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Maryland Baseline Studies: Wintering Seabirds
Maryland Baseline Studies: Wintering Seabirds
Wintering seabirds were the most abundant avian group in the Mid-Atlantic region during this study. They include scoters, loons, gannets, alcids, and gulls, all of which migrate from their breeding grounds to spend the cooler months on the mid-Atlantic Outer Continental Shelf offshore of Maryland. The distribution and abundance of these species showed considerable variation over the course of the study.

Download Wildlife Studies Offshore of Maryland. This 8-page summary publication represents an overview of results from the final technical report for the Maryland-focused study, and features survey results and case studies on marine mammals, sea turtles, and wintering seabirds. The Executive Summary for the technical report is also available here.

Additional results and case studies can be found in the 32-page synthesis report for the mid-Atlantic regional study, Mid-Atlantic Wildlife Studies: Distribution and Abundance of Wildlife along the Eastern Seaboard, 2012-2014.

 

Take Home Messages

  • Because seabirds have varied life histories, distributions, and habitat requirements, future development will likely influence each species uniquely.
  • Some are more likely to be affected by collisions with turbines; for others, displacement from wind facility areas may result in habitat loss.
  • Species distributed in offshore areas that overlap with WEAs may have a greater chance of displacement or collision than those with nearshore ranges.
 

Distribution and Abundance

We paired boat survey data with remotely sensed environmental data (from satellites) from the same time periods to predict the abundance and distributions of wintering seabirds in areas that were not surveyed. We used this information to make inferences about the habitat used by different species.

In this study, wintering seabirds showed considerable variation in distribution and abundance. Overall abundance was higher in the second winter of the study than the first. Scoters were the most abundant seabirds; large flocks were observed within about 30 km of shore, particularly at the mouth of Chesapeake Bay and along the northern shore of Maryland. Loons were more commonly observed individually or in small groups, and Red-throated Loons were seen closer to shore than Common Loons. Northern Gannets and wintering gulls were widely distributed across the study area, though gannets were abundant within 30 km of shore, while Bonaparte’s Gulls were farther offshore. Alcids were also most consistently observed farther from shore.

During both years of the study, scoters used nearshore waters with high primary productivity. The rest of the wintering seabird community showed more variable relationships with environmental covariates between years. The high level of interannual variability in seabird distributions suggests that seabird prey may have been responding to different environmental conditions between the two winters.

The three maps above show predicted abundance of scoters and other wintering seabirds for a given date during winters of 2012-2013 and 2013-2014. Model outputs combine observation data from boat-based surveys with environmental data to predict wintering seabird abundance across the regional study area. Scoter patterns were similar in both winters surveyed, while other seabirds showed notable interannual variation in distributions.
The three maps above show predicted abundance of scoters and other wintering seabirds for a given date during winters of 2012-2013 and 2013-2014. Model outputs combine observation data from boat-based surveys with environmental data to predict wintering seabird abundance across the regional study area. Scoter patterns were similar in both winters surveyed, while other seabirds showed notable interannual variation in distributions.
 

For More Information

For more information, see Chapters 9 and 11 in the technical report.
 

References

  • Fox AD, Desholm M, Kahlert J, Christensen TK, Petersen IK (2006) Information needs to support environmental impact assessment of the effects of European marine offshore wind farms on birds. Ibis 148: 129–144. doi: 10.1111/j.1474-919X.2006.00510.x
 
Photo Credits: Header image © Daniel Poleschook
Biodiversity Research Institute