This study evaluated potential disturbance effects caused to Hawaiian monk seals and birds in the Northwestern Hawaiian Islands during flights with an APH-22 hexacopter.
Unmanned Aerial Systems (UAS) have great potential for use in Hawaiian monk seal conservation research, as a non-invasive tool that allows researchers to easily survey hard-to-reach areas.
Possible applications of UAS technology include population count surveys and body condition measurements using photogrammetry.
We investigated whether APH-22 flights disturb target and non-target study species, Hawaiian monk seals and birds.
Behavioral disturbance data was collected during flights of a remotely operated APH-22 hexacopter in the Northwestern Hawaiian Islands during September 2015 and April and May 2018.
Seal behaviors recorded initially and at each altitude
Bird behaviors recorded during 4 flight periods: before flight, during launch, during flight, and during landing
Seal behavioral responses compared by altitude, location, age, and initial behavior
Bird behavioral responses compared by group size, flight period, and species
3 categories of seal behavior: No change, minor behavioral changes, position changes
2 categories of bird behavior: Flushed/did not flush, approached UAS/did not approach
Descriptive plots used to compare seal and bird behavioral responses between groups
Generalized linear mixed-effects model of seal behavior as a function of altitude, location, age, and initial behavior
Model chosen by backwards selection based on AIC score and significance level of individual variables
Behavioral response categories:
Behavioral response observed in Hawaiian monk seals during hexacopter UAS flights
Behavioral Response Categories:
Behavioral response observed in birds during hexacopter UAS flights
Disturbance caused to seals and birds by APH-22 hexacopter flights was minimal, making APH-22 an appropriate tool for future surveys of these species in the Northwestern Hawaiian Islands. Flying with higher resolution cameras will allow researchers to pilot the UAS at higher altitudes and collect the same quality of data with less disturbance.
The results of this study and the capabilities of UAS for studying Hawaiian monk seals remotely and in hard-to-reach locations indicate that UAS are a promising tool for future conservation research.
We would like to thank the teams from the Hawaiian Monk Seal Research Program that conducted UAS flights and collected behavioral data in the Northwestern Hawaiian Islands. Special thanks also to Stacie Robinson and Jessica Bohlander for their guidance and mentorship in this research. Research was conducted under MMPA/ESA permit #16632-00 & 16632-02, PMNM-2015-01 & PNMN-2018-01. This research is supported by the NOAA Hollings Undergraduate Scholarship Program.