The Other Marthas


Meet Toughie, the very last Rabbs’ Fringe-limbed Tree Frog.

marthas1.jpgThe Rabbs’ Fringe-limbed Tree Frog (Ecnomiohyla rabborum) was a nocturnal species, capable of parachuting several meters between trees in the forest canopy by jumping into open air and spreading its wide, webbed feet. The male assumed all of the parental care, feeding the tadpoles with his own skin cells and defending their pool of water from other frogs and would-be predators.

Only discovered in 2005 and not formally described until 2008, none have been reported in the wild since 2007. Toughie, along with others of his kind and about 20 other species, were hastily collected by a team of herpetologists from a mountain in Panama when the deadly chytrid fungus was detected there in 2006.

Although a clear link has not been established, the chytrid fungus Batrachochytrium dendrobatidis or Bd, is possibly carried and spread by the non-native and non-susceptible African Clawed Frog (Xenopus laevis, below). The African Clawed Frog is extremely adaptable and hardy, and a model species for a variety of biological and biochemical research applications; before test kits, they were used to confirm pregnancy. Also kept as pets as early as the 1950s, they were introduced to multiple continents, and are illegal to transport or own without a permit in several U.S. states.
 

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Bd thrives in cool, wet climates—such as cloud forests. An infection from this fungus (chytridiomycosis) affects the skin, but ultimately the frogs die of heart failure due to electrolyte loss. Populations of amphibians worldwide have been declining precipitously since the 1980s, although the cause was not known. A recent study reported that the fungus is present in Northeastern U.S. frog specimens dating from the early 1960s. Today, up to 30% of frogs in the Northeast carry the infection. But Bd was not identified as a threat to amphibian populations until the late 1990s—too late for many species.

The fungus may be at least partially responsible for the sudden extinction of the Golden Toad (Incilius periglenes, below) in the Monteverde cloud forest in Costa Rica. In 1987, 1500 males were spotted over a 3-month period. In 1988, only one male was seen. None have been reported since 1989, and the species was declared extinct in 1992. Captive individuals died of unknown causes in the mid-1980s.
 

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Also among those that fell to Bd’s axe is the Panamanian Golden Frog (Atelopus zeteki, below), which is actually a toad. It has not been seen in the wild since 2007; however, over 500 exist in a variety of captive breeding facilities worldwide, including the Columbus Zoo!
 

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Panamanian Golden Frog, Atelopus zeteki

This species is unique in that it waves to potential mates and rivals, thought to be an adaptation for communicating in stream habitats where the sound of its call might be drowned out. The incomparable Sir David Attenborough shows us how:

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Although there is still hope for this species, the likelihood of reintroduction back into the wild is low, as the fungus is still present and much of the toad’s cloud forest habitat has been destroyed.

If that wasn’t enough, a recent article reports that populations of amphibians in Spain are being decimated by a virus that has been present in Spain for some time, but which is now mysteriously causing massive die-offs in relatively pristine areas.

Stories like these are enough to cause some trepidation in even the staunchest endangered species advocate; and funding is plummeting for wildlife studies that help save species. Although the loss of biodiversity is becoming commonplace, we CAN bring species back from the brink—given the proper tools, time frame, and legislation, anything is possible. And of course, an indomitable will never hurts.

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The Mauritius Kestrel (Falco punctatus) is one such success story. Native to the same island off the eastern shore of Madagascar that the Dodo once famously inhabited, the kestrel’s population also began to decline after the arrival of Dutch explorers. Widespread deforestation by the Dutch and later the French and English over four centuries, combined with the introduction of nonnative mammals (mongooses, rats, cats, and monkeys), caused its decline both directly and indirectly. By the turn of the 20th century only a few hundred remained in the most remote parts of the island.

Finally, in the 1950s a malaria epidemic ravaged the human population, leading to the widespread spraying of DDT to reduce mosquito numbers. DDT causes eggshell thinning in all birds, but top predators like the kestrel are hit the hardest due to bioamplification. By 1974, four birds remained in the wild. Only one was a breeding female.

Thanks to the tireless and nearly singlehanded efforts of Welsh biologist Carl Jones, using methods that flew in the face of the accepted conservation techniques of the time, the Mauritius Kestrel no longer hovers on the brink of extinction. Jones climbed trees and cliff sides to collect eggs from wild nests, incubated them in captivity, cross-fostered the chicks with analog species, soft-released the young kestrels, and supplemented food to the wild adult birds so they were able to lay more eggs—initially, largely on his own dime, as there was little funding to support the kestrel’s recovery. After 20 years, there were over 200 birds in the wild. Today there are three distinct populations on the island, with the total being around 400 adult birds. Jones has also assisted with the recovery of several other imperiled Mauritius species, and even began to bring an entire forest ecosystem back byre-introducing an ecological analog of the island’s extinct giant tortoise from the Seychelles.

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The Aldabra Tortoise, Aldabrachelys gigantea

Giant tortoises are a common phenomenon on remote islands; only slightly less common is the tendency for humans to drive them to near or total extinction. Early explorers used them as food, as they could be stowed alive on their backs in the ship’s hold without food or water for up to a year.  In addition to Mauritius, the nearby island of Reunion had its own giant tortoise, as did Rodriguez, Madagascar, New Caledonia, several of the Seychelles Islands, and of course, the Galapagos islands. They all became extinct or critically endangered shortly after being visited by humans.

The call of the Rabbs’ Fringe-limbed Tree Frog has not been heard in the wild since 2007, and the last remaining male stopped calling shortly after it was taken into captivity in 2005. The species was bred successfully but the tadpoles failed to develop properly, and soon the population was down to 2 adult males. Early in 2012, one of the males began to decline sharply in health. Rather than risk him passing away overnight the researchers decided he should be euthanized to preserve his precious genetic material (frogs decompose quickly). Their call has never been recorded, and will never be known to science.

That is, not until just a few days ago!!

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What prompted this lone male to suddenly call after nearly 10 years of silence is unknown. We have no way of knowing if this is a typical vocalization for the species. But it’s the only recording we have.

So what’s the point? Who cares if he’s the very last? How is the loss of one more species among millions going to make any difference?

In the words of Richard Conniff,

“Wildlife is and should be useless in the same way art, music, poetry and even sports are useless. They are useless in the sense that they do nothing more than raise our spirits, make us laugh or cry, frighten, disturb and delight us. They connect us not just to what’s weird, different, other, but to a world where we humans do not matter nearly as much as we like to think.”

His opinion piece in its entirety can be found here.

Martha, the very last passenger pigeon, died in a zoo in 1914. After 100 years of technological and scientific breakthroughs, one might hope that we’d have both the wisdom and ability to prevent any more reincarnations of Martha. This holiday season, consider donating to the wildlife conservation fund of your choice, and help save others from Toughie’s fate.

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Posted December 18, 2014

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