US Fish & Wildlife Service

 

Date of this Version

5-15-2007

Citation

U.S. Fish and Wildlife Service Migratory Birds and State Programs Mountain-Prairie Region Lakewood, Colorado.

Comments

U. S. government work.

Abstract

Observers counted 4,701 swans (white birds and cygnets) in the Rocky Mountain Population of trumpeter swans during January and February 2007, a decrease of 14% from the 5,484 counted during winter 2006. However, in Montana, aerial surveys were conducted only in a portion of the survey area; ground counts were conducted on remaining areas. The numbers of white birds (3,660) and cygnets (919) decreased 14% and 25%, respectively, from counts last year, although these declines are biased high due to a number of birds in Idaho not being classified as either white birds or cygnets. In the tri-state area, decreases in total swans occurred in Montana (-44%) and Idaho (-14%), but increased (+14%) to a record-high count for the third consecutive year in Wyoming. The number of birds wintering in areas near restoration flocks was the highest since 2001, due largely to a 67% increase in the number of swans counted at the Summer Lake Wildlife Management Area. A record low number of swans was counted at Malheur National Wildlife Refuge, while the number of birds at Ruby Lake NWR increased slightly. Reservoir levels in early February increased 11% from levels during 2006, and were 8% above the long-term average. Generally, temperatures in the tri-state area during winter 2006-07 were average or slightly warmer than average, and precipitation was below average.

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