| Coquí | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Domain: | Eukaryotic |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Amphibia |
| Order: | Anura |
| Family: | Leptodactylidae |
| Subfamily: | Eleutherodactylinae |
| Genus: | Eleutherodactylus |
| Subgenus: | Eleutherodactylus[2] |
| Species: | E. coqui |
| Binomial name | |
| Eleutherodactylus coqui Thomas, 1966 |
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The Common Coquí or Coquí (Eleutherodactylus coqui) is a frog native to Puerto Rico belonging to the Eleutherodactylus genus of the Leptodactylidae family. The species is named for the loud call the males make at night. This sound serves two purposes. 'CO' serves to repel males and establish territory while the 'QUI' serves to attract females[3]. Since the auditory systems of males and females respond preferentially to different notes of the male call, this is an example of a sex difference in a sensory system. The Common Coquí is a very important aspect of Puerto Rican culture and it has become an unofficial territorial symbol of Puerto Rico.
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The Common Coquí was described by R. Thomas in 1966[4]. It belongs to the Eleutherodactylus genus which in Greek means free toes. The Eleutherodactylus genus contains 185 species which are found in the south of the United States, Central America, South America and the Caribbean.
Fully grown male coquís measure, from snout to vent, from 30 to 37 mm with an average of 34 mm, while fully grown females measure from 36 to 52 mm with an average of 41 mm. The size differences between genders are a result of additional energy consumption related to breeding behavior by males.[5]
Contrary to popular belief and artistic renditions, which depict the species as green, coquís commonly have a gray or gray-brown coloration. Unlike many frogs, coquís do not possess swimming membranes between their fingers and toes, and thus are not adapted to swim. However, like all tree frogs they possess small pads on the tips of their toes which help them adhere to moistened or slippery surfaces.
Common Coquís are native to the islands of Puerto Rico, Vieques and Culebra where they are widespread and abundant; the only notable exception occurring in Puerto Rican dry forests where the species is rarer. The species has been introduced to the Virgin Islands, the Dominican Republic,[6] Florida, and Hawaii,[7] where it has become a densely populated invasive species. It was accidentally introduced to the Hawaiian Islands in the late 1980s, and quickly established itself on all four major islands. It is now considered a pest species by the State of Hawaii, and is on the list of the world's 100 worst invasive alien species.[8]
The Common Coquí is the most abundant frog in Puerto Rico with densities estimated at 20,000 individuals/ha,[9] and as an invasive species can reach up to 91,000 individuals/ha in Hawaii.[10] Higher densities in its invaded range are likely bolstered by a release from native predators, lack of interspecific competitors, and abundant food availability. Densities fluctuate depending on the season and habitat. Generally, densities are higher during the latter half of the wet season and decrease during the dry season.[11]
The species is considered a habitat generalist, occurring in a wide range of habitats including mesic broadleaf forests, mountains, urban areas, bromeliads, tree holes, and under trunks, rocks or trash.[12] Since the species does not require bodies of water to reproduce, they can be found on most altitudes provided there is sufficient moisture. In Puerto Rico they are found from sea level to a maximum of 1,200 metres (3,900 ft) while in Hawaii they have been found at a maximum of 1,170 metres (3,840 ft).[13] Adults generally tend to be found at higher altitudes than juveniles.
The Common Coquí is a general nocturnal predator which can consume, as a population, 114,000 invertebrates each night per hectare.[9] Diet varies depend on age and size but is primarily composed of arthropods. Juveniles consume smaller prey such as ants while adults consume a more varied diet that includes spiders, moths, crickets, snails, and small frogs.[9] The frogs are opportunistic sit-and-wait predators and will forage on abundant prey items. Males will occasionally consume eggs from their own clutch, likely to provide supplemental nourishment while guarding their nest.
Calling males eat less prey than non-calling males. A study found that non-calling males consume most of their food by 2400 h while calling males had eaten only 18% of their food by the same hour.[14]
Common Coquís reproduce over the entire year but breeding activity peaks around the wet season. Females usually lay between 16 and 40 eggs from 4-6 times each year at approximately 8-week intervals. Eggs are guarded from predators—other common coquís, Subulina snails—by males.[5] The gestation period of coquís is from 17–26 days. The maturation period, the time from egg to reproductive coquí, is around eight months.
Contrary to many frogs, which lay their eggs in water, coquís lay their eggs on palm tree leaves or other terrestrial plants. Abandoned bird nests are also used as nests by E. coqui. The Bananaquit, Puerto Rican Bullfinch and Puerto Rican Tody share nests with the coquí.[13] This method of reproduction allows the coquí to live in forests, mountains and other habitats without direct dependency on water. Since eggs are laid on land, coquís bypass the tadpole stage, proceeding to develop limbs within their eggs, rather than going through a metamorphosis as a larva in water. Thus, a fully independent froglet emerges from the egg, with a small tail that is lost shortly after. This stage of direct development has allowed the coqui to become a successful terrestrial colonizer in tropical areas.
Males begin their mating call by perching above ground level.[15]
| External audio | |
|---|---|
| Coqui's distinct calls may be heard here, and here. | |
The coqui's call (or canto in Spanish) is used both as a way of attracting a mate and to establish a territorial boundary. A coqui may enter another's territory and challenge the incumbent by starting his call at which point they may engage in a sort of singing duel (which can last for several minutes). The first to falter in keeping up with the cadence is considered the loser and leaves the area without resorting to physical violence. This behavior is consistent across different species (which have distinctive calls); so it is possible to hear a duel where one coqui sings "COQUI" and another "COQUIRIQUI".