Eleutherodactylus coqui (Caribbean tree frog)
- Summary of Invasiveness
- Taxonomic Tree
- Distribution Table
- Habitat List
- Biology and Ecology
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Principal Source
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Eleutherodactylus coqui (Thomas, 1966)
Preferred Common Name
- Caribbean tree frog
International Common Names
- English: common coqui; Puerto Rican treefrog
Local Common Names
- Germany: Coqui
Summary of InvasivenessTop of page
E. coqui is a relatively small tree frog native to Puerto Rico, which has been introduced to Florida, Hawaii, the Galapagos Islands, New Zealand and a few other Caribbean islands. The frogs are quite adaptable to different ecological zones and elevations. Their loud call is one of the main reasons they are considered a pest; E. coqui's mating call is its namesake - a high-pitched, two-note "co-qui" (‘ko-kee') which attains nearly 100 decibels when measured at a distance of 0.5 metres. E. coqui has a voracious appetite and there is concern in Hawai‘i that it may put endemic insect and spider species at risk and compete with endemic birds and other native fauna which rely on insects for food.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Chordata
- Subphylum: Vertebrata
- Class: Amphibia
- Order: Anura
- Family: Leptodactylidae
- Genus: Eleutherodactylus
- Species: Eleutherodactylus coqui
DescriptionTop of page
E. coqui is described as a relatively small tree frog. In Puerto Rico, mature calling males and "parental males" (males guarding a clutch) average about 34mm in length from snout to vent (snout-vent length, or SVL), while mature egg-laying females average about 41mm SVL. Like the true tree frogs (family Hylidae), E. coqui have well developed pads at the end of each toe that are used for sticking to surfaces. E. coqui individuals are extremely variable in colouration. The dorsum (upper surface) is generally grey or grey-brown and may be uniform in colour. Alternatively, they may have either a dark "M" shape between the shoulders, two broad, light dorso-lateral bars (from the snout, through to the eye, to the axilla of the rear legs) bordered with black spots and/or a light bar on top of the head between the eyes and a light underside stippled with brown (Campbell, 2000). For further descriptions and pictures of different morphs see the report on E. coqui in ‘Biology and Impacts of Pacific Island Invasive Species’ (Beard et al., 2009).
DistributionTop of page
Native range: South America: Puerto Rico (Beard et al. 2003).
Known introduced range: Australasia-Pacific, North America (USGS-NAS, 2004), Galapagos Islands (Snell and Rea, 1999).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|USA||Present||Present based on regional distribution.|
|-Hawaii||Restricted distribution||Introduced||Between 1988 and 1992||Invasive||ISSG, 2011||A serious problem on the Big Island and Maui. A population on O'ahu was successfully eradicated.|
Central America and Caribbean
|Dominican Republic||Present||Introduced||Invasive||ISSG, 2011|
|Puerto Rico||Present||Native||Not invasive||ISSG, 2011|
|United States Virgin Islands||Present||Introduced||Invasive||ISSG, 2011|
|Ecuador||Present||Present based on regional distribution.|
|-Galapagos Islands||Present||Introduced||ISSG, 2011|
|Guam||Absent, intercepted only||Introduced||2004||ISSG, 2011|
|New Zealand||Present||Introduced||ISSG, 2011|
HabitatTop of page
E. coqui has been described as a habitat generalist. Quantitative studies on habitat preferences of E. coqui in its native range have shown that different individuals preferred different heights from the forest floor. Adults were seen to have a wider preference for a range of heights compared with juveniles. Adults have demonstrated a strong positive association with dead, fallen leaves and early successional species, such as Cecropia, Heliconia and Prestoea. E. coqui generally have positive associations with shrubs and negative associations with grasses, vines and ferns. Exceptions include Philodendron angustatum and Danea nodosa, which both have a broad leaf structure and are thus able to provide better structural support than other species in those habitat categories (Beard et al. 2003). Kraus and Campbell (2002) report evidence that the ecological range of E. coqui in Hawai‘i has continued to expand. Initially the frogs were reported from relatively low elevations (0–670m). Subsequent studies show that a large population has survived and overwintered at 920m elevation. Four other populations have survived two winters at elevations of 1170m. In its native Puerto Rico, E. coqui occurs up to elevations of 1200m.
Habitat ListTop of page
|Cultivated / agricultural land||Present, no further details||Harmful (pest or invasive)|
|Managed forests, plantations and orchards||Present, no further details||Harmful (pest or invasive)|
|Urban / peri-urban areas||Present, no further details||Harmful (pest or invasive)|
|Natural forests||Present, no further details||Harmful (pest or invasive)|
|Riverbanks||Present, no further details||Harmful (pest or invasive)|
|Wetlands||Present, no further details||Harmful (pest or invasive)|
Biology and EcologyTop of page
E. coqui is a generalist nocturnal predator and consumes an estimated 114, 000 invertebrates per hectare per night (Stewart & Woolbright, 1996) and even more at its highest densities in Hawai'i. It consumes invertebrates mostly on vegetation at night and in the litter during the day (Beard, 2007).
E. coqui reproduce year-round in their native range, but breeding activity is concentrated in the wet season. Female E. coqui lay 4-6 clutches of about 28 eggs each (range 16-41) per year. The time period between clutches is around eight weeks. E. coqui utilize internal fertilization and, like other eleutherodactylids, the fertilized eggs undergo direct development, rather than passing through a free-living larval (tadpole) stage, so standing water is not required for egg laying. E. coqui are known to utilize the nesting cavities of several bird species in Puerto Rico, including the bananaquit (Coereba flaveola portoricensis), the Puerto Rican bullfinch (Loxigilla portoricensis) and the Puerto Rican tody (Todus mexicanus). Male frogs nest in protected cavities near the ground, such as dead, curled leaves or rolled palm frond petioles. Males, which guard the eggs (to keep them from drying out), are known to leave the nest in severely dry conditions to gather moisture to rehydrate the eggs (Campbell, 2000).
E. coqui utilize internal fertilisation and, like other eleutherodactylids, the fertilized egg undergoes direct development, rather than passing through a free-living larval (tadpole) stage, so standing water is not required for egg laying. The time period between clutches is around eight weeks (Campbell, 2000).
Notes on Natural EnemiesTop of page
E. coqui forms part of the diets of birds and nocturnal mammals. They are known to be eaten by the giant crab spiders, Olios spp. and the Puerto Rican racer (a snake), Alsophis portoricensis.
E. coqui is relatively resistant to the chytrid fungus Batrachochytrium dendrobatidis
Means of Movement and DispersalTop of page
Nursery trade: E. coqui was accidentally introduced in a shipment of nursery plants to Hawai'i in the late 1980s (Beard, 2006). It is thought to have entered Guam through the horticultural trade (Christy et al., 2007).
Local dispersal: Because the coqui has direct development (no tadpole phase), it was able to spread quickly, especially on the islands of Hawaii and Maui, where there are now hundreds of populations (Beard et al., 2006).
Pathway VectorsTop of page
|Plants or parts of plants||Yes||Yes|
Impact SummaryTop of page
ImpactTop of page
In Hawai‘i the population can reach extremely high densities of up to 91,000 frogs per hectare, far exceeding those in its native range (Beard et al., 2009). In areas where E. coqui reach >50, 000 per hectare, it is estimated that they can consume around 350,000 invertebrate prey items per hectare per night. Studies have shown that E. coqui can impact upon invertebrate communities in Hawai‘i, for example, reducing both non-native and endemic native invertebrates (Choi et al., 2012; Beard et al., 2008). There is concern that it could compete with native insectivorous bird species. E. coqui can also affect ecosystem processes. For example it has the potential to increase foliage production rates, and nutrient cycling rates (Beard et al., 2008; Beard et al., 2003). This may provide a competitive advantage to invasive plants in Hawai‘i where native species have evolved in nutrient-poor conditions (Sin et al., 2008).In Hawai‘i there are concerns over economic impacts as well as ecological impacts (Beard et al., 2009). The cost of current E. coqui detection and control on Hawai‘i alone is $2.8 million annually. An important pathway for spread has been through the nursery trade. Quarantine restrictions and de-infestation measures are costing the nursery and floriculture industries, and customers may be more reluctant to buy due to concerns of infestation (Beard, 2006). E. coqui have spread from horticultural sites where they were first restricted, to public land, residential areas and resorts. There are concerns that property value may be affected due to the high biomass of frogs on infested sites (Kraus and Campbell, 2002). The high pitched call of the frog is a disturbance and there are fears this may affect the tourism industry (HEAR, 2004). Real estate prices have been negatively affected in heavily infested areas.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Ecosystem change/ habitat alteration
- Modification of nutrient regime
- Negatively impacts tourism
- Reduced amenity values
- Reduced native biodiversity
- Threat to/ loss of native species
- Negatively impacts trade/international relations
- Competition - monopolizing resources
- Highly likely to be transported internationally accidentally
UsesTop of page
In its native Puerto Rico, E. coqui is considered a national symbol, and appears extensively on tourist items (Beard et al., 2009).
Similarities to Other Species/ConditionsTop of page
Two external characters serve to readily differentiate E. martinicensis from E. coqui: firstly E. martinicensis has digital discs with a smoothly rounded anterior margin, whereas E. coqui has digital discs with a straight anterior margin; and secondly E. martinicensis has a distinct white chevron above the anus, which E. coqui lacks (Kraus and Campbell 2002).
Prevention and ControlTop of page
Physical: Hand-capture is a successful method when dealing with small numbers (Kraus and Campbell, 2002). Because usually only adult males call, locating females and egg masses is challenging (Beard et al., 2009). Another physical approach is habitat modification – this involves clearing of understorey vegetation in order to reduce the number of potential nesting and retreat sites (Beachy et al., 2011).
Non-chemical: A study by Hara et al. (2010) showed that a hot-water shower treatment of ornamental plants in commercial nurseries is an effective disinfestation treatment for E. coqui eggs, subadults and adults; thus reducing one major potential pathway for the spread of this species. It is recommended that ornamental plants be treated to a 45° C shower for up to 5 minutes, as this regime is sufficient to achieve mortality of all stages of the frog while being within the tolerance range of many of the host plants. This method would be most effective in enclosed areas before transportation of ornamental plants. (Hara et al. 2010). Orchids and bromeliads are sensitive to these heat treatments (Beard et al., 2009).
Chemical: Citric acid, caffeine and hydrated lime have been used to control E. coqui, however, according to Beard et al. (2009) citric acid is the only chemical currently used legally in Hawai‘i. Endosulfan-based pesticides can only be used in greenhouses and must be applied by a certified pesticide applicator. Spraying citric acid on infested plants to kill E. coqui eggs, juveniles and adults is a recommended option (College of Tropical Agriculture and Human Resources, undated). Aerial citric acid application of concentrations as little as 11% have been shown to reduce E. coqui density - multiple aerial sprays over a frog-infested landscape has been suggested as a control strategy (Tuttle et al., 2008). To be effective, citric acid must contact the frog directly and repeated applications may be required. Citric acid may lead to spots on leaves in some cases.
A successful eradication effort has been conducted on the Hawaiian island of O‘ahu, where there was just a single population. The eradication was a success because the population was small, and the project was well supported and funded. Citric acid was used as well as habitat modification (Beachy et al., 2011).Control efforts may not always be supported by the public. There have been protests based on ethical concerns that have interfered with control attempts. Some find it difficult to believe that a small frog could represent a major threat; also at a time when amphibian populations are declining globally, the idea of eradicating an amphibian is incongruent (Beard et al., 2009).
BibliographyTop of page
Beard KH, Pitt WC, Price EA, 2009. Biology and Impacts of Pacific Island Invasive Species. 5. Eleutherodactylus coqui, the Coqui Frog (Anura: Leptodactylidae). USDA National Wildlife Research Center - Staff Publications. Paper 864. http://digitalcommons.unl.edu/icwdm_usdanwrc/864
References from GISD
Beard, K. H., A. K. Eschtruth, K. A. Vogt, D. J. Vogt, and F. N. Scatena. 2003. The effects of the frog Eleutherodactylus coqui on invertebrates and ecosystem processes at two scales in the Luquillo Experimental Forest, Puerto Rico. Journal of Tropical Ecology 19: 607-617.
Beard, K. H., S. McCullough, and A. K. Eschtruth. 2003. Quantitative Assessment of Habitat Preferences for the Puerto Rican Terrestrial Frog, Eleutherodactylus coqui. Journal of Herpetology 37(1): 10-17.
Beckham, Y. M., K. Nath., and R. P. Elinson. 2003. Localization of RNAs in oocytes of Eleutherodactylus coqui, a direct developing frog, differs from Xenopus laevis. Evolution and Development 5(6): 562-571.
Bomford, M., 2003. Risk Assessment for the Import and Keeping of Exotic Vertebrates in Australia. Bureau of Rural Sciences, Canberra. http://www.feral.org.au/feral_documents/PC12803.pdf
Campbell, E. W.; F. Kraus, S. Joe, L. Oberhofer, R. Sugihara, D. Lease, and P. Krushelnycky., 2002. Introduced Neotropical tree frogs in the Hawaiian Islands: Control technique development and population status. In Turning the tide: the eradication of invasive species: 406 - 414. IUCN SSC Invasive Species Specialist Group. IUCN. Gland. Switzerland and Cambridge. UK.
Campbell, E.W., and F. Kraus. 2002. Neotropical frogs in Hawaii: status and management options for an unusual introduced pest. Pp. 316-318 in Timm, R.M., and R.H. Schmidt (eds.), Proceedings of the 20th Vertebrate Pest Conference. Univ. of California Press, Davis, California.
Campbell, T. S. 2000. The Puerto Rican Coqui (Eleutherodactylus coqui Thomas 1966). The Institute for Biological Invasions. http://invasions.bio.utk.edu/invaders/coqui.html
Centre for Environment, Fisheries & Aquaculture Science (CEFAS)., 2008. Decision support tools-Identifying potentially invasive non-native marine and freshwater species: fish, invertebrates, amphibians. http://www.cefas.co.uk/projects/risks-and-impacts-of-non-native-species/decision-support-tools.aspx
Christy, M.T., C.S. Clark, D.E. Gee II, D.L. Vice, D.S. Vice, M.P. Warner, C.L. Tyrell, G.H. Rodda, J.A. Savidge. Recent Records of Alien Anurans on the Pacific Island of Guam. Pacific Science in press.
College of Tropical Agriculture and human Resources (CTAHR). UNDATED. Control of Coqui Frogs in Hawai'i. University of Hawai'i at Manoa. http://www.ctahr.hawaii.edu/coqui/background.asp
Eldredge, L.G. 1988. Case studies of the impacts of introduced animal species on renewable resources in the U.S.-affiliated Pacific Islands. in B.D. Smith, ed. Topic reviews on insular development in the U.S.-affiliated Islands. Univ. Guam Marine Lab Techincal Report 88, pp 26-46.
Gee II, David E., pers. comm. 2006. Wildlife Biologist, Guam Division of Aquatic & Wildlife Resources and Guam team member of the Pacific Invasives Learning Network (PILN).
Gulf States Marine Fisheries Commission (GSMFC), 2003. Eleutherodactylus coqui (Thomas). University of Southern Mississippi/College of Marine Sciences/Gulf Coast Research Laboratory. http://nis.gsmfc.org/nis_factsheet.php?toc_id=204
Hawaiian Ecosystems at Risk Project (HEAR), 2004. Alien Caribbean Frogs in Hawaii, Problematic frogs trouble people, environment. http://www.hear.org/AlienSpeciesInHawaii/species/frogs/
IUCN, Conservation International, and NatureServe. 2006. Global Amphibian Assessment. Downloaded on 4 May 2006. http://www.globalamphibians.org/
Kaiser, B., and K. Burnett. 2006. Economic Impacts of E. coqui frogs in Hawaii. Interdisciplinary Environmental Review 8:1-11. http://homepage.mac.com/ondinebak/HI_Research1_files/KaiserBurnettCoqui.pdf
Kraus, F., and E. Campbell. 2002. Human-mediated escalation of a formerly eradicable problem: The invasion of Caribbean frogs in the Hawaiian Islands. Biological Invasions 4(3): 327-332
Kraus, F., E. W. Campbell, A. Allison, AND T. Pratt. 1999. Eleutherodactylus frog introductions to Hawaii. Herpetological Review 30:21–25.
Louis A. Somma. 2008. Eleutherodactylus coqui. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=60
Low T, 1999. Feral Future: the Untold Story of Australia’s Exotic Invaders. Viking Press/Penguin Books Australia Ltd, Ringwood, Victoria, Australia, 380 pp
McCoid, M.J. 1993. The “new” herpetofauna of Guam, Mariana Islands. Herpetological Review 24:16-17.
Snell H and Rea S, 1999. The 1997–98 El Ni˜no in Gal´apagos: can 34 years of data estimate 120 years of pattern? Noticias de Gal´apagos 60: 11–20
Stewart, M. M., and L. L. Woolbright. 1996. Amphibians.In D. P. Reagan and R. B. Waide (eds.), The Food Web of a Tropical Rain Forest, pp. 363– 398. Univ. of Chicago Press, Chicago.
Wiles, G.J. 2000. Recent record of reptiles and amphibians accidentally transported to Guam, Mariana Islands. Micronesica 32: 285-287.
Woolbright, 1996. Disturbance influences long-term population patterns in the Puerto Rican frog, Eleutherodactylus coqui (Anura: Leptodactylidae). Biotropica 28:493–501.
ReferencesTop of page
Beachy JR; Neville R; Arnott C, 2011. Successful control of an incipient invasive amphibian: Eleutherodactylus coqui on O'ahu, Hawai'i. Pp. 140-147. In: Veitch CR, Clout MN, Towns DR. (eds). Island invasives: eradication and management.
Beard KH, 2006. Case Study Box: Puerto Rico and Hawaii: Wet tropical forests and the dilemma of coqui frog conservation and eradication. Pp: 135-137. In: Vogt KA, Honea J, Vogt DJ, Andreu M, Edmonds R, Berry J, Sigurdardóttir R, Patel-Weynand T. (eds.). Forests and Society: Sustainability and life cycles of forests in human landscapes.
Beard KH; Pitt WC; Price EA, 2009. Biology and Impacts of Pacific Island Invasive Species. Eleutherodactylus coqui, the Coqui Frog (Anura: Leptodactylidae). USDA National Wildlife Research Center - Staff Publications. Paper 864.
Marr SR; Mautz WJ; Hara AH, 2008. Parasite loss and introduced species: a comparison of the parasites of the Puerto Rican tree frog, (Eleutherodactylus coqui), in its native and introduced ranges. Biological Invasions, 10(8):1289-1298. http://www.springerlink.com/content/y112575l71305vvu/?p=a3710b0e88d34402b661b62689ad44b2&pi=8
Sin H; Beard KH; Pitt WC, 2008. An invasive frog, Eleutherodactylus coqui, increases new leaf production and leaf litter decomposition rates through nutrient cycling in Hawaii. Biological Invasions, 10(3):335-345. http://www.springerlink.com/content/j738636277573l84/fulltext.html
Tuttle NC; Beard KH; Al-Chokhachy R, 2008. Aerially applied citric acid reduces the density of an invasive frog in Hawaii, USA. Wildlife Research, 35(7):676-683. http://www.publish.csiro.au/nid/144/paper/WR07135.htm
ContributorsTop of page
Reviewed by: Dr. Fred Kraus, Department of Natural Sciences. Bishop Mueseum Honolulu, Hawaii. USA
Distribution MapsTop of page
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