The distribution, phenology, and prey of harlequin ducks, Historionicus histrionicus, in a Cascade Mountain stream, Oregon

Publication Type:

Journal Article

Authors:

Wright, Kristopher K.; Bruner, Howard; Li, Judith L.; Jarvis, Robert; Dowlan, Steve

Source:

Canadian Field-Naturalist, The Ottawa Field-Naturalists' Club, Volume 114, Issue 2, p.187-195 (2000)

Call Number:

A00WRI01IDUS

URL:

http://www.biodiversitylibrary.org/item/106750#page/199/mode/1up

Keywords:

Harlequin Duck, Histrionicus histrionicus

Abstract:

Wright et al. examined the phenology, abundance, and in-stream habitat use of harlequin ducks (Histrionicus histrionicus) and their primary prey, the caddisfly larvae Dicosmoecus gilvipes, in a Cascade Mountain stream from 1994–1997. Harlequins and D. gilvipes inhabited the stream from late April through late July, and both frequented areas with high proportions of bedrock. When broods were present in late June and July, D. gilvipes made up over 80% of harlequin diets. Although harlequins foraged intensively on D. gilvipes, no direct relationship was found between harlequin distribution and caddisfly abundance at nine 50-m study sites. After a severe flood in early 1996, the authors observed reductions in overall harlequin numbers, a seasonal delay in brood development, and a decrease in abundance of D. gilvipes.