What’s happening with Harlequin ducks in the Salish Sea?
Presentation Abstract
White Rock B.C. supports a relatively small population of Harlequin ducks during the non-breeding period. From the 1980s to the mid-2000s, males consistently returned to White Rock during June-July to complete their body and wing molts, followed by females 1-2 months later. However, by 2006 all males stopped molting at White Rock, returning instead 2+ months later in pre-alternate plumage. Associated with this change in behavior the number of overwintering males declined and this contributed to a local population level effect. Causal factors are unknown but the following are suspected: 1) increasing levels of disturbance from kayakers and paddle-boarders, and/or 2) increasing levels of predation risk from river otters and bald eagles. Surveys were initiated at two nearby sites (Point Roberts and Birch Bay in WA State) to determine if the same pattern of delayed return is occurring, and that definitely seems to be the case. In spring 2015 we marked Harlequin ducks at White Rock (7M/7F) and Hornby Island (14M/8F) with satellite transmitters to describe winter-breeding affiliations and site-fidelity, and to track male molt migration patterns. The resulting Argos data showed that the large majority of the tagged birds bred in the Rocky Mountain-Kootenay Mountain region, all signaling birds returned to their capture sites by the end of October indicating a high level of site-fidelity, and the males migrated north of the Salish Sea to molt, from northern Vancouver Island to Prince Rupert BC. This large-scale molt migration was unexpected and raises the following questions: Why is it occurring? Is it happening throughout the Salish Sea? Is this a recent phenomenon or has it always occurred? Finally, what are the population implications for Harlequin ducks and other marine birds in the Salish Sea? Plans are to mark breeding birds in Alberta and northern US Sates to further describe connectivity and migration patterns.
Session Title
Local Stories and Results
Keywords
Key words: Harlequin ducks, migration, satellite transmitters, molting, breeding, connectivity.
Conference Track
Salish Sea Snapshots
Conference Name
Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)
Document Type
Event
Start Date
2016 12:00 AM
End Date
2016 12:00 AM
Location
2016SSEC
Type of Presentation
Snapshot
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Harlequin duck--Seasonal distribution--Salish Sea (B.C. and Wash.)
Geographic Coverage
Salish Sea (B.C. and Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
What’s happening with Harlequin ducks in the Salish Sea?
2016SSEC
White Rock B.C. supports a relatively small population of Harlequin ducks during the non-breeding period. From the 1980s to the mid-2000s, males consistently returned to White Rock during June-July to complete their body and wing molts, followed by females 1-2 months later. However, by 2006 all males stopped molting at White Rock, returning instead 2+ months later in pre-alternate plumage. Associated with this change in behavior the number of overwintering males declined and this contributed to a local population level effect. Causal factors are unknown but the following are suspected: 1) increasing levels of disturbance from kayakers and paddle-boarders, and/or 2) increasing levels of predation risk from river otters and bald eagles. Surveys were initiated at two nearby sites (Point Roberts and Birch Bay in WA State) to determine if the same pattern of delayed return is occurring, and that definitely seems to be the case. In spring 2015 we marked Harlequin ducks at White Rock (7M/7F) and Hornby Island (14M/8F) with satellite transmitters to describe winter-breeding affiliations and site-fidelity, and to track male molt migration patterns. The resulting Argos data showed that the large majority of the tagged birds bred in the Rocky Mountain-Kootenay Mountain region, all signaling birds returned to their capture sites by the end of October indicating a high level of site-fidelity, and the males migrated north of the Salish Sea to molt, from northern Vancouver Island to Prince Rupert BC. This large-scale molt migration was unexpected and raises the following questions: Why is it occurring? Is it happening throughout the Salish Sea? Is this a recent phenomenon or has it always occurred? Finally, what are the population implications for Harlequin ducks and other marine birds in the Salish Sea? Plans are to mark breeding birds in Alberta and northern US Sates to further describe connectivity and migration patterns.
Comments
Key words: Harlequin ducks, migration, satellite transmitters,molting, breeding, connectivity.