Application of lidar for critical endangered bird species conservation on the island of Kauai, Hawaii

The Akikiki (Oreomystis bairdi) and Akekee (Loxops caeruleirostris) are two honeycreepers endemic to Kauai, Hawaii, that were listed as federally endangered in 2010. Both species are rare, little-studied, and occur in a remote, roadless area. We analyzed high-resolution airborne lidar data to identify forest structure and topography metrics associated with Akikiki and Akekee nest locations (88 for Akikiki and 22 for Akekee) and occurrences (3706 for Akikiki and 1581 for Akekee) from 2012 to 2017 on the Alakai Plateau to predict their distribution in unsurveyed areas. Akikiki and Akekee nested in areas with similar forest structure at 10 m resolution, but different maximum tree heights. Akikiki and Akekee foraged in areas with significantly different forest structure (maximum tree height, mean canopy height, relative heights) and topography (slope) based on occurrences. Elevation was consistently one of the most important metrics for predicting both species nest locations and occurrences across scales (10, 100, 250 m) and it appears that both species are at the upper limits of their elevational range. We estimate that the area of suitable nesting habitat for Akikiki is 17.59 km(2) while the area of suitable nesting habitat for Akekee is 11.10 km(2) at 10 m resolution. The Akikiki has a potential range of 38 km(2) while the Akekee has a range of 58 km(2) at 100 m resolution. We produce predictive nest and occurrence maps at 10 m and 100 m resolutions to spatially target conservation actions. Results suggest that if avian malaria cannot be controlled and both species populations do not stabilize over the coming years, translocation may be needed to insure their viability.

Automated summary

This study analyzed the habitat preferences and distribution patterns of the endemic honeycreepers Akikiki and Akekee in Kauai, Hawaii, revealing that they are at the upper limits of their elevational range and may require translocation to ensure their viability in the face of avian malaria and unstable populations.