Development of genetic markers for evaluating fine-scale population structure of Western Grebes (Aechmophorus occidentalis) and Clark's Grebes (A. clarkia)

Derek Girman
Sonoma State University
$34,786

Coastally wintering populations of Western Grebes (Aechmophorus occidentalis) in Washington and British Columbia are in evident decline, with a status review currently being undertaken in Washington state. Much concern has been raised about this species lately, and a Western Grebe working group was recently formed for precisely this reason. The majority of Western Grebes winter in inland marine waters from Baja California to British Columbia and breed inland at colonies on suitable lakes throughout much of western North America. Threats to their population occur on both breeding and wintering areas, and include high vulnerability to oil spills and heavy disturbance on many breeding colonies. Increasing our understanding of metapopulation dynamics and source populations in this species is critical. Determining the linkages between wintering and breeding birds would be an important step in identifying the factors limiting their populations, and would result in appropriate management actions. In regions where population declines are observed, increased understanding of these linkages might aid in determining the causes of the declines and potentially lead to directed management actions that could curb or reverse these trends.

Directly evaluating movements with previous approaches has so far proven challenging for this species. We will use genetic markers called microsatellites to differentiate breeding populations and determine the genetic associations among breeding and wintering sites. To accomplish this, our efforts in this project will include the development of genetic markers for the species. Many of our samples, especially for wintering birds, will be collected through collaboration with other researchers, beached bird surveyors, museums, and rehabilitation centers, many of which have already been identified. The application of these genetic markers has the potential to produce information that is greatly needed to understand factors repsonsible for declines in Western and Clark’s Grebes.