US Fish & Wildlife Service
Date of this Version
11-14-2006
Citation
U.S. Fish and Wildlife Service Migratory Birds and State Programs Mountain-Prairie Region Lakewood, Colorado.
Abstract
Observers counted 507 swans (white birds and cygnets) in the U.S. Breeding Segment of the Rocky Mountain Population of trumpeter swans during fall of 2006, slightly below the count from last year (510) but the second-highest count since 1992. The numbers of white birds in the tristate region increased 6%, but the number of cygnets was 16% lower compared to counts in 2005. The numbers of young produced in Montana and Wyoming were 57% and 28% lower, respectively, than those of last year, but the number of young counted in Idaho was 77% higher. The numbers of white birds counted in Montana and Idaho were essentially the same as in fall 2005, whereas the count for Wyoming was 20% higher and a record high for the state. The count for birds at Malheur National Wildlife Refuge (NWR) was approximately the same as that of last year. The count for Nevada was slightly higher than that of 2005, and after five consecutive years of no production, four cygnets were counted at Ruby Lake NWR this fall. The count (6) for the Summer Lake Wildlife Management Area probably was biased low because a relatively small amount of area was surveyed. The Pacific Northwest, including portions of the tri-state area, received 150%-200% of normal precipitation during winter months, which alleviated drought conditions that persisted in the region for much of the last several years. Although hot and dry conditions returned during the summer months, Palmer Drought Indices for areas within the tri-state region were similar to those during summer of 2005, and much improved relative to conditions during 2002-2004.
Comments
U. S. government work.