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Seabird Monitoring Program to Study Tern Die-Offs

Common tern chicks

Tufts Cummings School-based SEANET and Mass Audubon's Coastal Waterbird Program receive grant from Massachusetts Wildlife Trust License Plate Initiative.

Mass Audubon has partnered with US Fish and Wildlife Service, and SEANET, the Seabird Ecological Assessment Network based at Tufts University's Cummings School of Veterinary Medicine. SEANET received a nearly $30,000 from the Massachusetts Environmental Trust to study why massive numbers of state-listed Common Terns died near the Monomoy National Wildlife Refuge between 2004 and 2006-and how similar mortalities might be avoided in the future.

Earlier studies by the National Wildlife Health Center and the Cummings School determined that the 500 to 2,000 fledgling terns died from massive infections by Salmonella enterica serovar Typhimurium from July, 2004 to August, 2006. Wild bird mortality events caused by S. Typhimurium infections are not uncommon; however, no previous outbreaks of this magnitude and regularity have been reported at any tern colony in Massachusetts or the rest of North America. Monomoy NWR is home to one of the two largest Common Tern colonies in North America, with 8,000-10,000 pairs breeding there each year. Such large die-offs of fledglings are a major concern for the productivity of this important breeding colony.

The cause of the Salmonella outbreak and resultant tern die-off at Monomoy NWR is unknown. No outbreaks of salmonellosis and no major die-offs of terns have occurred during the same period of time at any other Common Tern colony at Cape Cod, suggesting that this phenomenon is unique to Monomoy NWR. SEANET researchers suspect the outbreaks could be linked to a variety of point and non-point sources in the region.

Becky Harris, PhD, Director of Massachusetts Audubon's Coastal Waterbird Program worked with SEANET Program Director Julie Ellis, PhD and Monomoy NWR staff to gather environmental samples from around the Monomoy NWR nesting site, and are collaborating with Dr. Steve Jones of the University of New Hampshire's Ribotyping Laboratory to identify areas that may be possible sources of the Typhimurium strain. In a second phase of the project, these researchers will collaborate with state, local, and federal officials to mitigate Typhimurium levels around the Monomoy refuge. The funding for the Massachusetts Environmental Trust grant comes from a statewide license plate campaign through the Registry of Motor Vehicles.

"The Common Tern die-off of 2004-2006 remains a major unsolved mystery of New England wildlife science," said Dr. Julie Ellis, PhD, director of the SEANET program. "We hope that by identifying the source of Typhimurium and working to eradicate it, we can help prevent another die-off to this already endangered species." E. Coli and Salmonella were isolated from tern feces and environmental samples, and results from ribotyping are forthcoming.

To find out more about Monomoy NWR, visit: www.fws.gov/northeast/monomoy.

Visit Massachusetts Environmental Trust on the web.