Restricted diet in a vulnerable native turtle, Malaclemys terrapin (Schoepff), on the oceanic islands of Bermuda

Outerbridge, Mark E.; O'Riordan, Ruth M.; Quirke, Thomas; Davenport, John

Restricted diet in a vulnerable native turtle, Malaclemys terrapin (Schoepff), on the oceanic islands of Bermuda

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Published Version

Date

2017-01-26

Authors

Outerbridge, Mark E.

O'Riordan, Ruth M.

Quirke, Thomas

Davenport, John

Publisher

Amphibian & Reptile Conservation

Abstract

Diamondback Terrapins (Malaclemys terrapin) are native to Bermuda, presently inhabiting only four small brackish-water ponds. Their foraging ecology was investigated using direct observation, fecal analysis, and necropsy. They do not have as varied a diet as reported from their North American range. Small gastropods (<3 mm shell height) were found in 66.7% of fecal samples and made up 97.3% of animal material dry mass, thus dominating their diet. Scavenged fish and other vertebrates (19% of samples overall), plus terrestrial arthropods (14.3% of samples) were other common items. Polychaete worms and bivalves each occurred in less than 3% of fecal samples. Pond sediment was found in 74% of the samples, probably incidentally ingested while foraging (by oral dredging) for the gastropods. The distribution and abundance of arthropods and molluscs within the terrapins’ brackish-water environment were assessed in three different habitats; pond benthos, mangrove swamp, and grass-dominated marsh. These indicated that Bermuda’s terrapins do not fully exploit the food resources present. On Bermuda M. terrapin is basically a specialist microphagous molluscivore and mainly forages by deposit-feeding on gastropods living in soft sediments. This dietary restriction has made them particularly vulnerable to environmental contamination.

Keywords

Anchialine pond , Diamondback Terrapin , Fecal analysis , Feeding ecology , Aquatic gastropod

Citation

Outerbridge, M. E., O'Riordan, R., Quirke, T. and Davenport, J. (2017) 'Restricted diet in a vulnerable native turtle, Malaclemys terrapin (Schoepff), on the oceanic islands of Bermuda', Amphibian & Reptile Conservation, 11(1), pp. 25-35.