Table 1. Documented use of streams during the breeding season by harlequin ducks in the 

 Pacific population in the coterminus United States, 1995. 



State Number of breeding streams Number of harlequin duck 



or possible breeding streams breeding or probable 

 where harlequin ducks have breeding occurrences' 

 been observed 



Washington 164 



Oregon 39 



Idaho 54 16 



Montana 102 33 



Wyoming 40 8 



California 1 - 



Total 400 



i 



Data on harlequin duck breeding occurrences (defined below) not available outside the U.S. Rocky 



Mountains. 



Within the U.S. Rocky Mountain area harlequin duck breeding streams can be divided into 2 

 subprovinces based on breeding ecology, habitat characteristics and geographic separation: 



1 . Northern Columbia Basin - northwestern Montana, including Glacier National Park and the 

 Rocky Mountain Front, and Idaho north of the Salmon River. 



2. Intermountain - southern Idaho north to and including the Salmon River, southwestern 

 Montana and all of Wyoming including the Greater Yellowstone area. 



Not all streams used by harlequin ducks during the breeding season are used for nesting or 

 brood-rearing. Some streams where adult harlequins are observed may be used only during migration 

 to and from breeding areas (these streams are not included in Table 1). In order to classify harlequin 

 duck observations in a consistent manner, we propose the following criteria: 



Harlequin duck breeding occurence: 



Drainages or portions of drainages used by harlequin ducks where breeding is known, i.e. a 

 brood or nest has been observed within the last 15 years. Comprised of contiguous stream 

 reaches (and portions of lakes, reservoirs, or bays) used during the courtship, nesting, and 



