Osteopilus septentrionalis, commonly known as the Cuban tree frog, is an amphibian native to the Caribbean region of the Western Hemisphere. It is the largest tree frog of North America. Their wide diet and ability to thrive amongst humans has made it a highly invasive species with established colonies in Northern Florida, the Hawaiian island of Oahu, and thorough the Caribbean Islands.^[1] They range in size from 3 to 5.5 inches (76 to 140 mm) and vary in color from olive-brown, bronze, gray, or grayish-white. A nocturnal tree dwelling frog, they are known to eat almost anything that will fit in their mouth and to mate year-round. Their arrival in a new community is believed to be detrimental to local species and it has been suggested that these frogs be destroyed on sight upon their arrival in new habitats. Cuban tree frogs are commonly available as pets; however, because the animal secretes a toxic mucus from their skin that can cause a burning sensation in the eyes it is not an ideal pet. It is also believed that further distribution of the species has been expanded by the release of these pets.

Description

Cuban tree frogs can vary greatly in color, sometimes appearing white when inactive or cold.

The Cuban tree frogs range in size from 3 to 5.5 inches (76 to 140 mm) in length. It is the largest tree frog in North America and has a rough warty skin.^[2] Their toepads are much larger than those of other tree frogs and they will often have an orange-tint to their eyes.^[3] Varying in color from, olive-brown, bronze, gray,^[3] or grayish-white.^[4]

Cuban tree frogs can change colors depending on their temperature and environment. Many individuals have darker splotches on the back, and some splotchy banding on the legs. In many individuals, the hidden surfaces of the legs are bright yellow. When the frog leaps to avoid a predator, these bright yellow patches are visible, and may help to confuse the predator. Also, the skin on their heads is fused to the skull—if the head of an adult frog is rubbed (between the eyes), the skin does not move. This is a special adaptation that prevents water loss, since there are fewer blood vessels in the "co-ossified" (fused) area. When handled, Cuban tree frogs secrete a toxic mucus from their skin. In humans, this can cause an allergic reaction or burning sensation to the eyes and nose, and even trigger asthma.

Behavior

Excellent climbers the Cuban tree frogs will typically sleep above ground during the day.^[1] During the night Cuban tree frogs forage for insects in sources of artificial light.^[1] Indiscriminate predators they will eat anything they can overpower and fits into their mouth, including: snails, spiders, insects, other frogs (even other Cuban tree frogs), snakes, lizards,^[1] small crustaceans,^[5] and hatchling birds in their nest.^[4] Their foraging will occasionally take them up utility poles where they can cause short-circuits of utility switches, causing costly power outages.^[6]

Life cycle

Cuban tree frogs are sexually dimorphic–females are larger than males. Breeding males can be identified by their development of black nuptial pads on their thumbs,^[5] which help the male to hold onto the female during mating.

Cuban tree frogs breed year round, but most commonly occurs in the wet season, between May and October. Optimal conditions are considered to be 81.5 °F (27.5 °C) with high humidity (97.8%) and rain.^[7] They lay a partial clutch of eggs in varying size ranging from 100-1,000. The full clutch is average a total of 3,961 and varies based on female body size. Eggs can hatch in under 30 hours and can fully develop in 1 month.^[7] Much like their adult counter parts newly hatched tadpoles can come in a variety of colors and patterns.^[7] They have a wide caudal fin and two rows of labial teeth on the top of the mouth and four rows on the bottom.^[5] Tadpoles survive off of algae and will occasionally turn to cannibalism eating other tadpoles^[7] and on rare occasions recently metamorphism juveniles.^[8] After transformation are between 0.55 and 0.67 inch (14 and 17 mm), while the tail is entirely absorbed.^[5]

Distribution

This green-colored Cuban Tree Frog was photographed in Cocoa, Florida.

The Cuban tree frog is native to Cuba, the Bahamas, and the Cayman Islands. This large frog has been introduced in Puerto Rico, the U.S. Virgin Islands, the British Virgin Islands, many islands of the Lesser Antilles, and Hawaii. There is debate over if the species was native to the Key West region of Florida,^[7] or if it was introduced to the area. First discovered in the 1930s,^[9] it is theorized that they might arrived on ships in the 1800s^[8] or could have made it to the area by natural means.^[9] They can survive in brackish water and this ability may have helped the species to spread to various islands.^[5] The Cuban tree frogs progressed colonization into the mainland of Florida is believed to be by use of Florida State Road A1A construction during the 1940s.^[10] The species is now established in southern Florida and parts of the panhandle region and can be found as far north as South Carolina.^[1]

The Cuban tree frog is known to hitchhike on shipments of potted plants,^[11] vegetation, packaging,^[10] boats, and other motorized vehicles.^[1] Once in a new location the frogs become an invasive species. They have several good colonizing traits, such as: high fecundity, short generation time, a diverse diet, good competitive ability, and the ability to co-exist with humans.^[10] In addition they also secrete a toxic mucus from their skin which helps to limit the number of natural predators.^[4]

Cuban tree frogs are known to inhabit a variety of communities, including estuarys, low-density suburban development, small towns, agricultural areas, particularly ones with exotic plants, and lowland forests and swamps.^[12] Within their habitat they can be found in damp, shady areas, particularly around shrubs and trees,^[2] by cisterns, rain barrels,^[5] and buildings.

Conservation

The large frog directly impacts native ecosystems by eating native frogs, lizards, and snakes and poses a threat to the biodiversity of the areas into which it spreads by causing native tree frog populations to decline. These effects are most noticeable in urban and suburban areas, where native tree frogs such as the American green tree frog (Hyla cinerea) and the Squirrel treefrog (Hyla squirella) are rapidly disappearing. It has spread throughout peninsular Florida, and is also commonly found in isolated populations as far north as southern Georgia.^[13] It hitchhikes on vehicles or ornamental plants, spreading to new areas, and has been transported as far north as Canada. Because of its effects on the biodiversity some experts have recommended killing the animal when it is found in a new habitat.^[11]

In captivity

Cuban tree frogs are commonly available in the pet trade within the United States.^[4] They are inexpensive, and when cared for properly tend to live 5–10 years. They feed readily on commercially available crickets, however while in captivity they may turn to cannibalism.^[3] The skin of Cuban tree frogs secretes a toxic mucus that can burn the eyes and trigger an allergic (or asthmatic) reaction; as a result, this species is not an ideal pet species, especially for children. The Cuban tree frog's colonization of the Hawaiian island of Oahu is believed to be a result of accidental or deliberate release of pets. Therefore the species is now banned from sale in Hawaii. Conviction of importation of a Cuban tree frog carries a maximum fine of $25,000 and a year in jail.^[4]

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