By their very nature, seabirds embody the complexity of wildlife ecology and conservation in the 21^st century. They cross distinct ecological boundaries on a regular basis to forage and transit through international waters on a daily, weekly, or monthly time frame. The wide-ranging and transboundary nature of seabird ecology exposes these species to various environmental and anthropogenic forces such as contamination, commercial fishing, and climate forcing that also are transboundary in nature. As such, seabirds represent a unique research and management challenge that require large-scale studies, multi-partner support, and international cooperation. Since 2008, the South Carolina Cooperative Fish & Wildlife Research Unit has been conducting research on the movement patterns of seabirds that breed in the Caribbean and Gulf of Mexico with the aim of gathering data that can be used by agencies such as the U.S. Fish & Wildlife Service, Bureau of Ocean Energy Management, and state/provincial agencies to inform marine spatial planning efforts both in the U.S. and throughout the region.

The 800+ islands of the Caribbean and the Gulf of Mexico support approximately 25 breeding species of seabirds on over 700 colonies governed by approximately 40 nations. However, little to no data are available on movement patterns, timing of movements, extent of wintering or breeding foraging ranges, or overlap of use areas among species from either within or outside of the Caribbean and Gulf breeding populations. The South Carolina CRU research uses a variety of tracking technologies including satellite tags, GPS tags, and geolocators to discern movement patterns and habitat use from days to years. Our efforts began with Audubon's Shearwaters and White-tailed Tropicbirds that breed in The Bahamas. Since then we have expanded to include Masked Booby, Red-Billed Tropicbird, Magnificent Frigatebird, and Brown Pelican and breeding locations including Jamaica, British Virgin Islands, St. Eustatius, Tobago, Campeche Banks in Mexico, and the U.S. states in the northern Gulf of Mexico. Each project is conducted with local partners.

Although still preliminary in nature, our results are changing the way we think about movements of these seabirds during both the breeding and nonbreeding periods. For example, both Audubon's Shearwaters and White-tailed Tropicbirds winter as far north as 45 degrees latitude (i.e., they migrate north to colder, more productive waters following the breeding season). Shearwaters appear to use areas along the edges of the Gulf Stream often moving into U.S. waters while White-tailed Tropicbirds tend to occur in deep pelagic waters far to the east of the stream. Interestingly, both locations appear to be associated with reliable concentrations of Sargassum, a free-floating macroalgae that tends to support small forage fish. Our data from Masked Boobies in Jamaica have demonstrated that individuals from that colony can disperse to waters and colonies in the Gulf of Mexico while data from Brown Pelicans breeding in the northern Gulf have clearly linked these breeding areas to wintering sites in Mexico (Gulf, Caribbean, and Pacific coasts), Central America, and Cuba. Most recently, data from Tobago have demonstrated that shearwaters and Red-billed Tropicbirds that nest there winter off the coast of northern South America but that some individuals winter east of the Mid-Atlantic ridge between the Azores and the Canary Islands.

Viewed across species and breeding locations, our tracking data are beginning to create an updated, more hemispheric view of seabirds in the Caribbean and Gulf. It is clear that while individual birds may breed in The Bahamas or Jamaica or Florida, and while managers in these locations may take responsibility for colony protection and monitoring, these are not Bahamian or Jamaican or Floridian birds. Their annual ranges, and for most species their weekly ranges, take them across political boundaries at the international or state/provincial level as well as across ecoregional boundaries. For wildlife managers this means that research and management efforts need to be considered at very large spatial scales. For example activities that occur thousands of miles away from the breeding colony such as commercial fisheries, energy development, or even climate change may be impacting population dynamics on colonies where most management and monitoring is focused. As we continue to track seabirds in these regions we expect that our understanding of spatial and temporal linkages between colonies and at-sea locations will improve in such a way that wildlife managers from across the region can collaborate across borders to effectively and efficiently manage this unique wildlife resource.

Each month, the ONB features articles from Cooperative Fish and Wildlife Research Units across the country. Working with key cooperators, including WMI, Units are leading exciting, new fish and wildlife research projects that we believe our readers will appreciate reading about.