Date of Award:

5-2016

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Committee Chair(s)

Karen H. Beard

Committee

Karen H. Beard

Committee

David N. Koons

Committee

Aaron B. Shiels

Abstract

The Puerto Rican coqui frog was introduced the Hawaiian Islands in the late 1980s. Because of the frog's loud call and high abundance, the State of Hawaii has spent millions of dollars on its eradication. Conservationists are also concerned that the frog could negatively impact Hawaii's endemic birds, which are already threatened by a host of other invasive species, either by competing with them for insects or by increasing bird predators. The purpose of this research was to investigate the impacts of coquis on Hawaiian birds. First, we examined overlap in prey resources between coquis and birds, and second, we investigated whether coquis change bird abundance across Hawaii Island.

We used naturally occurring stable isotopes to quantify the position of coquis and birds in the food chain. We found that coquis and insectivorous birds do occupy a similar position in the food web. However, using more detailed analyses of their diets, we found that the birds and coquis did not share many prey resources. Coquis mostly feed on insects on the forest floor, while insectivorous birds feed on insects in the forest canopy. This suggests that coquis and birds do not strongly compete.

We measured bird populations in coqui and non-coqui areas across 15 sites on the island of Hawaii. We found that bird abundances were never lower in coqui areas, suggesting that coquis do not negatively impact birds in Hawaii. We found that coquis co-exist with four native species. Non-native predatory birds increased in coqui areas, suggesting that the primary way coquis affect birds is by serving as a food resource.

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Included in

Life Sciences Commons

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