Cochran's treefrog  (Eleutherodactylus cochranae)

Cochran’s treefrog is classified as Least Concern (LC) on the IUCN Red List (1). 

Cochran’s treefrog (Eleutherodactylus cochranae) is a tiny amphibian known from the western Caribbean, growing to a maximum length of around two centimetres (2). This miniscule frog has a very angular, broad, flat head, a short body, and small pads on the long digits (3). The upperparts are grey, tan or grey-brown with a light grey pattern that resembles a pair of reversed parentheses (2) (4) (5). The limbs may be white, cream, yellow or grey, and the throat and the underparts of the thighs are speckled with fine brown spots (2) (4) (5). There is also a dark line between the large, conspicuous, forward-facing eyes (3) (4). 

The most common call of Cochran’s treefrog is a loud, repeated, single, rising whistle that is sometimes followed by one to three clicks (2).

Cochran’s treefrog is native to Puerto Rico, Isla Vieques, Isla Culebra, the British Virgin Islands and the U.S. Virgin Islands (1).

A largely arboreal species, Cochran’s treefrog lives in bromeliads and palms in dry wooded forests. It may also be found in disturbed and natural coastal grass-dominated wetlands and is fairly common around urban areas (1) (2) (4).

Primarily nocturnal, during the day Cochran’s treefrog resides in bromeliads or in crevices in trees (1). The male is known to have at least three, fairly simple calls: one for advertising to females, one for during courtship, and one that is emitted from a crevice when it is threatened by predators or other males (6). 

Cochran’s treefrog is thought to breed year round. After breeding, the eggs are laid between a fold in a bromeliad leaf. The leaf protects both the eggs and an adult of unknown sex, which attends the clutch. The eggs are thought to hatch after around two days. Cochran’s treefrog hatchlings develop directly, meaning that they skip the tadpole stage. The adult attends the juveniles for four or five days, when they then disperse (7).

There is little information available on the status of Cochran’s treefrog, but considering that it is a habitat generalist and fairly common around urban areas, its populations are probably stable (1) (4). However, in the British Virgin Islands almost a quarter of all amphibian species are categorised as endangered, suggesting the islands fauna is facing a wealth of threats. Habitat degradation and conversion to developments for tourism, human settlements and road construction are particularly severe problems, while predation from introduced mammals, such as rats and mongoose, also threatens many native species (8). It is not clear what impact these threats are having on the Cochran’s treefrog population there, but it is also thought to be declining with the spread of the predatory Cuban tree frog (Osteopilus septentrionalis) (1) (8). 

Although not the target of any known conservation measures, Cochran’s treefrog and its habitat are afforded protection in a number of reserves (1). On the British Virgin Islands a number of conservation recommendations have been made to protect the native fauna, including the creation of protected areas and minimising the impacts of development through the better enforcement of protective legislation (8). Increased monitoring efforts for amphibian populations may also be required given the potential for deadly diseases, such as the fungal disease chytridiomycosis, to break out on the islands, especially as disease has been associated with dramatic amphibian declines on nearby islands, such as on Puerto Rico (8) (9).

ARKive is supported by OTEP, a joint programme of funding from the UK FCO and DFID which provides support to address priority environmental issues in the Overseas Territories, and Defra

Find out more about conservation in the British Virgin Islands:

• British Virgin Islands Conservation Group:
  http://www.bvihcg.com/

For more information on amphibian conservation:

• IUCN Amphibian Specialist Group:
  http://www.amphibians.org/
• Amphibian Ark:
  http://www.amphibianark.org/