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Eleutherodactylus coquiCommon Coqui(Also: Coqui)

By Katy Maiorana

Geographic Range

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. ("Amphibians", 2003)

Habitat

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. ("Amphibians", 2003; Stewart and Woolbright, 1996)

  • Range elevation
    0 to 1,200 m
    0.00 to ft

Physical Description

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. ("Invasive Species Database", 2005; Stewart and Woolbright, 1996)

  • Sexual Dimorphism
  • female larger
  • Range mass
    54 to 117 g
    1.90 to 4.12 oz
  • Range length
    24 to 55 mm
    0.94 to 2.17 in

Development

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. ("Invasive Species Database", 2005; "Invasive Species Database", 2005; Fogarty and Vilella, 2002)

Reproduction

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. ("Invasive Species Database", 2005; Fogarty and Vilella, 2002; Parsons, 2000)

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. (Schwartz and Henderson, 1991; "Invasive Species Database", 2005; Schwartz and Henderson, 1991)

  • 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

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. ("Invasive Species Database", 2005)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • male

Lifespan/Longevity

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. (Stewart and Woolbright, 1996)

  • Range lifespan
    Status: wild
    6 (high) years
  • Typical lifespan
    Status: wild
    1 (high) years
  • Average lifespan
    Status: wild
    < 1 years

Behavior

Eleutherodactylus coqui is a nocturnal tree climber. Behavior is heavily influenced by moisture levels in the surrounding environment especially in the juvenile population, which is likely to remain in the leaf litter of the understory during particularly dry periods. Leaf litter also provides protection from predators for juvenile coquis. Juvenile coquis begin their life in the understory. As they grow in size they venture further up into the canopy of the forest. Non-breeding females primarily forage in the canopy and breeding males and females are generally found in areas surrounding nesting and calling sites in the understory and sometimes in the canopy if an appropriate site can be found. Puerto Rican coquis emerge at night when the humidity level increases and climb to the canopy to forage. As the humidity level drops in morning, they descend to the lower levels of the forest, where humidity is higher. ("Eleutherodactylus coqui", 2002; Stewart and Woolbright, 1996)

Home Range

Within the forest, E. coqui inhabits a home range extending vertically from the understory to the canopy. Horizontal movement does not often exceed 6 m a night. Range is influenced in part by moisture levels of the surrounding environment. The population size of the E. coqui outnumbers all other frogs within the forests of Puerto Rico. Distribution of E. coqui falls between 8-25 adult individuals/100m^2 during the wet season and 3-29 adult individuals/100 m^2 during the dry season. ("Amphibians", 2003; Fogarty and Vilella, 2002; Stewart and Woolbright, 1996)

Communication and Perception

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. (Parsons, 2000; Schwartz and Henderson, 1991)

Food Habits

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. ("Invasive Species Database", 2005; Duellman and Trueb, 1986; Stewart and Woolbright, 1996)

  • Animal Foods
  • amphibians
  • insects
  • terrestrial non-insect arthropods
  • mollusks

Predation

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. ("Invasive Species Database", 2005; Duellman and Trueb, 1986; Stewart and Woolbright, 1996)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

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. (Stewart and Woolbright, 1996)

Economic Importance for Humans: Positive

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. ("Gulf States Marine Fishery Commission", 1999)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

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. ("Gulf States Marine Fishery Commission", 1999; "Invasive Species Database", 2005; Krauss, 1999)

  • Negative Impacts
  • household pest

Conservation Status

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. (Hedges, et al., 2004)

Other Comments

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. ("Amphibians", 2003; Fogarty and Vilella, 2002; Parsons, 2000; Stewart and Woolbright, 1996)

Contributors

Tanya Dewey (), Animal Diversity Web.

Katy Maiorana (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

References

2003. Amphibians. Pp. "164" in M Hutchins, W Duellman, N Schlager, eds. Grzimek's Animal Life Encyclopedia, Vol. 6, Second Edition. Farmington Hills, MI: Gale Group.

2002. Eleutherodactylus coqui. Pp. "90" in T Halliday, K Adler, eds. The Firefly encyclopedia of reptiles and amphibians, Vol. 1, First Edition. Buffalo: Firefly Books.

1999. "Gulf States Marine Fishery Commission" (On-line). Eleutherodactylus coqui (Thomas). Accessed October 08, 2005 at http://nis.gsmfc.org/nis_factsheet.php?toc_id=204.

2005. "Invasive Species Database" (On-line). National Biological Information Infrastructure (NBII) and Invasive Species Specialist Group (ISSG). Accessed October 16, 2005 at http://www.issg.org/database/species/ecology.asp?si=105&fr=1&sts=.

Duellman, W., L. Trueb. 1986. Biology of Amphibians. New York: McGraw Hill Book Company.

Fogarty, J., F. Vilella. 2002. Population dynamics of Eleutherodactylus coqui in Codillera Forest Reserves of Puerto Rico. Journal of Herpetology, 36: "193-201".

Hedges, B., R. Joglar, R. Thomas, R. Powell. 2004. "Eleutherodactylus coqui" (On-line).

IUCN Red List of Threatened Species
. Accessed October 16, 2005 at http://www.redlist.org/search/details.php?species=56522.

Krauss, F. 1999. "Coqui & greenhouse frogs: Alien Caribbean frogs in Hawaii" (On-line). Hawaii Ecosystems at Risk Project. Accessed October 06, 2005 at http://www.hear.org/AlienSpeciesInHawaii/species/frogs/index.html.

Parsons, H. 2000. The Nature of Frogs: Amphibians with attitude. Vancouver: Greystone Books.

Schwartz, A., R. Henderson. 1991. Amphibians and Reptiles of the West Indies: Descriptions, Distributions and Natural History. Gainesville: University of Florida Press.

Stewart, M., L. Woolbright. 1996. Amphibians. Pp. "274-320" in D Reagan, R Waide, eds. The Food Web of a Tropical Rain Forest. Chicago: The University of Chicago Press.

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