Population estimates of the Endangered Hawaiʻi ʻĀkepa (Loxops coccineus) in different habitats on windward Mauna Loa
Endangered Hawai‘i ʻĀkepas (Loxops coccineus) are endemic to Hawai‘i island, where they occur in five spatially distinct populations. Data concerning the status and population trends of these unique Hawaiian honeycreepers are crucial for assessing the effectiveness of recovery and management actions. In 2016, we used point‐transect distance sampling to estimate the abundance of Hawai‘i ʻĀkepas in portions of Hawai‘i Volcanoes National Park (HAVO) and the Kaʻū Forest Reserve (KFR) on Mauna Loa volcano. We then compiled the survey data from four other populations to provide a global population estimate. In our HAVO and KFR study area, we mapped habitat classes to determine the population densities in each habitat. Densities were highest (1.03 birds/ha) in open‐canopy montane ʻōhiʻa (Metrosideros polymorpha) woodland. In contrast, densities of the largest ʻĀkepa population on Mauna Kea volcano were highest in closed‐canopy ʻōhiʻa and koa (Acacia koa) forest where the species is dependent on nest cavities in tall (> 15 m), large (> 50‐cm diameter at breast height) trees. We surveyed potential nesting habitat in HAVO and KFR and found only one cavity in the short‐stature montane ʻōhiʻa woodland and five cavities in the tall‐stature forest. Differences in densities between the Mauna Kea and Mauna Loa populations suggest that Hawai‘i ʻĀkepas may exhibit different foraging and nesting behaviors in the two habitats. The estimated overall population density in the HAVO and KFR study area was 0.52 birds/ha, which equates to 3663 (95% CI 1725–6961) birds in their 11,377‐ha population range. We calculated a global population of 16,428 (95% CI 10,065–25,198) birds, which is similar to an estimate of 13,892 (95% CI 10,315–17,469) birds made in 1986. Our results suggest that populations are stable to increasing in the two largest populations, but the three other populations are smaller (range = 77–1443 birds) and trends for those populations are unknown.
Citation Information
Publication Year | 2018 |
---|---|
Title | Population estimates of the Endangered Hawaiʻi ʻĀkepa (Loxops coccineus) in different habitats on windward Mauna Loa |
DOI | 10.1111/jofo.12243 |
Authors | Seth W. Judge, Richard J. Camp, Patrick J. Hart, Scott T. Kichman |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Journal of Field Ornithology |
Index ID | 70196107 |
Record Source | USGS Publications Warehouse |
USGS Organization | Pacific Island Ecosystems Research Center |
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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 searc - Connect