. In other cases, species may be naturally rare or have behaviors that make them difficult to observe, such as being nocturnal or highly camouflaged.
Protecting Rediscovered Species
Once a “lost” species is found, immediate conservation efforts are important for its long-term survival. These efforts often involve strict habitat protection for the remaining population. Intensive population monitoring is also important to track the species’ numbers, health, and ecological needs. For critically endangered species, captive breeding programs may be established to increase their numbers in a controlled environment.
Reintroduction programs, such as for the Takahē and Lord Howe Island Stick Insect, aim to establish new populations in protected areas free from threats. These initiatives often require comprehensive predator control and habitat restoration for the species to thrive. Despite these efforts, ensuring the long-term viability of rediscovered species remains a significant challenge, as many face ongoing threats from habitat loss, climate change, and invasive species.