Volume 51, No. 2

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Medical history and post-release survival of rehabilitated California Brown Pelicans Pelecanus occidentalis californicus, 2009-2019


1International Bird Rescue, 4369 Cordelia Road, Fairfield, California 94534, USA *(
2Pacific EcoLogic, 1151 Lakeview Drive, Crescent City, California 95531, USA
3EH1, 256 Windsor Drive, San Carlos, California 94070, USA


DUERR, R.S., JAQUES, D.H., SELBY, B.G., SKOGLUND, J.S. & KOSINA, S. 2023. Medical history and post-release survival of rehabilitated California Brown Pelicans Pelecanus occidentalis californicus, 2009-2019. Marine Ornithology 51: 157 - 168

Received 31 August 2022, accepted 19 March 2023

Date Published: 2023/10/15
Date Online: 2023/08/03
Key words: California Brown Pelican, Pelecanus occidentalis californicus, rehabilitation, post-release survival, MARK, medical problems


California Brown Pelicans (Pelecanus occidentalis californicus) rehabilitated in 2009–2019 were released with metal federal and blue plastic auxiliary leg bands. Resighting data were obtained from the US Geological Survey’s Bird Banding Laboratory, International Bird Rescue’s citizen science reporting forms, and non-breeding communal roost site surveys. Medical problems and demographic data were assessed in relation to whether birds were resighted, whether they were alive at the most recent resighting, and by longevity after release. The 1418 blue-banded individuals in the study were admitted for rehabilitation and released 1465 times, and 49.9% were resighted at least once. At the most recent re-encounter, 79.2% were alive. Fifty-five birds were not resighted until 5–11 years after release. Mean (± standard deviation) post-release longevity inclusive of all birds was 3 (3.1) years, which represents minimum survival time for those last encountered alive. Survival analysis was performed utilizing annualized resightings and dead recoveries for each bird. Survival probability differed with intake age, averaging 0.70 for birds admitted as post-fledge hatch-year to 0.80 for birds admitted as after-hatch-year. Dedicated surveys beginning in 2015 resulted in a much higher probability of live detections in the latter half of the study. Annual survival estimates averaged 0.83 during this period, when age at rehabilitation was not an important factor. Mean longevity of the 2015–2019 cohort was estimated at 5.67 years post release. Of 224 birds receiving blue bands during 2009–2010, 13.8% of sub-adults or after-third-years at rehabilitation have been resighted older than 10 years of age, including 11 birds resighted since 2021 at minimum ages of 13.1–15.2 years. This study shows that Brown Pelicans can be successfully rehabilitated and returned to the wild, with some demonstrating greater than expected longevity than previously estimated for the species.


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