Gladitator frog (Hypsiboas rosenbergi)

Cute Frog of the Week: Oct. 10, 2011

This incredible image is the winner of our Golden Frog Day photo contest. Congratulations to Harold Henry, who took this great photo of the gladiator frog. Nice work!

Gladiator frogs are aptly named. Males are known for their aggressive behavior toward one another both during mating season and while guarding clutches of eggs. In fact, males even have a small, sharp spike on each hand that grows out of their wrist by the base of their thumbs. They use this as tiny daggers while fighting, and they have been seen tearing at each other with them, often causing significant damage or death. The eyes and face are the easiest, most common targets, and many individuals bear battle scars.

The male frogs are nest-builders, either digging out small clay or sand basins on the edges of streams or ponds, or utilizing natural ones, such as footprints, where the female will lay her eggs. Some researchers believe this is the cause of the aggression—they compete to this extent because of the small size of available breeding areas. Males will even return to nest sites and guard the eggs until tadpoles have hatched. Interestingly, biologists have noticed that this fighting behavior was only prevalent in populations in Panama, but was not seen in Costa Rica, where there were larger areas for nest-building and egg-laying available. These frogs are most commonly found in Costa Rica and Panama, where their populations are decreasing, according to the International Union for the Conservation of Nature.

Photo by Harold Henry.

Every week the Panama Amphibian Rescue and Conservation Project posts a new photo of a cute frog from anywhere in the world with an interesting, fun and unique story to tell. Be sure to check back every Monday for the latest addition.

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