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Waterfowl: Movement Studies
Waterfowl: Movement Studies

Tracking Common Eider Brood Survival in Casco Bay, Maine

The current population status for the Common Eider (Somateria mollissima) within the Atlantic Flyway suggests a population in decline and cause for concern for wildlife managers and for eider conservation. The American common eider is a focal species for the U.S. Fish and Wildlife Service and has been identified as a high priority species by the Sea Duck Joint Venture, to evaluate duckling survival and evaluate potential management actions directed at increasing or sustaining current eider populations. Maine’s coastline supports an abundance of islands which are critical breeding areas for a significant proportion of the population of American common eiders. In May 2016, a pilot field study was initiated in Casco Bay, Maine, to evaluate field methodologies designed to document eider duckling survival. Our long-term goal is to use our field findings to guide management actions to conserve the American common eider.

BRI Lead Investigator: Lucas Savoy

Project Components

Project Components

Our goal was to uniquely mark a proportion of female common eiders at a nesting colony in Maine, in order to track each individual hen’s broods of young until age of fledging and assess duckling survival rates. To uniquely mark hens, we captured common eider hens, prior to their nesting period, and attached colored plastic nasal discs to their bills, as well as a VHF radio transmitter. These methodologies were well described and successfully utilized for common eiders and other sea ducks. The nasal discs are temporary, and are designed to remain on the hens throughout the brood rearing summer months and fall off the birds prior to the post-breeding period in the fall. We conducted preliminary nasal disc attachment technique experiments with captive common eiders, in collaboration with the Livingston Ripley Waterfowl Conservancy. Throughout the nesting and brood rearing periods (May-July), we will conduct multiple boat-based surveys each week, to document each hen’s location and breeding status, and track the fate of each brood to assess duckling survival. If marked hens move outside of the boat survey area, we will attempt to locate them with an airplane, equipped with radio telemetry.

Project Updates

Project Updates

In early May, our field team visited a common eider nesting colony in Casco Bay, Maine. The timing of our visit was designed to safely capture hen eiders, prior to the onset of egg-laying and nesting activities. We utilized a floating mist net technique to capture hen eiders paired with mates near their nesting island. Healthy hen eiders were weighed, measured, banded, and uniquely marked with plastic nasal discs and an external radio transmitter; we marked a total of 50 hens. We have begun conducting weekly boat-based surveys, utilizing radio telemetry tracking equipment and nasal disc re-observations in order to locate each individual hen and determine the presence or absence of ducklings.
Project Team

Project Team

This field study is comprised of numerous project investigators from multiple wildlife agencies and organizations.

Chris Dwyer, U.S. Fish and Wildlife Service Region 5, Hadley, Massachusetts
Lucas Savoy, Biodiversity Research Institute, Portland, Maine
Brad Allen, Maine Department of Inland Fisheries and Wildlife, Bangor, Maine
Dan McAuley, USGS Patuxent Wildlife Research Center, Orono, Maine.

Thank you to the many individuals involved with field efforts.

Michelle Kneeland, Bill Hanson, Tim Welch, Alex Dalton, Carrie Gray, Rick Gray, Robby Lambert, Lauren Gilpatrick (BRI); Kelsey Sullivan (MDIFW); Bob Houston (USFWS). Thank you to Nick Tiberio and the Livingston Ripley Waterfowl Conservancy for facilitating preliminary eider tagging techniques.
 

SEE US IN ACTION!

View our photoalbum of this project to see images of Common Eider fieldwork in action.

Tracking Common Eider Brood Survival
 
Photo Credits: A female Common Eider equipped with a satellite transmitter © Chris Dwyer; Releasing a female Common Eider © Chris Dwyer; A female Common Eider equipped with a satellite transmitter © Chris Dwyer; Attaching a satellite transmitter to a female Common Eider © Chris Dwyer
Biodiversity Research Institute