Habitat use and movements of common eiders wintering in southern New England

Abstract

Little is known about the habitat use patterns and movement ecology of American common eiders (Somateria mollissima dresseri) despite potential negative impacts on habitat and eider populations from anthropogenic sources (e.g., oil spills, hunting, offshore wind energy facilities). We used satellite telemetry to quantify migratory phenology, home range size, winter site fidelity, and resource selection of adult female eiders (n ¼ 24) from December 2011 to July 2013 that were captured during winter in southern New England, USA. Eiders spent 39% of their annual cycle in southern New England. In spring, eiders took an average of 16 days (range ¼ 2-47) in 2012 and 20 days (range ¼ 1-61) in 2013 to migrate from wintering grounds to summer areas, whereas the duration of fall migration averaged 47 days (range ¼ 7-115). Eiders exhibited high site fidelity to wintering areas, with 83% of birds with active transmitters (n ¼ 23) returning to the study area the following winter (2012)(2013). Mean individual core use home ranges on wintering grounds averaged 38.5 km 2 and 95% utilization distributions were 199.3 km 2 . Based on habitat selection models, eiders preferred shallow, nearshore waters that had relatively fine sediments and a high probability of hard bottom. We estimated that only 3% of our 6,212-km 2 study area had a high relative probability of use by eiders. Future development (e.g., offshore wind energy developments) should avoid shallow, nearshore waters with hard bottoms preferred by eiders to minimize potential impacts. Ó 2017 The Wildlife Society.KEY WORDS common eider, migration phenology, satellite telemetry, site fidelity, Somateria mollissima dresseri, southern New England, winter habitat use.

Spatially explicit network analysis reveals multi‐species annual cycle movement patterns of sea ducks

“…Since 2002, the project and other associated tracking efforts have collected annual cycle movement data from 672 individual birds representing five species, including Common Eider (Somateria mollissima), Black Scoter (Melanitta americana), Surf Scoter (M. perspicillata), White-winged Scoter (M. deglandi), and Long-tailed Duck (Clangula hyemalis). To date, analyses of these data have focused on species-specific movement patterns and habitat use (Loring et al 2014, Beuth et al 2017, Spiegel et al 2017, Meattey et al 2018). However, the complete dataset provides a unique opportunity to examine and compare movement patterns across several sympatric species tracked simultaneously.…”

Sample size considerations for satellite telemetry and animal distributions

“…This large investment requires careful consideration of the benefits of the resulting information, and careful pre‐study planning to ensure success. To date, information from satellite telemetry has provided critical information on key sea duck habitats, migration timing and routes, and site fidelity from a relatively small number of birds (Petersen et al , Loring et al , Sea Duck Joint Venture , Beuth et al ). Our analyses suggest, however, that characterizing habitat use and distribution at the population level using strictly satellite telemetry data will require substantial additional investment.…”

Body composition dynamics of common eider during winter: An application of the deuterium dilution method

“…Body mass and fat mass of male and female eiders increased during late winter in southern New England, suggesting that birds were able to secure adequate resources to improve their body condition over the course of the winter period. This interpretation assumes that this population of common eider resides in southern New England throughout the winter as shown with eiders implanted with satellite transmitters (Beuth et al ). In contrast, body mass of male northern common eiders in Scotland did not change over winter, although body mass of females significantly increased in late winter (Milne ).…”

“…To estimate seasonal variation in body composition of eiders, we used floating mist nets and decoys (Brodeur et al ) to capture approximately 30 adult eiders during each of 3 winter periods (early winter, just after birds arrived to southern New England, 13 Nov–14 Dec 2011, n = 35; midwinter, 6–16 Feb 2012, n = 29; late winter, 1 month prior to spring migration, 15–19 Mar 2012, n = 26; Beuth et al [] reported the migration phenology of this population of common eider). We determined age and sex of captured eiders using wing plumage characteristics (Carney ).…”

“…We immediately released after banding the other 37 adults that were captured, as well as all 75 juvenile eiders captured during fieldwork. We included more adult eiders during early winter because this project was part of a larger satellite telemetry study for which we estimated body composition of eiders when transmitters were deployed (Beuth et al ).…”