ANTI-CYCLONIC CIRCULATION AND THE LONG-RANGE FORAGING MOVEMENTS OF HAWAI´IAN PETRELS (PTERODROMA SANDWICHENSIS) IN THE NORTH PACIFIC Josh Adams*1, David G. Ainley2, Jay F. Penniman3, Cathleen Bailey4, Joy Tamayose4, Fern Duvall5, and Holly Freifeld6 1U. S. Geological Survey, Western Ecological research Center, 400 Natural Bridges Dr, Santa Cruz, CA 95060,
[email protected]; 2HT Harvey and Associates, San Jose, CA; 3Pacific Cooperative Studies Unit, University of Hawaii, Honolulu, HI; 4Haleakala National Park, Makawao, HI; Hawaii Division of Forestry and Wildlife, Kahului, Maui, HI, U. S. Fish & Wildlife Service Satellite telemetry studies of the movements of seabirds are now common and have revealed impressive flight capabilities and extensive distributions among individuals of many species at sea. Linking seabird movements with environmental conditions over vast expanses of the world’s open ocean, however, remains difficult. We applied a new method for quantifying the movements of far-ranging seabirds in relation to ocean winds measured by the SeaWinds scatterometer onboard the QuikSCAT satellite. We apply vector correlation to evaluate how the trajectories (ground speed and direction) of Hawaiian Petrels outfitted with satellite transmitters during the summer chick-rearing period were related to ocean winds. During three consecutive breeding seasons (2006–08), 17 birds from two colonies (Maui and Lanai) completed 23 clockwise, circular, long-distance 9716 ± 418 SE km foraging trips lasting 18.0 ± 0.9 days. We suggest that low variability in foraging trip distance (cv = 0.17) and duration (cv = 0.19) results from the petrels’ reliance on quartering tail-winds as they circle large anti-cyclones located to the north of Hawaii in the central-eastern North Pacific.