Sampling locations for occurrence of natural nest cavities in montane ohia trees in Hawaii Volcanoes National Park
Dates
Publication Date
2018-03-23
Start Date
2017-12-27
End Date
2017-12-28
Citation
Judge, S.W. and Camp, R.J., 2018, HAVO Montane Ohia Diameter and Cavity Data 2017: U.S. Geological Survey data release, https://doi.org/10.5066/F7S181SV.
Summary
We quantified the availability of breeding habitat of the endangered Hawaii Akepa (Loxops coccineus). The species is thought to nest excusively in natural cavities within mature ohia (Metrosideros polymorpha) trees but birds commonly occur in short stature trees that presumably do not have any natural cavities because of their polyploidal (many-branched) structure. To test this hypothesis we searched for cavities in trees where akepa forage and we measured diameter of each stem of each tree examined. The habitat is in montane areas of Hawaii Volcanoes National Park on Mauna Loa volcano.We surveyed 57 plots, 49 in montane woodland and 8 in closed-canopy forest. Six tree cavities were detected in the 214 sampled trees: five cavities [...]
Summary
We quantified the availability of breeding habitat of the endangered Hawaii Akepa (Loxops coccineus). The species is thought to nest excusively in natural cavities within mature ohia (Metrosideros polymorpha) trees but birds commonly occur in short stature trees that presumably do not have any natural cavities because of their polyploidal (many-branched) structure. To test this hypothesis we searched for cavities in trees where akepa forage and we measured diameter of each stem of each tree examined. The habitat is in montane areas of Hawaii Volcanoes National Park on Mauna Loa volcano.We surveyed 57 plots, 49 in montane woodland and 8 in closed-canopy forest. Six tree cavities were detected in the 214 sampled trees: five cavities were found in 38 trees sampled in closed canopy forest (8.9/ha) and only one cavity was found in 176 trees sampled in montane woodland (0.29/ha). Tree diameters in the forest ranged from 10 cm to 128 cm diameter at breast height (DBH), while those in the woodland were much smaller ranging from 10 cm to a maximum DBH of 54 cm. Most trees in the closed-canopy forest were monopodial (87%, mean number of stems per tree = 1.16, SE = 0.07) with only five of the 38 trees having multiple stems at DBH height. In contrast, most trees in the woodland were sympodial (61%, mean number of stems per tree = 2.11, SE = 0.11) where 108 of the 176 trees had multiple stems. This CSV file contains the sampling location coordinates for each station in projected UTM coordinates, as well as latitude and longitude. Precise plot locations are regularly spaced at 50-meter intervals between sampling stations, and can be determined mathematically if desired.
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HAVO Montane Ohia Diameter and Cavity Locations.xml Original FGDC Metadata
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HAVO Montane Ohia Tree DBH and Cavity Locations.csv
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text/csv
Related External Resources
Type: Related Primary Publication
Judge, S. W., Camp, R. J., Hart, P. J. and Kichman, S. T. (2018), Population estimates of the Endangered Hawaiʻi ʻĀkepa (Loxops coccineus) in different habitats on windward Mauna Loa. J. Field Ornithol., 89: 11–21. doi:10.1111/jofo.12243
The endangered Hawaii Akepa nests in natural cavities in mature old-growth native ohia (Metrosideros polymorpha) trees, but the species was commonly detected in short stature ohia that presumably have fewer cavities. We quantified the occurrence of natural cavities in short stature ohia trees in montane woodland to assess the potential for nesting habitat for the Hawaii Akepa. This CSV provides coordinates to identify the sampling locations.
