Diet of the Introduced Greenhouse Frog in Hawaii

To determine the potential impacts of the Cuban terrestrial Greenhouse Frog, Eleutherodactylus planirostris, on native invertebrates in Hawaii, we conducted a stomach content analysis of 427 frogs from ten study sites on the island of Hawaii. At each site, we also collected invertebrates with two sampling methods, leaf litter collection and sticky traps, to determine if diets were representative of the available resources. Dominant prey items consisted of Hymenoptera: Formicidae (32.4% of total diets), Acari (19.2%), and Collembola (17.4%). Non-native invertebrate categories comprised 43.2% of their diet (Amphipoda, Isopoda, and Hymenoptera: Formicidae). Invertebrate orders that contain native species in Hawaii found most often in the stomachs included Acari (mites; 19.2%), Araneae (spiders; 3.1%), Collembola (springtails; 17.4%), and Psocoptera (booklice; 2.3%), although it is unknown whether native species of these groups were present in the stomach samples. Eleutherodactylus planirostris predominantly consumed leaf litter invertebrates and selected proportionately more Formicidae than was available in the environment. A total population density of 12,500 frogs ha⁻¹ was estimated at one study site. With this density estimate and number of prey consumed, E. planirostris may consume 129,000 invertebrates ha⁻¹ night⁻¹ at some sites. This research highlights the need to understand the direct and indirect effects of predation by E. planirostris on invertebrates in Hawaii.