LE3 .A278 2022

2022

Craik, Shawn
Mallory, Mark

Acadia University

Master of Science

Masters

Biology

Biology

American common eider (Somateria mollissima dresseri) populations in eastern North America have declined in recent years, and it is believed that this decline is linked to various environmental stressors across the subspecies’ range. To evaluate where to focus future research to help conserve American common eiders, I used a two-step approach. First, a workshop was held to share current knowledge on the status of, and threats to, eiders in the many administrative jurisdictions of the subspecies’ range. Second, I administered a questionnaire to various experts (e.g., government and university biologists, resource managers) across the American common eider range to assess what stages of the annual cycle should be prioritized for future research. Experts recommended that research and conservation tools be implemented particularly for the migration and wintering stages of the eider annual cycle, with breeding stages remaining issues as well. In Nova Scotia, experts agreed that avian predation (e.g., large gulls and raptors) on eider nests has increased in recent years. One conservation tool that may help alleviate predation is the deployment of nest shelters. Accordingly, I assessed nest shelters as a conservation tool for nesting females by examining occupancy rates and microclimate in two shelter types (wooden A-frames and plastic barrels) in eastern Nova Scotia. The proportion of shelters used by nesting American common eiders was similar between the two shelter types, although shelter occupancy rates varied considerably among islands. I found that wooden A-frame shelters more closely mimicked temperature and humidity in natural eider nesting habitat than plastic barrel shelters which created hot and dry conditions that may be cause for concern for the health of nesting hens (e.g., possibility of dehydration based on conversations with veterinarians). The wooden A-frame shelters examined in this thesis provide a suitable microclimate for eider nesting, suggesting that these shelters hold promise as a tool for eider conservation. A next step is to assess whether A-frame shelters can serve to reduce rates of nest predation relative to that in natural nesting habitat, particularly because avian predation remains a key issue to eider population dynamics. Eiders have a cultural significance to many Indigenous peoples, conservation organizations, and local hunters, and are a key bioindicator of the health of marine ecosystems. Bringing experts together was timely for identifying that more work must be done during the non-breeding season.

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https://scholar.acadiau.ca/islandora/object/theses:3737