2021 Tinian Island forest bird abundance estimates
2021 Tinian Island forest bird abundance estimates
Date
2022-05-26
Authors
Camp, Richard J.
Bak, Trevor
Genz, Ayesha S.
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Abstract
The U.S. Navy, through Micronesian Environmental Services, surveyed landbirds in the Military
Lease Area on Tinian Island in May and June 2021 using point-transect distance sampling
methods. There were 2,074 individuals of 14 species detected during 123 point counts. Six
species were detected during >50% of the counts and were observed at relatively high
abundances, while eight species occurred at <50% of the counts and were uncommon to rare.
Densities of native landbirds in the Military Lease Area ranged from the uncommon Mariana
kingfisher (Todiramphus albicilla) at 0.46 birds/ha (95% confidence interval [CI] = 0.33–0.63)
to the very abundant bridled white-eye (Zosterops conspicillatus) at 102.63 birds/ha (95%CI =
86.70–122.91). Most distances recorded during the 2021 Military Lease Area survey were
rounded to distance intervals of 0 and 5. Measuring exact distances of detected animals is
preferable to collecting distances grouped into bins or rounding. Direct comparison with
previously published estimates was not possible because of changes in the sampling frame;
however, densities of six species were greater, two were smaller, and one was similar to the
2008 survey estimates for the Hagoi, Diablo, and Masalog regions. Our findings indicate that
the landbird community in the Military Lease Area appears to be dynamic and resilient.
Description
Technical report
Keywords
abundance estimation,
landbird surveys,
point-transect distance sampling,
Mariana Islands--Tinian
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22 pages
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Attribution-NonCommercial-NoDerivs 3.0 United States
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