Post-breeding ecology of Red-breasted Mergansers in a marine environment

Project Number: 51

Year Funded: 2006

Lead Institution(s): McGill University

Project Lead: Rodger Titman

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Collaborator(s): Jean-Pierre Savard (CWS), Shawn Craik (MGU), Parks CA, NBWTF, DWF, BU

Location: Quebec

Focal Species: Red-breasted Merganser (Mergus serrator)

Project Description: Both Red-breasted (Mergus serrator) and Common (Mergus merganser) mergansers have historically been shot illegally in eastern North America while suspected of foraging on fry of Atlantic Salmon (Salmo salar). Descriptions of distribution and ecology for these two mergansers have often been given together, with more emphasis on the more abundant Common Merganser. As a result, the Red-breasted Merganser has perhaps been unjustly accused of having an impact on commercial fish populations despite the fact that its often separate role in coastal environments during the breeding and post-breeding periods is not well understood. Specifically, identification and characterization of coastal breeding (nest and brood habitat requirements) and molting habitats for Nearctic Red-breasted Mergansers are lacking. Also, little is known of the population dynamics, including nest and brood survival, of mergansers occurring in marine environments.

Studies of breeding mergansers occurred at Kouchibouguac National Park, New Brunswick, Canada from mid-May to mid-September 2002 to 2006. Here, a population of colonial Redbreasted Mergansers nested on 4 small coastal barrier islands. Investigations of molting male mergansers were held throughout the wing molt at 3 coastal bays at the western extremity of Anticosti Island, Quebec, Canada, from early July to mid-September 2005 and 2006.