The coqui frog, a tropical tree frog, produces a distinct two-note croak that sounds just like its name "ko-kee."
The lower "ko" sound is a warning to other male frogs telling them to keep their distance. Only males listen and
respond to "ko." The female coqui frogs listen to the higher-pitched "kee" note. When male frogs hear
territorial calls from nearby male coqui frogs, they will drop the "kee" part of their call and concentrate on "ko"
until individual frogs are spaced out to everyone's satisfaction. Then the coquis call to the female frogs with the higher-pitched
The coqui name generally applies to all 16 species of frogs in Puerto Rico. Thirteen of these live in El Yunque--11 are only
in Puerto Rico. The coqui sound of "ko-kee" actually comes from only two of the frog species, the Forest (el Coquí
de la Montaña) and Common Coqui (el Coquí Común). Each of the other species has its own distinct call.
The Burrow Coqui, el Coquí Duende, can be found only in the Dwarf Forest of El Yunque. Coquis vary in color from green
to yellow to gray to brown and range in size from 15 mm in length, (Burrow Coqui), to 80 mm in length,(web-footed Coqui).
Three of all 16 species of the coquis are highly endangered. The Web-footed Coqui,the Mottled Coqui, and the Golden Coqui,
are classified as threatened or extinct in Puerto Rico. The Golden Coqui is the rarest and considered extinct by many experts.
Coquis do not start out in life as tadpoles but as baby versions of their parents. The female lays approximately 28
eggs. In at least five of the species, the male forces the female away soon after laying--then broods and guards the eggs
till they hatch.
Coquis sing out to protect their territories: feeding, mating, and shelter. The loudest calls are emitted by the male
coquis telling others to stay away. The sound embeds itself into the minds of the locals and never leaveseven after they have
left the island. After being away from the island, the sound can bring back found memories and even a tear to displaced Puerto
Sixteen species of tree frogs from the genus Eleutherodactylus are currently known within Puerto Rico, 13 of them are known
to inhabit the rain forest.
E. Hedricki was discovered in 1962 and named in honor of Hedrick J. Rivero. At age 9, Hendrick became the assistant to
his father and followed him throught the rain forest.
E. Hedricki has a pronounced constriction in the back of the head, a shallow furrow along the middle of the back from
between the eyes to near the sacral hump, and the short rounded snout. Other distinguishing but not necessarily exclusive
characteristics are: the small eyes, with narrow upper eyelids, the uniformerly granular dorsum, the pair of light, externally
concave lines on the back (not too distinct in very dark animals), the blackish throat of males, and the absence of dark streaks
along the sides of the snout. The basic dorsal color may be brown or dark gray, almost uniform or with obscure variegation
or vermiculations of lighter gray. The males averages 32.8 mm in size, while females averages 34.6.
In general, it is one of the mountain arboreal species that rest in and calls from holes and crevices in tree trunks and
branches, often as high 20 or 30 ft. from ground.
The sound of E. hedricki is a resonant "ping, ping, ping" that may be heard during the day time but by midnight
most of the callers have become silent. The voice has not been heard below about 1,000 ft.