Dietary overlap between the invasive coquí frog (Eleutherodactylus coqui) and the Hawaiian hoary bat (Lasiurus cinereus semotus) on the Island of Hawai’i

Abstract

The invasive coqui frog is a likely insectivorous competitor to the native Hawaiian hoary bat. The frog is a sit-and-wait predator native to Puerto Rico, but it has the capacity for producing dense populations in its invasive range and the potential to reduce arthropod populations, including aerial arthropods in the orders Coleoptera, Lepidoptera and Isoptera, which are primary food sources of the Hawaiian hoary bat. Dietary analysis of the coqui frog showed that aerial insects made up 33.8 % of the diet. The dietary similarity of the bat and frog was relatively low (Pianka index = 0.25), however, coqui frogs consumed a wide range of juvenile flying insects. Population densities of coqui frogs at two low elevation sites were projected to range from 750 to 14,000 individuals/hectare, and could consume an estimated 1500–19,000 aerial insects/hectare/night, or nearly 90.6 % of all available aerial insects/hectare. Although direct competition between coqui frogs and Hawaiian hoary bats was not confirmed, the coqui frogs could reduce available prey for bats in newly invaded upland sites where bats appear to be more selective of prey species among available aerial insects.