Notes from the Field: Saving Tree Frogs in Honduras – Part I

The Detroit Zoological Society is collaborating with the Honduras Amphibian Rescue and Conservation Center to preserve three species of endangered frogs from the cloud forests of the Cusuco National Park in Honduras. The rescue center is an in-country facility that aims to re-populate these three endangered species through programs such as head starting, captive breeding, habitat protection and community outreach.

Amphibians all over the world are suffering extinctions, and the species in the Cusuco National Park are at a particularly high risk. There is a fungal disease, called chytrid, that is causing drastic population declines amphibians globally. Chytrid fungus has been particularly devastating to amphibians that live at higher elevations in the tropics, because the fungus thrives in lower temperatures and high humidity. This fungus likes to live in keratinized skin cells, and because amphibians rely on their skin to breath and exchange nutrients, it can be very deadly. The Cusuco National Park is a protected area that is home to many rare amphibian species who, unfortunately, are subjected to this fungal disease. The Detroit Zoological Society is working with the rescue center to investigate how to help save these animals from extinction.

While there are many species of amphibians in Honduras that need help, we decided to start our mission with three “target species” of critically endangered tree frogs. Once we find the best way to help these species, we can apply what we learned to others locally. These three target species are the exquisite spike thumbed frog (Plectrohyla exquisita), the Cusuco spike thumbed frog (Plectrohyla dasypus), and the mossy red eyed frog (Duellmanohyla soralia). All three of these frogs have been found to have the highest infection rates with chytrid fungus in the Cusuco National Park and are at high risk of extinction. This spring, we conducted fieldwork in Honduras, visiting the natural habitat of the three target species to help gain a better understanding of their behavior. We were able to observe some never-before-seen behaviors of these interesting animals that will help us increase our chances of protecting them.

Before I get too carried away, let me introduce you to the three species!

Photo by Jon Kolby

Exquisite spike thumb frogs are the largest tree frog in the Cusuco National Park at approximately 4 inches long. These frogs are found exclusively in the small protected area of the park, and are listed as Critically Endangered by IUCN. The frogs get their name from the large boney projection that males have on the sides of their thumbs, called a prepollex. It is theorized this special appendage is used for male combat, but combat has not yet been observed in this species. Additionally, the call of these frogs has never been heard (or at least recognized) by human ears.

Photo by Jon Kolby

Cusuco spike thumb frogs also only live in the small protected region of the Cusuco National Park; they are also listed as Critically Endangered. This species also gets its name from a prepollex in the males. Cusuco spike thumb frogs are medium-sized, growing to about 2 inches. Their call is a “quack” noise, similar to a duck. When threatened, these frogs have been observed jumping into leaf litter and burying themselves, which is unusual behavior for tree frogs.

Photo by Jon Kolby

Mossy red-eyed tree frogs are the smallest of the three target species, at a maximum of about 1.5 inches, and are also listed as Critically Endangered. As tadpoles, they have a striking green sheen to them, and they perform an odd behavior. They will flip over on their backs to swim – bellies up – in the rapids of waterfalls. Mossy red-eyed tree frogs can be heard calling with a series of chirps and clicks.

The Detroit Zoological Society and the Honduras Amphibian Rescue and Conservation Center have a plan to save these amazing animals. I’ll be sharing more details about this plan in upcoming blog entries, so stay tuned!

– Dr. Ruth Marcec is the director of amphibians for the Detroit Zoological Society and oversees the National Amphibian Conservation Center at the Detroit Zoo.

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