Presentation Abstract
The Marbled Murrelet, Brachyramphus marmoratus, is a federally listed alcid that forages in nearshore waters of the Pacific Northwest, and nests in adjacent older-forest conifers within 40-80 km of shore. To estimate abundance and distribution of murrelets, we conduct at-sea surveys from May to July each year, starting in 2000 and continuing to present. We record numbers of individuals sighted by using distance-based transects and compute annual estimates of density after adjusting for detectability. At-sea transects are subdivided into 5-km segments, and we summarized mean and variance of density at each segment in Puget Sound and along the coast from the Canadian border South to San Francisco Bay. We used a boosted regression tree analysis to investigate the contributions of marine and terrestrial attributes on murrelet abundance in each segment. We observed that terrestrial attributes, especially the amount and pattern of suitable nesting habitat in proximity to each segment, made the strongest contribution, but that marine attributes also helped explain variation in murrelet abundance. Hotspots of murrelet abundance therefore reflect not only suitable marine foraging habitat but proximity of suitable inland nesting habitat.
Session Title
Session S-05D: Marine Birds and Mammals of the Salish Sea: Identifying Patterns and Causes of Change - II
Conference Track
Species and Food Webs
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
1-5-2014 10:30 AM
End Date
1-5-2014 12:00 PM
Location
Room 611-612
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)
Marbled murrelet--Habitat--Northwest, Pacific; Marbled murrelet--Monitoring--Northwest, Pacific
Geographic Coverage
Salish Sea (B.C. and Wash.); Northwest, Pacific
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
Included in
Spatio-temporal dynamics of Marbled Murrelet hotspots during nesting in nearshore waters along the Washington to California coast
Room 611-612
The Marbled Murrelet, Brachyramphus marmoratus, is a federally listed alcid that forages in nearshore waters of the Pacific Northwest, and nests in adjacent older-forest conifers within 40-80 km of shore. To estimate abundance and distribution of murrelets, we conduct at-sea surveys from May to July each year, starting in 2000 and continuing to present. We record numbers of individuals sighted by using distance-based transects and compute annual estimates of density after adjusting for detectability. At-sea transects are subdivided into 5-km segments, and we summarized mean and variance of density at each segment in Puget Sound and along the coast from the Canadian border South to San Francisco Bay. We used a boosted regression tree analysis to investigate the contributions of marine and terrestrial attributes on murrelet abundance in each segment. We observed that terrestrial attributes, especially the amount and pattern of suitable nesting habitat in proximity to each segment, made the strongest contribution, but that marine attributes also helped explain variation in murrelet abundance. Hotspots of murrelet abundance therefore reflect not only suitable marine foraging habitat but proximity of suitable inland nesting habitat.
