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2019–2021 Palila abundance estimates and trend

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Title:2019–2021 Palila abundance estimates and trend
Authors:Genz, Ayesha S.
Brinck, Kevin W.
Asing, Chauncey K.
Berry, Lainie
Camp, Richard J.
show 1 moreBanko, Paul C.
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Keywords:abundance estimation
Bird surveys
Hawaii--Hawaii Island
Hawaii--Mauna Kea
show 2 morepoint-transect sampling
trend detection
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Date Issued:24 Jan 2022
Series:HCSU Technical Report Series;101
Abstract:The palila (Loxioides bailleui) population on Mauna Kea Volcano, Hawai‘i Island, was estimated from annual surveys in 2019−2021, and a trend analysis was performed on survey data from 1998−2021. The 2019 population was estimated at 1,030−1,899 birds (point estimate: 1,432), the 2020 population was estimated at 964−1,700 birds (point estimate: 1,312), and the 2021 population was estimated at 452−940 birds (point estimate: 678). Since 1998, a visual inspection of the size of the area containing palila detections on the western slope based on the minimum/maximum elevations has not shown a substantial change, indicating that the range of the species has remained stable; although this area represents only about 5% of its historical extent. During 1998−2005, palila numbers fluctuated between 4,000 and 6,000, followed by a steep decline. After 2010, palila estimates stabilized around an abundance of 2,000 with a much slower rate of decline. The decline during 1998−2021 was on average 229 birds per year with very strong statistical support for an overall downward trend in abundance. Over the 23-year monitoring period, the estimated rate of change equated to an 89% decline in the population.
Description:Biological sciences technical report
Pages/Duration:20 pages
Rights:Attribution-NonCommercial-NoDerivs 3.0 United States
Appears in Collections: Hawaii Cooperative Studies Unit (HCSU)

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