Chytrid Fungus

In collaboration with the Hawaii State Department of Agriculture, the T-STAR Hawai`i Coqui Frog Invasive Species Project has consulted with researchers on a fungus Batrachochytrium dendrobatidis that causes a lethal amphibian disease called chytridiomycosis. Because there are no native amphibians here in Hawaii, chytridiomycosis was considered an option for controlling the coqui frog. There is a strong possibility that the fungus is already present in Hawai’i, but if left to run its natural course, the disease may take years to begin to control the coqui frog population. Tests conducted at the University of Colorado on adult coqui frogs found that, while the frogs may carry the chytrid fungus, they are not susceptible to its pathogenic effects and do not get sick or die from it.  In addition, chytridiomycosis is an emergent wildlife disease; there is not much known about its host specificity.  It was, therefore, concluded that B. dendrobatidis would not be effective or suitable as a control agent for coqui frogs in Hawaii.

For more information regarding this topic, please visit the Diagnosis of Chytridiomycosis in amphibians by historical examination information website (Berger, L., R. Speare, and A. Kent, http://www.jcu.edu.au/school/phtm/PHTM/frogs/histo/chhisto.htm, 20 November 1999), and Chytridiomycosis in Amphibians in Australia research website ( Speare, R. and L. Berger http://www.jcu.edu.au/school/phtm/PHTM/frogs/chyspec.htm. 26 January 2005).

Internal Parasites

Several internal parasites were found during examination of coqui frogs collected in Puerto Rico.  Further research will investigate the effects of some of these parasites on the health of coqui frogs and to evaluate their effects on non-target organisms.

Chickens

Since there have been numerous reports of chickens consuming coqui frogs, trials were conducted with wild chickens and have yielded mixed results.  Chickens are active during the day while the frogs are taking refuge from the sun. Chickens will eat coqui frogs they encounter when scratching if the frog is moving, but frogs are not their primary food source.  These trials have only been conducted in cages where frogs do not have a clear means of escape.  In large, open areas frogs will likely hop away before chickens have a chance to catch them.  Similarly, feral cats, rats, and mongoose may opportunistically eat coqui frogs, but frogs are not their primary food source and it is highly unlikely they reduce frog population sizes.  

Given the potential for an increased number of feral chickens, cats, rats, and mongoose, and the ecological problems and noise disturbances associated with them we do not recommend the use of these animals as a coqui frog control measure.