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Case Study: Scoters
Case Study: Scoters

Context

Scoters are medium-sized sea ducks that breed in the Arctic. Three scoter species live in North America and winter in the mid-Atlantic (Black, Surf, and White-winged Scoters). This taxon was a focus of this study because they are highly abundant in the study area, and European studies found that scoters may be displaced from areas around offshore wind facilities for some period of years following construction.

Download Mid-Atlantic Wildlife Studies: Distribution and Abundance of Wildlife along the Eastern Seaboard 2012-2014. This 32-page summary publication explores aspects of the mid-Atlantic ecosystem; describes our survey and analytical approaches; and presents a range of results, featuring several case studies on specific species or phenomena.

The Executive Summary for the technical report is also available here.

 

Take Home Messages

  • Telemetry and survey data for scoters indicated strong nearshore distribution patterns, which held true across species and were largely driven by water depth.
  • In the mid-Atlantic, construction and operation of offshore wind energy facilities (and associated vessel traffic) are most likely to cause localized displacement of scoters from high-quality feeding areas if these activities occur within about 20 km from shore.
 

Background

Scoters breed near lakes or slow-moving rivers in the boreal forest and taiga from Labrador to Alaska. They form breeding pairs in the wintering areas—mostly shallow bays and estuaries in temperate regions along the east and west coasts of North America. Scoters forage by diving and swimming underwater. On breeding grounds, they primarily consume aquatic invertebrates and some plant material. In winter, scoters predominantly forage on mollusks in shallow nearshore waters with sandy substrates.

The Surf Scoter and White-winged Scoter both have a Conservation Status of Least Concern from the International Union for the Conservation of Nature due to large populations and broad ranges, despite trends for both species that indicate declines. The Black Scoter is listed as Near Threatened due to suspected recent population declines. Threats to these species include habitat degradation, oil spills, human disturbance and commercial shellfish harvests.

Related species have demonstrated avoidance at several offshore wind facilities in Europe, causing effective habitat loss of feeding or roosting areas. There is some evidence for habituation or re-initiation of habitat use several years after construction. Scoters are also known to be disturbed by vessel activity, with displacement effects varying by species.

 

Distribution and Abundance

Winter utilization distribution for satellite-tagged Surf Scoters (n=101; data are preliminary). Additional capture locations in Labrador, Québec, and New Brunswick are not shown on this map.
Winter utilization distribution for satellite-tagged Surf Scoters (n=101; data are preliminary). Additional capture locations in Labrador, Québec, and New Brunswick are not shown on this map.
 
Predicted abundance of scoters (including White-winged, Black, and Surf Scoters) for a given day during winter 2013-2014. Model outputs combine observation data from boat-based surveys with environmental covariate data to predict scoter abundance across the study area. The highest abundance of scoters was predicted to occur close to shore and in regions with high primary productivity.
Predicted abundance of scoters (including White-winged, Black, and Surf Scoters) for a given day during winter 2013-2014. Model outputs combine observation data from boat-based surveys with environmental covariate data to predict scoter abundance across the study area. The highest abundance of scoters was predicted to occur close to shore and in regions with high primary productivity.
 

Behavior and Habitat Use

Scoters were the most abundant avian genus observed over the course of the study. Individual satellite tagged Surf Scoters generally arrived between mid-October and mid-December, spending an average of 133 days in the region. In general, they left the study area between early January and mid-May, following the coast north to briefly stage in the St. Lawrence Estuary before continuing north to breeding and molting areas in northern Canada. The route was reversed during fall migration.

Large aggregations were most consistently observed at the mouth of Chesapeake Bay and just south of the mouth of Delaware Bay within about 30 km of shore. Survey and telemetry data showed scoters used habitat characterized by shallow nearshore waters with high primary productivity.

 

Temporal Variation

Surf Scoters were most commonly observed on the boat-based and digital aerial surveys in winter, and none were observed from May to August.

On average, Surf Scoters tracked with satellite telemetry arrived in the study area in November, and left in April. A time variant kernel density model of satellite telemetry data was developed to improve our understanding of the species’ use of the landscape through time. The movement video generated from this model is shown here.

 

For More Information

For more information, see Chapters 12, 17, 20, and 23 in the technical report.

These telemetry data were gathered as part of a longer-term study of Surf Scoters, initiated by the Sea Duck Joint Venture and funded by multiple agencies and organizations.

Funders and collaborators for this effort are listed on the study methods page.

 

References

  • Anderson EM, Dickson RD, Lok EK, Palm EC, Savard J-PL, Bordage D, Reed A (2015) Surf Scoter (Melanitta perspicillata), in: Poole A (ed) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca, NY. doi:10.2173/bna.363
  • BirdLife International (2015) IUCN Red List of Threatened Species. Version 2015.2. www.iucnredlist.org Accessed 09 July 2015
  • Kaufman K (1996) Lives of North American Birds. Houghton Mifflin Co., Boston, MA. 675 pp. Larsen JK, Guillemette M (2007). Effects of wind turbines on flight behaviour of wintering common eiders: implications for habitat use and collision risk. Journal of Applied Ecology 44:516–522. doi:10.1111/j.1365-2664.2007.1303.x
  • Petersen I, Fox A (2007) Changes in bird habitat utilization around Horns Rev 1 offshore wind farm, with particular emphasis on Common Scoter. Report commissioned by Vattenfall A/S. National Environmental Research Institute. 36 pp
  • Schwemmer P, Mendel B, Sonntag N, Dierschke V, Garthe S (2014) Effects of ship traffic on seabirds in offshore waters: implications for marine conservation and spatial planning. Ecological Applications 21:1851–1860
  • Sea Duck Joint Venture (2015) Atlantic and Great Lakes Sea Duck Migration Study [online]
  • Stott RS, Olson DP (1973) Food-habitat relationship of sea ducks on the New Hampshire coastline. Ecology 54:996–1007
 
Photo Credits: Header image © BRI-Jonathan Fiely; Maps © BRI
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