Volume 44, No. 1

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Status and monitoring of Ashy Storm-Petrels Oceanodroma homochroa at Point Reyes National Seashore, 2012-2015


1Pacific Coast Science and Learning Center, Point Reyes National Seashore, 1 Bear Valley Road, Point Reyes Station, California 94956 USA (
2California Institute of Environmental Studies, 3408 Whaler Avenue, Davis, CA 95616, USA
3California Audubon, 220 Montgomery Street, Suite 1000, San Francisco, CA 94104, USA
4Humboldt State University, Department of Wildlife, 1 Harpst Street, Arcata, CA 95521, USA
5Current Address: Carter Biological Consulting, 1015 Hampshire Road, Victoria, BC V8S 4S8, Canada


BECKER, B.H., CARTER, H.R., HENDERSON, R.P., WEINSTEIN, A.M. & PARKER, M.W. 2016. Status and monitoring of Ashy Storm-Petrels Oceanodroma homochroa at Point Reyes National Seashore, 2012-2015. Marine Ornithology 44: 63 - 70

Received 24 November 2015, accepted 12 December 2015

Date Published: 2016/04/15
Date Online: 2017/02/28
Key words: Ashy Storm-Petrel, California, nest, mist-net, Oceanodroma homochroa, Point Reyes


While the largest Ashy Storm-Petrel Oceanodroma homochroa (ASSP) colonies are at offshore islands, small colonies also occur along the mainland coast of northern and central California. We describe past and current monitoring efforts along the coastline of Point Reyes National Seashore, California. From 2012 to 2015, we conducted nest searches and mist netting in late August or early September at the Bird Rock and Stormy Stack colonies, as well as the Point Reyes Headlands. Potential nest sites on Stormy Stack (~17) and Bird Rock (~40) included 4-7 and 3-6 active nests, respectively. These nest numbers were similar to those from past complete surveys at Bird Rock in 1989 and Stormy Stack in 2001, suggesting little change in colony size over time. Birds per capture hour during single nights of mist-netting at Bird Rock in 2012 (1.46) and 2013 (1.44) were lower than on two nights in 1989 (5.47 and 3.08), leading to a higher estimate of 37 pairs in 1989. Two ASSP were also netted at the Point Reyes Headlands in 2013, but no nests were found during limited searches in 2013 and 2015. Standardized long-term monitoring of nests at Bird Rock and Stormy Stack will provide better information on future population trends and conservation issues.


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