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Wednesday, April 30, 2014

Eager froglets hatched ready for leaping!

Posted by: Kirsten Pisto, Communications


Baby Solomon Island leaf frogs. Photo by Alyssa Borek/Woodland Park Zoo.

Solomon Island leaf frogs, Ceratobatrachus guentheri, also known as triangle frogs, are a very special type of amphibian because they go through their tadpole stage inside the egg, hatching as completely formed froglets. The juvenile frogs emerge from their eggs as fully developed frogs in a process called direct development. Instead of spending their first days as a tadpole, or polliwog, these frogs are hatched ready to leap! The tiny frogs grow very quickly, starting at only an eighth of an inch when they emerge. They eat very small insects until they are large enough to transition to an adult diet of arthropods and larger insects, and even smaller reptiles and amphibians.

The little froglets practice ambushing tiny insects, a behavior they will use later to pounce on any prey that happens to wander through their territory. It’s amazing to see these tiny creatures emerge from an egg and almost immediately become self-sufficient hunters. 

A pointy-nosed Solomon Island leaf frog on a mossy bed. Photo by Kirsten Pisto/Woodland Park Zoo.

In 1991, Woodland Park Zoo won a prestigious Edward H. Bean Award from the Association of Zoos and Aquariums for our Solomon Island leaf frog propagation program. The award recognizes a significant captive propagation effort that enhances conservation of the species. At the time, Woodland Park Zoo was one of the first facilities to breed a viable offspring of this species and was very successful with many births in 1989-1997. 

It wasn't until just recently that this species was brought back to the zoo in September of last year. The zoo now has 6 adults and 7 babies. The photo below, taken by Day Exhibit keeper Alyssa Borek, shows just how tiny these frogs appear! 

These babies were born at the zoo in early February. Photo by Alyssa Borek/Woodland Park Zoo.

The frogs are found on their native Solomon Islands and Papua New Guinea’s Buka Island and Bougainville Island, in a variety of habitats from dense rain forest to coconut plantations. They bury their eggs among the leaf-littered floor of the rain forest, often in the crook of tree roots or rotten stumps. The pea-sized eggs hatch in about one month, with the tiniest froglets appearing at a whopping 0.6 cm long.

These frogs are polymorphic, meaning there are many variations in color, from golden earthy browns to bright green. They also have special camouflage in the way they are shaped, with a triangle face that appears much like a leaf on the forest floor. 

The juvenile frogs are a light green right now, but their coloration may change as they mature. Photo by Kirsten Pisto/Woodland Park Zoo.

If you were walking through the rain forest at night, you would hear these frogs much sooner than you would see them. The frogs have a very unique call, a sharp barking noise that is often mistaken for a small dog. The barking begins when the sun goes down and the frogs begin to sing.

Adult Solomon Island leaf frogs chill out together in their leafy exhibit. Photo by Kirsten Pisto/Woodland Park Zoo.

The Solomon Island leaf frogs at the zoo can be found in the Day Exhibit, kept in a mossy, warm (78°F) and humid (80%) environment. Because the frogs are nocturnal their environment is kept dimly lit, which also mimics the shadowy rain forest floor. The exhibit has special hiding places for the frogs, so you have to look closely to spot them. They eat insects, mealworms and sometimes a special treat— earthworms. 

This frog blends in with its leaf nest, perhaps protecting a clutch of eggs. Photo by Kirsten Pisto/Woodland Park Zoo.

Next time you are in the Day Exhibit, be sure to check out these amazing amphibians!

2 comments:

  1. Off topic question here. Why is it still called the Day Exhibit when there's no Night Exhibit? Couldn't it just be the Reptile (and Tree Kangaroo) House?

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    1. Hey, anon!

      What an interesting question. The animals in the Day Exhibit represent reptiles, amphibians and mammals, with room for invertebrates too. We like to capture that sense of biodiversity in our exhibit themes and titles, which tend to be more inclusive.

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