| Summary: | Several hundred humpback whales, Megaptera novaeangliae, assemble each winter to mate and calve in the nearshore waters adjoining the main islands of Hawaii. Their behavior provides a spectacular display for shore observers and passing boaters. Historical evidence suggests that this population of whales invaded its current Hawaiian habitat only within the last 200 years, and was unknown to the Hawaiians of the pre-European discovery era before 1778. Possible mechanisms for the presumptive recent invasion include dispersion from other areas, accelerated by chronic whaling pressure, and long-term changes in locations of major North Pacific watermasses affecting preferred surface temperature characteristics. A number of short-term local changes in preferred sites within the Hawaiian habitat have apparently occurred in the last 125 years in response to shore-based whaling activities during the midnineteenth century, disturbances to the marine environment during World War II, and offshore effects of the poststatehood construction boom on Oahu after 1959. The major habitat shift and the various local site alterations were seen as adaptive responses of the whales to changes in important physical or psychological characteristics of their assembly areas.
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