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STANDARDIZED MONITORING OF ASHY STORM-PETREL CAPTURE-RECAPTURE RATES IN THE CHANNEL ISLANDS NATIONAL PARK

Released: 2015
Citation:
Adams, J. 2015. STANDARDIZED MONITORING OF ASHY STORM-PETREL CAPTURE-RECAPTURE RATES IN THE CHANNEL ISLANDS NATIONAL PARK. Special Session 4: Ashy Storm-Petrel Rangewide Science and Conservation, Pacific Seabird Group, 42nd Annual Meeting, 18-21 February 2015, San Jose, CA. [Invited Oral Presentation]

 

Channel Islands National Park (CINP) provides essential nesting habitat for greater than half the world’s population of breeding Ashy Storm-Petrel (Oceanodroma homochroa). Currently, information is required to maintain, enhance, and standardize Ashy Storm-Petrel monitoring to determine trends in relative population size. Since 1975, capture-recapture efforts at various sites using mist-netting methods were conducted sporadically using varying techniques (i.e., mist-netting with and without broadcast vocalizations). No formal guidelines exist describing a standardized, repeatable approach. During 2004-07, I conducted mist-netting surveys (47 site-nights) targeting Ashy Storm-Petrels at three colony sites: Scorpion Rock off Santa Cruz Island, Santa Barbara Island, and Prince Island off San Miguel Island. I recorded 1,178 unique Ashy Storm-Petrel captures with 35 (2.9%) recaptures of previously banded storm-petrels. Power to detect 30% lesser mean standardized catch per unit effort (CPUEs) at equivalent sample size and alpha = 0.15 (85% CI), was variable across islands and years, from 39% (Prince Island 2005) to 87% (Santa Barbara Island 2005). Overall, based on CPUEs, I estimated power = 96% to detect a 30% lesser CPUEs. Five to 42 site-nights at individual islands/years, or a minimum 21 site-nights across islands would be required to achieve 80% power to detect a 30% lesser CPUEs. Among relatively dark nights, moon index did not significantly affect capture rate. Proxy wind-speed also did not significantly affect capture rate. CPUEs can be further improved and used for evaluating trends in relative abundance—essential for tracking conservation status and restoration efforts aimed at providing a future for Ashy Storm-Petrel.



This product is associated with the following project:
Summary of Seabird Studies at WERC

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