Harlequin Frogs True Toads and Relatives: Bufonidae

Physical characteristics: Also known as the harlequin toad, the harlequin frog may come in several different colors, always with a bright pattern of blotches on a dark, usually black, background. The bright pattern is often yellow, but may also be another color like green, orange, or red. The frog gets its common name from these colors. A harlequin is a court jester, a person who hundreds of years ago wore gaudy, colorful costumes to entertain an audience.

The frog has very thin but long front legs. Its back legs are a bit thicker and still longer. Its eardrum is not visible. Males grow to about 1.1 to 1.6 inches (2.7 to 4 centimeters) long from snout to rump. The females are larger, reaching 1.3 to 1.9 inches (3.4 to 4.8 centimeters) in length. In some populations, the females and males look much alike, but in others, the males and females come in different colors.

Also known as the harlequin toad, the harlequin frog may come in several different colors, always with a bright pattern of blotches on a dark, usually black, background. The bright pattern is often yellow, but may also be another color like green, orange, or red. (Photograph by Michael Fogden. Bruce Coleman Inc.)

Geographic range: Harlequin frogs live in Costa Rica and Panama in far southern Central America.

Habitat: Harlequin frogs live in moist forests in valleys and partway up the sides of mountains. Scientists have not seen the frogs mating in the wild, but they believe these frogs do so in rocky streams, because this is where they have found harlequin frog tadpoles.

Diet: They eat small arthropods, including spiders and insects, like caterpillars, flies, and ants.

Behavior and reproduction: At night, harlequin frogs sleep on top of large leaves above streams. They are active during the day, hopping about in plain view. Their bright colors help remind predators that the frogs can ooze a very poisonous and bad-tasting liquid from their skin. The poison in the liquid is the same as that found in the very dangerous puffer fish. Males set up territories and make short buzzing sounds to tell other males to stay away. Sometimes, the males will fight by jumping on or chasing one another. They may also circle a front foot in the air before or after a fight. Unlike the males of other frogs, harlequin frog males do not call females for breeding. They do, however, mate like most other frogs with males climbing onto the backs of females. A harlequin frog female may carry a male on her back for several days until she has finished laying her eggs.

Harlequin frogs and people: Humans almost never see this extremely rare frog.

Conservation status: The World Conservation Union (IUCN) has listed this frog as Critically Endangered and facing an extremely high risk of extinction in the wild, because most of them have disappeared since 1988. In 1996, in fact, scientists feared that all of the more than one hundred populations known to exist in Costa Rica were already gone. Seven years later, however, a tiny population was discovered there. Some populations still live in Panama, but their numbers appear to be dropping. Scientists believe that the frogs are mainly disappearing because of infection with a fungus, called chytrid fungus, which is also killing many other frogs worldwide. In addition, people have introduced trout, a popular game fish, to some of the waterways in which the frogs breed. The trout eat harlequin frogs. ∎