Background
The long-tailed duck is a sea duck and the most arctic-adapted of all ducks, requiring tundra habitat near lakes, ponds, coastlines, or islands for breeding.  In North America, it breeds from northern Ellesmere Island, Canada, to the south coast of Hudson Bay¹.  On the east coast, long-tailed ducks winter in coastal habitats from New England south to Chesapeake Bay, and less commonly, to the Carolinas¹.  Large numbers of long-tailed ducks winter off Nantucket and Chesapeake Bay; it is estimated that up to 30% of the North American breeding population may winter in the vicinity of Nantucket.  These ducks spend the night on Nantucket Sound and travel roughly 65 km offshore during the daytime to the Nantucket Shoals².  There are reported observations of up to several hundred thousand long-tailed ducks making this daily flight^2,3.

Climate Impacts
Climate change is expected to have an extreme impact on arctic and subarctic ecosystems^4,5.  The extent of tundra ecosystems is expected to decrease, and northward range expansions for tundra dependent species are not possible due to the lack of land further north⁴.  There has also been an observed increase in dominance of woody deciduous shrubs in many arctic regions over the past 50 years, altering tundra habitats^6,7.  Additionally, climate change may disrupt current predator-prey dynamics in the arctic, resulting in increased predation pressure on duck eggs.  Such a scenario has been suspected of decreasing breeding success of long-tailed ducks in some cases⁸.  It seems likely that these changes have the potential to negatively impact long-tailed duck populations.  However, there is limited information about the ecology and population dynamics of this species^9,10.

While activities in Massachusetts will have little direct impact on summer breeding habitat in the arctic, Massachusetts does host a disproportionate percentage of the wintering population of long-tailed ducks².  It is unclear how climate change will impact the current winter distribution of long-tailed ducks.  Large shifts in the winter distributions of other species of sea ducks have been observed, although causes of these shifts are unclear¹¹.  Climate change is expected to have an effect on the winter distributions of ducks in general, but for sea ducks, non-climatic factors, such as food availability, may also strongly determine distributions^8,12.  Additionally, changes in the timing of migration between summer and winter habitats are likely, but population impacts are unknown⁸.