Caspian Tern

Dan Roby, Don Lyons

Latin name: Hydroprogne caspia

Caspian Terns are the largest species of tern, and are very efficient predators on ESA-listed juvenile salmonids during outmigration. Drs. Dan Roby, Don Lyons, and Yasuko Suzuki discovered that the largest colony for the species in the world was on Rice Island in the Columbia River estuary, and fed mostly on millions of salmon. By moving the tern colony from Rice Island to East Sand Island, they were able to reduce salmon predation by more than 60%, while not harming the tern colony.

Did you know? Our group discovered that the Caspian Tern breeding colony in the Columbia River estuary was the largest of its kind in the world, perhaps representing 10% of the global population of the species. One of the Caspian Terns that our group banded as a breeding adult at a colony in San Francisco Bay turned up the next year nesting in a new colony at the mouth of the Copper River in Alaska.


Research Paper

Collis, K., D. D. Roby, D. P. Craig, S. K. Adamany, J. Y. Adkins, and D. E. Lyons. 2002. Colony size and diet composition of piscivorous waterbirds on the lower Columbia River: Implications for losses of juvenile salmonids to avian predation. Transactions of the American Fisheries Society 131:537-550.

Roby, D. D., K. Collis, D. E. Lyons, D. P. Craig, J. Y. Adkins, A. M. Myers, and R. M. Suryan. 2002. Effects of colony relocation on diet and productivity of Caspian terns. Journal of Wildlife Management 66:662-673.

Roby, D. D., D. E. Lyons, D. P. Craig, K. Collis, and G. H. Visser. 2003. Quantifying the effect of predators on endangered species using a bioenergetics approach: Caspian terns and juvenile salmonids in the Columbia River estuary. Canadian Journal of Zoology 81:250-265.

Suryan, R. M., D.P. Craig, D. D. Roby, N. D. Chelgren, K. Collis, W. D. Shuford, and D. E. Lyons. 2004. Redistribution and growth of the Caspian tern population in the Pacific Coast region of North America, 1981-2000. Condor 106:777-790.

Antolos, M., D. D. Roby, D. E. Lyons, K. Collis, A. F. Evans, M. Hawbecker, B. A. Ryan. 2005. Caspian tern predation on juvenile salmonids in the Mid-Columbia River. Transactions of the American Fisheries Society 134:466-480.

Collis, K., D. D. Roby, K. W. Larson, L. J. Adrean, S. K. Nelson, A. F. Evans, N. J. Hostetter, D. S. Battaglia, D. E. Lyons, T. K. Marcella, and A. Patterson. 2012. Trends in Caspian Tern nesting and diet in San Francisco Bay: Conservation implications for terns and salmonids. Waterbirds 35:25-34. 

Adrean, L. J., D. D. Roby, D. E. Lyons, K. Collis, and A. F. Evans. 2012. Potential effects of management on Caspian tern Hydroprogne caspia predation on juvenile salmonids at a colony in San Francisco Bay, California. Transactions of the American Fisheries Society 141:1682-1696.

Patterson, A. G. L., A. S. Kitaysky, D. E. Lyons, and D. D. Roby. 2014. Nutritional stress affects corticosterone deposition in feathers of Caspian tern chicks. Journal of Avian Biology 45:001-007.

Collis, K., D. D. Roby, D. P. Craig, B. A. Ryan, and R. D. Ledgerwood. 2001. Colonial waterbird predation on juvenile salmonids tagged with passive integrated transponders in the Columbia River estuary: Vulnerability of different salmonind species, stocks, and rearing types. Transactions of American Fisheries Society 130:385-396.