Ashy Storm-Petrel Oceanodroma homochroa mist-netting and capture rates in the California Channel Islands, 2004–2007

Marine Ornithology: Journal of Seabird Research and Conservation
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Abstract

The California Channel Islands (CCI) provide essential nesting habitat for a significant portion of the world’s Ashy Storm-Petrel Oceanodroma homochroa (ASSP) breeding population, but true abundance at this locality is not well known. Land-based nocturnal mistnetting has been conducted sporadically in the CCI since 1976, with variation in techniques and methods. Using a standardized catch-perunit-effort (CPUE) is one of the few methods available to monitor trends in relative abundance, but there currently are no guidelines for a standardized, repeatable approach for the CCI. During 2004–2007, I conducted mist-netting for ASSP at three colony sites within the CCI: Scorpion Rock (SR), Santa Barbara Island (SBI), and Prince Island (PI). During 47 site-nights (22 sessions), I obtained 1 177 unique captures, including 34 recaptures (2.9%) of previously banded individuals. ASSP captured at all three islands showed peak proportions of fully developed incubation patches in July and August. ASSP captured in the CCI had 5%–9% lower body mass than individuals captured off central California during the early 1970s; it is not known whether this difference reflects natural inter-annual variation or differences in body condition. ASSP from SBI had the lowest body condition index (BCI) compared with those from PI and SR, indicating different foraging environments. Overall, 22 netting-sessions at three islands yielded a power of 84% to detect a 30% lesser CPUE; 19 sessions would be required in a future effort to evaluate this level of change. Evaluation of additional factors that affect CPUE and other independent measures of abundance or attendance should be included in future mist-netting efforts.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Ashy Storm-Petrel Oceanodroma homochroa mist-netting and capture rates in the California Channel Islands, 2004–2007
Series title Marine Ornithology: Journal of Seabird Research and Conservation
Volume 44
Issue 1
Year Published 2016
Language English
Publisher Marine Ornithology
Contributing office(s) Western Ecological Research Center
Description 12 p.
First page 71
Last page 82
Country United States
State California
Other Geospatial California Channel Islands, San Miguel Island, Santa Barbara Island, Santa Cruz Island
Online Only (Y/N) N
Additional Online Files (Y/N) N