Date of this Version
U.S. Department of the Interior, U.S. Fish & Wildlife Service, April 2006.
The abundance and productivity of North American trumpeter swans (Cygnus buccinator) was assessed during the 2005 quinquennial trumpeter swan survey, May 2005-January 2006. The continental estimate of trumpeter swan abundance in 2005 was 34,803, a record-high level since comprehensive surveys were initiated in 1968, and 47% higher than the estimate during the 2000 survey. Abundance estimates for each of North America’s 3 recognized trumpeter swan populations also reached record-high levels during the 2005 survey. Survey biologists estimated that the Pacific Coast Population included 24,928 swans, 42% more than during the 2000 survey. The abundance estimate of Rocky Mountain Population swans during the 2005 survey was 5,228 birds, 43% higher than in 2000. The 2005 survey estimate for the Interior Population was 4,647 swans, an increase of 91% from the estimate in 2000. The age distributions of all swan populations during the 2005 survey ranged from 27% to 31% cygnets, and were higher than the 2000 percentage for each population. We present estimates of average annual growth rates and indices of production for these populations and their component flocks.