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Forest bird populations at the Big Island National Wildlife Refuge Complex, Hawai‘i

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TR102_Kendall_2022_Forest bird populations at BINWRC_Appendix2.xlsx Excel datasheet 61.33 kB Microsoft Excel XML View/Open
TR102_Kendall_2022_ Forest Birds at BINWRC.pdf Adobe file 9.09 MB Adobe PDF View/Open

Item Summary Kendall, Steven J. Rounds, Rachel A. Camp, Richard J. Genz, Ayesha S. 2022-04-13T07:57:22Z 2022-04-13T07:57:22Z 2022-04-13
dc.description Technical report with figures and tables and ancillary Excel data file.
dc.description.abstract Endemic Hawaiian forest birds have experienced dramatic population declines. The Big Island National Wildlife Refuge Complex (BINWRC) was created for conservation of endangered Hawaiian forest birds and their habitats. Surveys have been conducted at two units of BINWRC to monitor forest bird populations and their response to management actions. We analyzed survey data from 1987 to 2019 at the Hakalau Forest Unit (HFU) and from 1995 to 2019 at the Kona Forest Unit (KFU). We analyzed three strata at HFU: open-forest, closed-forest, and pasture, and two strata at the KFU: upper (>1524 m elevation) and lower (<1524 m). In all years, ‘i‘iwi (Drepanis coccinea), ‘apapane (Himatione sanguinea), and Hawai‘i ‘amakihi (Chlorodrepanis virens virens) were the most abundant species at HFU. The three endangered forest bird species, Hawai‘i ‘ākepa (Loxops coccineus), ‘alawī (Loxops mana, also known as Hawai‘i creeper) and ‘akiapōlā‘au (Hemignathus wilsoni), had much lower densities. The most abundant species at KFU was ‘apapane, followed by Hawai‘i ‘amakihi and warbling white-eye (Zosterops japonicus) at much lower densities. At HFU we found a continuation of several trends observed in previous analyses from 1987–2012, with most species’ trends upward in pasture stratum, stable in the open-forest stratum, and downward in the closed-forest stratum. However, when we looked at the most recent decade at HFU, more species were showing downward trends in all three strata. At KFU results were mixed, with more species’ trends downward in the upper stratum and more species’ trends upward in the lower stratum. Populations of endangered forest species were either locally extirpated at KFU or in numbers too low to reliably estimate population densities. Both units in the BINWRC are important for conservation of forest birds on Hawai‘i Island, and our results show that HFU supports the majority of the three endangered forest bird species found on Hawai‘i Island. Our analysis also shows the importance of continuous monitoring and timely analysis to track forest bird populations. With the additional data provided by continued surveys, we determined conclusive population trends for species whose trends were previously inconclusive. Knowing current population densities, abundances, and trends allows managers to evaluate and adapt management actions to support forest bird conservation at the BINWRC.
dc.format.extent 141 pages
dc.language.iso en-US
dc.relation.ispartofseries HCSU Technical Report Series;102
dc.rights Attribution-NonCommercial-NoDerivs 3.0 United States
dc.subject Big Island National Wildlife Refuge Complex
dc.subject Bird counts
dc.subject Hawaii--Hakalau Forest National Wildlife Refuge
dc.subject Hawaii
dc.subject Hawaiian forest birds
dc.subject Kona Forest Unit
dc.subject Point-transect distance sampling
dc.subject Population trends
dc.title Forest bird populations at the Big Island National Wildlife Refuge Complex, Hawai‘i
dc.type Technical Report
dc.type.dcmi Text
Appears in Collections: Hawaii Cooperative Studies Unit (HCSU)

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