brood- rearing periods not separated by more than 10 km of unsuitable habitat or 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 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 15 

 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 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). 



Using these criteria, there are currently 48 known breeding occurrences (89 streams), 10 

 probable breeding occurrences (29 streams) and 81 streams where breeding status is unknown in the 

 Rocky Mountains (Table 2, Fig. 2, Appendices A, B,and C, Table 1). Data are more complete for 

 Idaho and Montana than for Wyoming. As of 1995, inventory had been conducted on approximately 

 5,640 km of stream (Idaho - 1,886 km; Wyoming - 792 km; Montana 2963 km). Wyoming 

 distribution outside Yellowstone and Grand Teton National Parks is based 1 season of surveys (Laurion 

 and Oakleaf 1995), and observations as well as historical observations and data in the Wyoming Game 

 and Fish Department and Natural Heritage Program databases. 



