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Merritt Island National Wildlife Refuge
Research Papers and Abstracts

Dwarf Siren (Pseudobranchus striatus)
Trisha Crabill holding the northern dwarf siren (Pseudobranchus striatus) specimen that was captured on the Merritt Island NWR. CLICK for an enlargement.

Researcher Discovers Dwarf Siren (Pseudobranchus striatus) on Merritt Island National Wildlife Refuge

Submitted by MARC EPSTEIN
U.S. Department of the Interior Fish and Wildlife Service
Merritt Island National Wildlife Refuge
P. O. Box 6504, Titusville, Florida 32782

On December 9, 2005, Trisha Crabill, a graduate student conducting research on her Master of Science degree in biology from Towson University, discovered a northern dwarf siren (Pseudobranchus striatus) on the Merritt Island NWR. The significance of this find is that it has never before been reported this far south in its range and the discovery extends the known distribution of the species south into Brevard County, Florida.

Trisha Crabill was accompanied by Marc Epstein, Senior Refuge Biologist, at the time of capture. The small aquatic salamander was found in a trap set to target its larger relatives, the greater and lesser sirens (Siren lacertina and Siren intermedia). Both of the larger siren species are being captured as part of a study examining the benefit of roadside ditches as habitat for wildlife. To assess the suitability of the ditches, Trisha is comparing populations of sirens in the roadside ditches to those in natural wetlands and will use measures such as growth rates, reproduction, and survivorship. Trisha is working under the guidance of Dr. Richard Seigel, also from Towson University, who has been researching the amphibians and reptiles of the Kennedy Space Center for over twenty-five years.

Sirens are large aquatic salamanders that live solely in the water. Unlike other salamanders, sirens have no hind legs and retain their gills into adulthood. The most unique feature about sirens is their ability to withstand periods of drought by burrowing in the mud to aestivate. A mucous skin secretion creates a cocoon around the animal allowing it to stay burrowed in the mud for several months without dehydrating. Despite the abundance and commonness of sirens, most people are unfamiliar with the salamanders because of their secretive nature and the fact that they rarely leave the water.

Trisha Crabill with Siren live-trap. Trisha Crabill with a captured greater Siren.
Trisha Crabill, graduate student studying Sirens on the Merritt Island NWR checking one of her many Siren live-traps in a wetland drainage system on the refuge. Trisha is smiling because she has been lucky enough to capture another greater siren in this trap.
CLICK for an enlargement.
Trisha Crabill with a captured greater Siren. Trisha is using radio-telemetry to determine the distribution and movements of Sirens on the Merritt Island NWR.
CLICK for an enlargement.
Dwarf sirens, the smallest genus of sirens, are found primarily in the south Atlantic coastal states and are comprised of two different species, the northern dwarf siren (Pseudobranchus striatus) and the southern dwarf siren (Pseudobranchus axanthus). The southern dwarf siren occurs primarily in Florida and the northern species is found from coastal South Carolina to north Florida. Both species are typically found in wetlands containing dense mats of water hyacinths in which they forage for invertebrates and insects. The northern dwarf siren has been documented in Volusia County just to the north, but this is the first record for Brevard County, which extends the known southern range of the species. It is interesting that it was found on Merritt Island, a coastal barrier island system that is basically isolated from adjacent, mainland freshwater wetlands.

Aside from extending the range, the discovery of the dwarf siren on the refuge is exciting because rarely are new native species recorded. All new species discovered within the past ten years have included introduced, exotic species such as brown anoles, which are considered to have negative impacts on the native species.

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