Seaside Sparrow Genetics Research

By Carolyn Enloe

Seaside sparrows (Ammodramus maritimus) are extreme habitat specialists. They live in small isolated populations and with the exception of the Cape Sable subspecies in the everglades, they reside exclusively in saltmarsh. They require a special mosaic of saltmarsh habitat containing high elevation areas for nesting interspersed with open areas for foraging on insects and crustaceans and low muddy areas that exclude ground predators. Although the species ranges from Maine to Texas, the restricted breeding range of Florida subspecies coupled with their sedentary nature makes these populations particularly vulnerable.

A central problem in conservation biology is properly identifying “at risk” populations to effectively preserve biodiversity and maintain a species’ ability to cope with changing environmental conditions.

Taxonomy plays a crucial role in this process by identifying distinct units for conservation attention. Taxonomic uncertainties can have serious ramifications on conservation prioritization, listing status, and funding allocation that may be crucial to species survival. Currently, five recognized subspecies of seaside sparrow are resident in the marshes of Florida: Scott’s seaside sparrow (A.m. peninsulae), Wakulla seaside sparrow (A.m. juncicola), MacGillivray’s seaside sparrow (A. m. macgillivraii), Louisiana seaside sparrow (A. m. fisheri) and the critically endangered Cape Sable seaside sparrow (A. m. mirabilis).

Jeanelle Brisbane and Carolyn Enloe collecting blood from a Seaside Sparrow

 

Genetics studies in the late 1980’s revealed significant phylogenetic differences between gulf and Atlantic populations, but the Scott’s and Wakulla subspecies that reside on Florida’s gulf coast are currently delineated on distribution and weak morphological differences which have often been contradicted by molecular-based subspecies designations. In 2013, FWC recommended that subspecies relationships for seaside sparrows be re-examined using modern techniques.

In spring of 2016, FWC began collecting data for a genetics study to refine current taxonomic designations of seaside sparrows in Florida and to identify populations with low genetic diversity that may be at increased risk of extinction. After locating areas containing breeding sparrows, 14 sites were chosen for genetic sampling. Sampling began in May 2016 and ended in July to avoid collecting samples from migratory subspecies. We captured 170 birds using mistnets and collected 165 blood samples for DNA sequence analyses. Phenotypic data in the form of audio-recordings, morphometric measurements and photographs detailing plumagecharacteristics are also being taken of individuals at all sites to supplement genetics analysis and to create tools for managers to identify birds in the field. Sampling will resume in May 2017.