Harlequin duck breeding occurrence: 



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 brood-rearing periods not separated by more than 10 km of unsuitable habitat 

 or by 20 km of unoccupied, suitable habitat. 



Probable harlequin duck breeding occurrence: 



Drainages or portions of drainages used by harlequin ducks where breeding is highly 

 suspected, i.e., there have been at least 3 independent pair or female observations within 

 the last 15 years. Comprised of contiguous stream reaches (and portions of lakes, 

 reservoirs, or bays) used during the courtship, nesting, and brood-rearing periods not 

 separated by more than 10 km of unsuitable habitat or by 20 km of unoccupied, suitable 

 habitat. 



Breeding status unknown: 



Drainages or portions of drainages with at least 1 harlequin duck observation but fewer 

 than 3 independent pair or female observations during the breeding season within the last 

 15 years. 



Breeding unlikely: 



Observations of males during migration periods. The male migration periods are before 

 1 5 April and after 5 June in the Northern Columbia Basin and Rocky Mountain Front 

 areas and before 1 May and after 20 June in the Intermountain region. 



Observations of pairs outside the prenesting season. The prenesting season is from 15 

 April - 5 June in the Northern Columbia Basin and Rocky Mountain Front areas and 

 fi-om 1 May - 20 June in the Intermountain area. 



Incidental observations in unsuitable habitat such as ponds or large, low gradient (<1%) 

 rivers not adjacent to known breeding sites, or observations on streams which have been 

 identified as lacking breeding activity (e.g. migratory staging areas or stopovers). 



Applying these criteria to the U.S. Rocky Mountains, there are currently 48 known 

 breeding occurrences (89 streams), 10 probable breeding occurrences (29 streams) and 81 

 streams where breeding status is unknown (Cassirer et al. 1996). 



The breeding status on many streams with Harlequin Duck sightings has not been 

 established in the Rocky Mountains of Montana, Idaho, or Wyoming. In Montana, there are 

 currently 33 Harlequin Duck EOs, and 32 streams where Harlequin Ducks have been observed or 

 reported but on which the breeding status is unknown; these streams have been surveyed 0-5 

 times each (Figure 3, Appendix B). In Idaho, there are currently 16 Harlequin Duck EOs, and 24 

 streams where Harlequin Ducks have been observed or reported but on which the breeding status 

 is unknowTi; these streams have been surveyed 0-5 times each (Cassirer et al. 1996.). In 

 Wyoming, there are currently 8 Harlequin Duck EOs, and 1 7 streams where Harlequin Ducks 



