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Movements and Home Ranges of Monk Seals in the Main Hawaiian Islands

June 27, 2017

From 2007 to 2014 we deployed GPS phone tags on three of the main Hawaiian Islands to study movements and dive behavior of Hawaiian monk seals.

Hawaiian monk seals (Neomonachus schauinslandi) began recolonizing the main Hawaiian Islands roughly 20 years ago. The species’ abundance is still declining, but the subpopulation in these islands is increasing by 6.5 percent per year. This difference may be due to differences in prey availability or habitat quality between the Northwestern and main Hawaiian Islands, which could be reflected in the movements and behavior of the seals. For example, foraging trip durations may be shorter in areas with higher forage quality. From 2007 to 2014 we deployed GPS phone tags on the islands of Moloka‘i (n = 7), Kaua‘i (n = 6), and O‘ahu (n = 6) to study movements and dive behavior. Foraging trips typically lasted 0.57 d (IQR: 0.34–0.83) and seals traveled 18 km (IQR: 10.2–30.5) per trip. Seals began benthic dives shortly after entering the water, with most dives to depths of 12–32 m. The median 95 percent and 50 percent kernel density isopleths for seals in the main Hawaiian Islands were 149.2 and 23.2 square kilometers, respectively. The duration and distance of foraging trips in the main Hawaiian Islands were shorter than that observed in other studies from the Northwestern Hawaiian Islands, suggesting that foraging habitat is currently better in the main Hawaiian Islands.

Wilson K, Littnan C, Read AJ. 2017. Movements and home ranges of monk seals in the main Hawaiian Islands. Marine Mammal Science. 33(4):1080-96.  https://doi.org/10.1111/mms.12429.

Last updated by Pacific Islands Fisheries Science Center on 06/01/2021

Hawaiian Monk Seal