Puerto Rican coquis occur in abundance throughout Puerto Rico in terrestrial areas except for the driest regions of the island. They are often found in cohabitation with humans, such as in homes and parks, because of their unrestricted habitat use. Commonly used natural habitats include humid mountain forest at elevations less than 1,200 m and dry forest. Within forests, E. coqui are found at all elevations from the understory to the canopy.
Range elevation: 0 to 1,200 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest
Other Habitat Features: urban ; suburban ; agricultural
Predators of E. coqui include native birds, snakes (Puerto Rican racer, Alsophis portoricensis) as well as large arthropods such as spiders (giant crab spider, Olios sp.). Giant crab spiders will attack and kill E. coqui by jump attack and lethal injection. When threatened, E. coqui juveniles take refuge in the leaf litter and undergrowth on the forest floor. Adult coquis are camouflaged in the foliage of the forest by their markings and sedentary habits.
Known Predators:
Anti-predator Adaptations: cryptic
Eleutherodactylus coqui is described as a small tree frog, however it is the largest frog species in the forests of Puerto Rico, with adults from 24 to 55 mm. Females are larger than males and location also greatly affects size: the higher the elevation, the larger the individual. Both males and females are light brown in color with grey or tan markings on the dorsum and a light gray underside. The toes are individual and non-webbed with large disks on the underside of each toe. These pads contain a sticky surface which allows them to ascend trees and leaves.
Range mass: 54 to 117 g.
Range length: 24 to 55 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Maximum lifespan of E. coqui is not known but individuals have been found in the wild up to 6 years old. An estimated 94% of adult individuals do not live past their first year.
Range lifespan
Status: wild: 6 (high) years.
Typical lifespan
Status: wild: 1 (high) years.
Average lifespan
Status: wild: < 1 years.
Puerto Rican coquis, Eleutherodactylus coqui, are found naturally in Puerto Rico up to elevations of 1,200m. They have been introduced to southern Florida, Hawaii, and the U.S. Virgin Islands.
Biogeographic Regions: nearctic (Introduced ); neotropical (Native ); oceanic islands (Introduced )
Puerto Rican coquis feed primarily on arthropods. Diet varies with size and age but not gender. Smaller, juvenile frogs eat smaller prey, such as ants. Larger frogs have a more diverse diet, including larger organisms such as spiders, moths, crickets, snails and even small frogs. It seems that more than half of the adult coqui’s diet is made up of roaches and crickets and the remaining half is made up of primarily ants, due to their abundance in the forest. Their mode of predation is the energy conserving ambush method. E. coqui individuals will sit on leaves, not moving at all, until the prey is very close, whereupon they strike. They often move less than 5 cm to reach prey in a strike. E. coqui often remain at profitable foraging sites throughout the night.
Animal Foods: amphibians; insects; terrestrial non-insect arthropods; mollusks
Primary Diet: carnivore (Insectivore )
Eleutherodactylus coqui is important to the health of the forest ecosystem. Large invertebrate predators, such as spiders, rely heavily on E. coqui for prey. Birds and snakes also rely on them for consumption. E. coqui functions as a secondary predator, preying on ants and crickets, as well as a tertiary consumer, eating spiders and centipedes.
Because E. coqui are commonly found living in human dominated landscapes, such as in homes and parks, they may function as a live-in pest control agent, removing unwanted insects from human homes.
Positive Impacts: controls pest population
Importation of exotic plant species from Puerto Rico resulted in the introduction of E. coqui to the mainland U.S. as well as Maui and Hawaii Islands. On the Hawaiian Islands, which contain no native frogs, people complain about the disturbance of the “ko-kee” call produced by males at night. There is concern that this disturbance may negatively affect the tourist and real estate industries. The introduction of this exotic species also negatively affects the native species present on the islands, with the potential to severely upset the native population of arthropods as well as native insectivorous bird populations. These frogs also provide a larger prey base for predators of native birds such as rats and mongoose which causes increased pressure on the bird population. Puerto Rican coquis have been shown to affect the nutrient cycling in leaf litter negatively.
Negative Impacts: household pest
Development proceeds from larval form to froglet within the egg. The free-living tadpole stage is bypassed in development, allowing eggs to be laid in the absence of standing water. Clutches of eggs hatch within 8 weeks and reproductive maturity is reached within approximately one year. The genus Eleutherodactylus developes an egg tooth to free the young froglet from the egg.
Development - Life Cycle: metamorphosis
The E. coqui population is currently identified as near threatened based on possible decline in population size which has been witnessed on the island of Puerto Rico in recent years. This is particularly true in the case of populations at higher altitudes. Threats to the population include pollution as well as pathogens such as chytridiomycosis (amphibian fungal disease). Conservation methods are in place for habitat protection but further action needs to be taken in the area of disease control and more complete population monitoring.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Communication is primarily acoustic in E. coqui. Males emit a two part call, the first part, identified as "co", is a defensive and threatening call towards males, the second part or "qui" is the call that attracts females. If a male frog is in the surrounding vicinity the caller ceases the female attracting part of the call, leaving only the threatening "co" part of the call. Females are known to make a low rasping call in defense of feeding territories. Puerto Rican coquis perceive their environment with visual, chemical, tactile, and auditory senses.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
The population size of E. coqui outnumbers all other frogs within the forests of Puerto Rico. The availability of shelter and nesting, when limited, is a factor in the population size of E. coqui. Worldwide, populations have increased as E. coqui have been introduced and established in Florida and the Hawaiian Islands through the importation of greenhouse plants from Puerto Rico.
Males emit a two part call consisting of a "co" which is used when threatened by another male and the "qui" which attracts females . Once a nesting territory is established, males and females fight off intruders by chasing, jump attacks, and sometimes biting. This territorial behavior is exhibited by males as well as females.
Eleutherodactylus coqui reproduce year round, but reproduction rates increase during the rainy season. Fertilization occurs internally in the female and approximately 3-45 eggs are laid in the nest. Clutches are laid approximately every 8 weeks. E. coqui embryos do not emerge as tadpoles, but develop directly into froglets and emerge approximately 17 to 26 days after the eggs are laid. The male remains to guard the nest for many days after froglets hatch. The absence of the tadpole stage allows nesting to occur in dry sites devoid of standing water. Nesting sites occur in protected cavities such as tree holes and the petioles of rolled palms. Abandoned bird nests are also utilized by E. coqui for nesting sites. The bananaquit (Coereba flaveola portoricensis), Puerto Rican bullfinch (Loxigilla portoricensis) and Puerto Rican tody (Todus mexicanus) are all birds which share nests with E. coqui.
Breeding interval: Clutches are laid approximately every 8 weeks throughout the year.
Breeding season: Puerto Rican coquis breed throughout the year and more frequently during the rainy season.
Range number of offspring: 3 to 45.
Average number of offspring: 27.
Range time to hatching: 17 to 26 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Males are primary caretakers of eggs. They offer protection from predators as well as ensure that eggs are moist through contact with their skin. Males will leave the nest during extremely dry periods in order to collect moisture for the egg clutch.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male)
The common coquí or coquí (Eleutherodactylus coqui) is a species of frog endemic to Puerto Rico belonging to the family Eleutherodactylidae. The species is named for the loud call the males make at night. This sound serves two purposes. "CO" serves to repel other males and establish territory while the "KEE" serves to attract females.[2] 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.
The common coquí was described as a species new to science by Richard Thomas in 1966.[3] It belongs to the genus Eleutherodactylus which in Greek means free toes. This family is also known as the "robber" or "thief" frogs. This genus contains 185 species, which are found in the Southern United States, Central America, South America, and the Caribbean. It is part of the order Anura, which includes all frogs and toads. The scientific name of the common coquí, Eleutherodactylus coqui, was first described by Spanish naturalist José Félix de Arroyo de la Cuesta in 1875 (Arroyo de la Cuesta, 1875). The genus Eleutherodactylus, of which the common coquí is a member, is the largest genus of frogs in the world, with over 700 known species. The common coquí is closely related to other members of the Eleutherodactylidae family, including the Eleutherodactylus jasperi and the Eleutherodactylus portoricensis. These species are all native to Puerto Rico and are distinguished from each other by their physical characteristics and vocalizations (Joglar and López, 1997). This taxonomic classification reflects the evolutionary relationships between the common coquí and other species within the animal kingdom.
Full-grown male coquís measure, from snout to vent, from 30 to 37 mm, with an average of 34 mm, while full-grown females measure from 36 to 52 mm, with an average of 41 mm. The location of the frog also effects the size, for example the higher the elevation, the larger the coquis become. The size differences between sexes are a result of additional energy consumption related to breeding behavior by males.[4]
Coquís are muddy-brown in mottled coloration on the top with rust-tan flanks and a light-gray belly. As tree frogs, Coquís possess sticky pads on the tips of their toes which help them adhere to moistened or slippery surfaces[5] They do not possess webbed feet and are not adapted to swimming.
The known lifespan of the common coquí is up to 6 years in the wild, but the majority of adults do not live past one year. It is generally thought that the species has a relatively short lifespan, with most individuals living for less than a year. In a study of the population dynamics of the common coquí, researchers found that the species has a high mortality rate, with only a small proportion of individuals surviving to reach adulthood. This high mortality is likely due to a variety of factors, including predation, disease, and competition for resources.
The common coquis are nocturnal and their behavior is influenced by the surrounding environment, specifically the moisture levels. When humidity levels rise at night they emerge and begin climbing to their homes in the canopy. As these humidity levels decrease they move back down to lower levels where the humidity is higher. The younger coqui populations live in the understory on leaves during the drier periods. The leaves are particularly common with this population because they provide protection from invaders. As they grow into adulthood, the coquis journey up to the canopy and begin the process stated above.[6]
A comparative behavioral study between frog species identified possible explanation for jump and hydration level correlations. The paper, "Water loss, cutaneous resistance, and effects of dehydration on locomotion of Eleutherodactylus frogs," examines the effects of water loss and dehydration on two species of neotropical frogs, the common coquí and the cave coquí (Eleutherodactylus cooki). The researchers found that jumping performance declined with an increase in water loss and a longer duration of exposure to dehydrating conditions. The common coquí, which occupies a wider range of habitats, including dry forests, had a slightly higher rate of water loss and lower cutaneous resistance than the cave coquí. However, these differences were not significant enough to explain the different geographic distributions of the two species. The study suggests that behavioral adaptations, rather than physiological differences, may play a role in the common coquí's ability to survive in drier habitats.[7]
Common coquís are native to the islands of Puerto Rico, Vieques and Culebra, where they are widespread and abundant; the only notable exception occurs in Puerto Rican dry forests, where the species is rarer. The common coquí is the most abundant frog in Puerto Rico, with densities estimated at 20,000 individuals/ha.[8] 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.[9] The species is considered a habitat generalist, occurring in a wide range of habitats, including mesic broadleaf forests, mountains, and urban areas, found in bromeliads, tree holes, and under trunks, rocks or trash.[10] Since the species does not require bodies of water to reproduce, they can be found on most altitudes, provided sufficient moisture is available. In Puerto Rico, they are found from sea level to a maximum of 1,200 m (3,900 ft). Adults generally tend to be found at higher altitudes than juveniles.
The common coquís are often found in cohabitation with humans. Because of their unrestricted habitat use, E. coquí can commonly be found in homes and parks. E. coquí are found in natural habitats including the human mountain forest at elevations less than 1,200 meters and in the dry forest. They are found specifically within the under story of forests at all elevations up to the canopy.[11]
The species has been introduced to Colombia,[12] Hawaii in the United States, and the Virgin Islands.[13][14] It has become a densely populated invasive species in the Hawaiian Islands, where it was accidentally introduced in the late 1980s, most likely as a stowaway on potted plants, and quickly established itself on all four major islands. It is now considered a pest species by the State of Hawaii,[15] and is on a list of 100 of the world's worst invasive alien species.[16] As an invasive species, it can reach up to 91,000 individuals/ha, almost 5 times its maximum density in its native Puerto Rico.[17] Higher densities in its invaded range are likely bolstered by a release from native predators, lack of interspecific competitors, and abundant food availability. In Hawaii, they have been found at a maximum of 1,170 m (3,840 ft) above sea level.[18] They were previously introduced in the Dominican Republic[19] and to Louisiana and Florida, but these populations have now been eradicated.
Common coquís in areas where their density exceeds 51,000/ha could consume over 300,000 invertebrates per night. Because of their large populations, Hawaii worries about both economic and ecological impacts. The common coquí currently costs this state nearly 3 million dollars a year. Its spread has been commonly through the nursery trade, and as a result many people are reluctant to buy plants from nurseries that might be infected. Those began to perform quarantines and de-infestations in order to improve their prospects. Coquis also affect real estate values in residential neighborhoods, as many refrain from buying houses where their sleep would be disturbed by the up to 73 dB call of the common coquí.[20]
Invasive management practices against the common coquí frog aim to control and reduce the population of this species in areas where it has been introduced, such as Hawaii. Preventative measures include banning the intentional transport of frogs, as well as the implementation of hot-water shower treatments on ornamental plants to kill coquí eggs, subadults, and adults. This can reduce the potential spread of the species through the trade of plants. Physical control methods, such as hand-capture, can be effective for small populations of common coquí frogs. Chemical control methods, such as the use of caffeine and water solutions, are also being tested for their efficacy in controlling the species on a larger scale. Citric acid has also been suggested as a potential control method, although its efficacy has not been demonstrated. Overall, a variety of management practices are being explored and implemented in order to control and reduce the population of common coquí frogs in invaded areas.[21]
The common coquí is a generalist nocturnal predator, which can consume, as a population, 114,000 invertebrates each night per hectare.[8] Diets vary depending on age and size, but are primarily composed of arthropods. Juveniles consume smaller prey, such as ants, while adults consume more varied diets that include spiders, moths, crickets, snails, and small frogs.[8] The frogs are opportunistic sit-and-wait predators, and will forage on any abundant prey items. Males will occasionally consume eggs from their own clutch, likely to provide supplemental nourishment while guarding their nests.
Calling males eat less prey than quiet males, which consume most of their food by midnight, while calling males had eaten only 18% of their food by the same hour.[22]
Common coquís reproduce over the entire year, but breeding activity peaks around the wet season. Females usually lay between 16 and 40 eggs, four to six times each year, at about eight-week intervals. Eggs are guarded from predators—other common coquís and Subulina snails—by the males.[4] The gestation period of coquís is from 17 to 26 days. The maturation period, the time from egg to reproductive coquí, is around eight months.
Unlike most 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.[18] 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. Eggs hatch within eight weeks and reach reproductive maturity within one year. The common coqui releases their young from the egg using an egg tooth that the genus Eleutherodactylus forms. Both males and females fight off intruders from their nests by jumping, chasing and sometimes biting. The males are the primary caretakers of the eggs. They offer protection and moist environments through skin contact. They will leave during very dry periods in order to collect more moisture for their offspring.[23]
Males begin their mating calls by perching above ground level.[24]
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".
The common coquí or coquí (Eleutherodactylus coqui) is a species of frog endemic to Puerto Rico belonging to the family Eleutherodactylidae. The species is named for the loud call the males make at night. This sound serves two purposes. "CO" serves to repel other males and establish territory while the "KEE" serves to attract females. 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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