US Fish & Wildlife Service
Date of this Version
4-2006
Citation
U.S. Department of the Interior, U.S. Fish & Wildlife Service, April 2006.
Abstract
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.
Comments
U. S. government work.