Ua'u - Hawaiian Petrel
'A'o - Newell's Shearwater
Photo courtesy of Bishop Museum
'Ake'ake - Band-rumped Storm-petrel
To monitor these cryptic nocturnal species we used remote sensing acoustic recorders, called SM4 song meters manufactured by Wildlife Acoustics. These devices were programmed to turn on for a limited time after sunset and before sunrise every night to extend battery life for approximately four months. Each one records 1-minute out of every 5-minutes for a 5-hour period beginning at sunset, then 1-minute out of every 10-minutes for the 5 hours preceding sunrise on every survey night. Sunset and sunrise times were calculated for the point of 19.59N 155.47W.
Photo of a SM4 Song Meter deployed at POU3 site.
Photo of SM4 Song Meter deployed in Mauna Loa Forest Reserve.
We contracted Conservation Metrics Inc. to analyze many gigabytes of recordings. They used custom detection software to classify and elicit seabird vocalizations from the data we collected and issued DOFAW a report in a timely fashion.
Hawaiian Petrels and Newell's Shearwaters were both found using Kohala mountain within the Puu O Umi Natural Area Reserve. Their presence is consistent with the theory that both these colonial species are using this habitat and may represent unique populations of their respective species in Hawaii. Especially for Hawaiian Petrels which had vocal activity consistent with low level breeding aggregations at sites monitored on Kauai.
Hawaiian Petrel call rates measured in calls per minute at six sites in Puu O Umi NAR.
Newell's Shearwater call rates measured in calls per minute at six sites in Puu O Umi NAR.
Band-rumped Storm-petrels were also detected but at very low frequency across all three sites within the Mauna Loa Forest Reserve but not in Puu Maka'ala NAR or Manuka NAR.
Band-rumped Storm-petrel call rates measured in calls per minute.
Hawaiian Petrel activity by date during peak calling hour (40-100 minutes after sunset).
Song meter deployment sites on Hawaii Island. The eight Natural Area Reserves on the Big Island are outlined in yellow and song meters are in red. Three of the song meters were placed in the Mauna Loa Forest Reserve, not a Natural Area Reserve.
Close up of six song meter locations in Puu O Umi NAR.
View of the habitat along Waimanu Valley rim. Where songmeters POU1, POU3 and POU4 were located.
View of habitat where POU2 and POU5 were located.
This was the first time DOFAW had used this type of remote sensing to monitor cryptic seabirds. This is a fresh start to identifying and monitoring populations of these endangered seabirds. With this data we can confirm presence of a moderate sized Hawaiian Petrel population sustaining in Kohala and the presence of Newell's Shearwaters, both of which are not well known on Hawaii Island. The phenology data of Hawiian Petrels in Kohala is especially intriguing as it appears they arrive earlier in the night and earlier in the season than the only other Hawaiian Petrels known on the Big Island, the Mauna Loa population in Hawaii Volcanoes NP. This is suggestive that they are a seperate population and further investigation should be made for genetic differences, and other differences in behavior such as foraging grounds.
The Band-rumped Storm-petrels were previously unknown in the Mauna Loa Forest Reserve. The Hawaii population of this species was just listed as endangered in October 2017. With only two burrows ever found in the state, further monitoring of this species is high priority.
DOFAW is already underway in a second year of remote sensing in both Puu O Umi NAR and Mauna Loa Forest Reserve. We will combine this with in-person nocuturnal surveys using night vision and thermal devices. Our goal is to ultimately find burrows of all these species so that we can better protect them from likely their major threat, mammalian predators.
DOFAW staff with thermal binoculars preparing to survey for petrels at night.