INTRODUCTION 



The Harlequin duck ( Histrionicus histrionicus ) is in the 

 Tribe Merqini . the Sea Ducks, and is our only "torrent" duck in 

 North America. Torrent refers to the harlequin's utilization of 

 fast moving streams. Kuchel (1977) and Wallen (1987) describe 

 the morphological and behavioral similarities between harlequin 

 ducks and two other torrent ducks; the South American torrent 

 duck ( Merqanetta armata ) and the New Zealand blue duck 

 ( Hymenolaimus ma lacorhynchos ) . Those are the known duck species 

 that use fast flowing mountain streams and have similar feeding 

 habits. There is also the American Dipper ( Cinclus mexicanus ) 

 that likewise feeds on insects in swift mountain streams of North 

 Ameri ca . 



The harlequin is the only torrent duck species occupying the 

 northern North American mountain streams at the time of its 

 breeding and nesting season. The American Dipper is also 

 present, but it is not known to compete with the harlequin. 

 Thus, the harlequin evolved to utilize a unique food source with 

 little competition, except for what might occur with fish and the 

 American Dipper, for rapid development during their four to five 

 month brood rearing period. 



Two populations of harlequin ducks have developed from past 

 studies. One population winters on the Northern Atlantic Coast 

 and the other on the Northern Pacific Coast. I concentrate on 

 the Northern Pacific coast population that may winter along the 

 western coast from central California up to the Aleutian Islands 



