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Authors:Gayle, Stephanie
Contributors:Mautz, William (advisor)
Tropical Conservation Biology & Environmental Science (department)
Keywords:Environmental science
Eleutherodactylus coqui
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Date Issued:May 2020
Publisher:University of Hawaii at Hilo
Abstract:The invasive coqui frog (Eleutherodactylus coqui) has rapidly colonized four main Hawaiian islands, and its populations have spread over large areas producing a number of negative social, ecological, and economic impacts. On Hawaii Island, coqui frogs occur over major tracts of coastal forests and the lower boundaries of montane wet forests at higher elevations, and population sizes and densities are highest in the state. In their native Puerto Rico, coqui frogs are found from sea level to the top of the island (1,065 m) and it is currently an open question how high coqui frog populations will eventually range on Hawaii Island. Cold temperature limitation is a strong hypothesis for the current altitudinal distribution of this species on Hawaii Island. In this study, the thermal limitations on coqui frog calling behavior were determined in order to infer if cooler high altitude temperatures serve as a limiting condition for the continued expansion of coqui frog populations. Coqui frogs were found to stop calling around 14°C at high elevation and around 19°C at low elevations while normal levels of chorusing occurred around 17°C and 21°C at high and low elevations, respectively. Differences in mean air temperature observed between elevations were very similar for different degrees of calling activity, suggesting that higher elevation populations have acclimatized or adapted to be active under cooler conditions. In addition to low temperature, low moisture was also found to be associated with low levels of coqui frog calling activity. Strong negative relationships between temperature and temporal calling parameters (inter-note interval and total call length), and strong positive relationships between temperature and call note (‘co’ and ‘qui’) center frequencies were observed for high elevation coqui frog populations. These relationships between temperature and coqui frog calling support some observations reported over smaller temperature ranges in previous studies. The coqui frogs’ thermal tolerances imply that they can occupy habitats throughout all the Hawaiian islands except for the alpine and summit areas and drier grassland and shrub environments. While the effects of coqui frogs on lowland ecosystems replete with non-native species have been unexpectedly modest, the frogs could have greater impact at higher elevations where native flora and fauna assemblages dominate. Such sensitive habitats should be monitored for possible unappreciated effects of coqui frog populations.
Pages/Duration:54 pages
Rights:All UHH dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Tropical Conservation Biology and Environmental Science
TCBES Theses

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