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Good Dads Help Rare Haitian Frogs Breed in Captivity

The views expressed are those of the author and are not necessarily those of Scientific American.


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La Hotte land frogIt requires a great deal of patience and more than a few days to get to the few remaining habitats of the La Hotte land frog (Eleutherodactylus bakeri) in Haiti. First you rent a pickup truck in Port-au-Prince. Then you drive 11 hours west down the Tiburon Peninsula. At one point the road passes through a river where you may need to wait up to three days until the waters are low enough to cross. After that you start driving up the steep, scarred roads of the Massif de la Hotte mountain range. Finally, you reach an area where you can drive no farther. You hire a local crew of porters and guides and hike for another four hours. Only then, at an elevation of about 1,800 meters, do you find yourself in a tiny fragment of a once-massive forest. “Everything on the journey up until that point is just barren land,” says Carlos Martinez Rivera, amphibian conservation biologist with the Philadelphia Zoo. “It’s just hills and hills of grassy fields and a few trees here and there.”

As much as 99 percent of Haiti has been deforested over the past few decades, as the country’s desperate people have cut down trees to make way for agriculture or charcoal production. This massive habitat loss has put the entire nation’s biodiversity at risk. Only a few untouched habitats remain.

The La Hotte land frog’s habitat is one of those areas. “It’s a very beautiful forest,” Martinez says. “There are a lot of tree ferns, pines and magnolia trees. It feels like going to any other tropical rainforest. But it’s a very tiny patch of forest.” The trees are still being cut down to produce charcoal or to clear land for cash crops such as parsley, celery, broccoli and carrots.

With so much of the country already deforested and more trees likely to be lost in the coming years, the Philadelphia Zoo in 2010 set out to save some of Haiti’s endemic frogs that live in those fading forests. They captured 154 frogs from nine species and brought them back to Philadelphia to establish a captive breeding program. “You can protect wildlife like frogs in a small space,” says the zoo’s chief operating officer, Andy Baker. “Trying to keep a genetically viable population of tigers takes the entire global zoo community, whereas in a relatively small room you can hold a genetically and demographically viable population of an entire species of frog. Our return on investment on species protection for animals like reptiles, amphibians and invertebrates can be very high.”

La Hotte land frogAnd indeed, the return has been high. The zoo now holds more than 1,500 Haitian frogs, all descended from those original 154. The star breeder among the group has been the La Hotte land frog, which now numbers about 1,200 of the total.

Biology and behavior have helped the seven-centimeter La Hotte frogs do well in captivity, Martinez says. The females can lay clutches of more than 100 eggs, which the males then guard until they hatch. “That frees up time and energy for the females to mate with other males and lay more eggs,” he says. “They’re very prolific in that sense.” The frogs don’t have a tadpole stage; instead they emerge from the eggs as tiny froglets. The fact that the frogs are not aquatic makes it easier to keep them alive and breeding because the zoo does not need to focus on the water’s pH as with in other amphibian captive-breeding programs. Rather, it can concentrate on simulating the temperature and rainfall of the original high-elevation habitats.

The success of the La Hotte frog contrasts with some of the other species, such as the miniscule Macaya breast-spot frog (E. thorectes), whose larger females only reach about 2.5 centimeters. “A female from this species at the most can lay two eggs,” Martinez says. “They’re so tiny that’s the most they can do.” The eggs are so small that “it’s easy for them to dry up if we don’t mist them enough or to drown if we mist them too much or go moldy if they’re too protected from the air. When those guys hatch they’re so tiny they can actually drown in a drop of water.”

Martinez explains that almost nothing about the ecology of the nine species was known prior to bringing them into the captive-breeding program. “All we know is the species’ names and the habitat where they live, but not where and when they nest. We assumed that the land frogs breed during the rainy season, and that appears to be the case.” The zoo exchanges what it learns with various agencies and organizations in Haiti while also working on strategies to either protect the remaining habitats or re-create them with newly planted trees. Earlier this year Haiti announced an initiative to plant 50 million trees by 2016.

The reforestation project, which experts say must come with ways to help the people of Haiti make a living, can’t come soon enough. “There are a number of species on Haiti that are in critical condition without any great confidence that their habitats are safe for the next decade,” Baker says. “We are truly looking at biodiversity loss on a national level.”

“That’s why we decided to take these frogs into the zoo,” Martinez says. “If you do have a doomsday scenario where the forest is gone, the species will still be preserved. We can re-create the forest in another area and maybe reintroduce the frog back into that habitat.”

Unlike a lot of other organizations which have gone to Haiti to collect data and never returned, the Philadelphia Zoo has made a long-term commitment to working with Haitian ministries, universities and other organizations to preserve both species and their habitats. Next month they will hold a workshop with government ministers and park rangers to share the information they have learned so far and get Haitian officials’ input on how to help conserve the area’s little remaining forest. Beyond that they will continue to concentrate on breeding the frogs in Philadelphia. “The real test of success,” Baker says, “is not just reproduction but survival to maturity and then your captive-bred animals reproducing themselves.” With three generations of La Hotte land frogs and a probably fourth in the near future, they’re already on that path.

Photos by and courtesy of Carlos C. Martínez Rivera, the Philadelphia Zoo

John R. Platt About the Author: Twice a week, John Platt shines a light on endangered species from all over the globe, exploring not just why they are dying out but also what's being done to rescue them from oblivion. Follow on Twitter @johnrplatt.

The views expressed are those of the author and are not necessarily those of Scientific American.





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