We focus on the phenomenon of migration because it is a critical stage in the life cycle of many animals. The consequences of interactions between migratory wildlife and offshore wind facilities are unclear. Some species may have increased collision risk. Others may have increased energetic expenditures from avoidance during migratory movements, although these effects will depend on the scale and number of offshore wind facilities along a migration route.
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.
Our research suggests that a wide variety of animals migrate through areas that have been proposed for offshore wind energy development in the mid-Atlantic region. Additional research on migrant populations may be warranted for sites proposed for development or other offshore activities.
Migration is a difficult phenomenon to study, particularly in offshore areas, but a wide range of taxa move over or through open water habitats during migration. If we are to understand the potential effects of offshore activities on wildlife populations, we must determine when and where this phenomenon occurs.
We employed several methods to document the timing and routes of animal migration through the mid-Atlantic region, including analysis of weather radar data, the use of avian passive acoustic recorders, satellite telemetry, and boat and aerial surveys.
The Cownose Ray is a species of eagle ray that primarily eats mollusks and shellfish. Large groups of rays migrate north and into inland bays, such as Chesapeake Bay, to breed during summer. While their breeding habits are well known, the migratory period is poorly understood.
Digital video aerial surveys recorded immense migratory schools near the water’s surface in the mid-Atlantic as many as 75 km from shore. We observed almost 48,000 rays in the summer and fall.
Bats are not commonly thought of as offshore migrants, though anecdotal observations of migrating bats over the Atlantic Ocean, particularly in fall, have been reported since at least the 1890s. In September of 2012 and 2013, two bats were sighted during boat-based surveys (one per year), and 15 were documented in high resolution video surveys. All were sighted between 16 and 70 km from shore.
Most of these were identified as Eastern Red Bats, a tree-roosting species that migrates long distances and sometimes collides with land-based wind turbines. Despite their nocturnal habits, these bats were observed flying during the day. Most were estimated to be flying several hundred meters above sea level. Weather conditions were generally good at the time of these observations, suggesting the bats were deliberately migrating offshore rather than having been driven offshore by wind or weather.
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