paragraph: The history of Hawaii reads like the story of a mythical kingdom. The first wave of Polynesian settlers crossed the equator and arrived from the Marquesas in the South Pacific perhaps as early as a.d. These immigrant voyages were breathtaking and treacherous, requiring the crossing of 2,500 miles (4,000 km) of open seas aboard dugout catamarans and outrigger canoes. Their destination was even more resplendent with forests than the paradise we see today, but hoary bats and monk seals were the only mammals in residence. The first Polynesian settlers brought much of what they needed, however, from pigs and chickens to bananas and taro, the root crop that would sustain them. Paddies of taro are to this day a signature crop in rural Hawaii. A second wave of Polynesian immigrants from Tahiti arrived centuries later. By a.d. 1300 they had erased the vestiges of a Marquesan outpost and developed a Hawaiian society of their own. Rival chiefs ruled each island; fish farms and temples were laid out; and tribal and inter-island warfare was common. The chiefs governed their feudal domains by force, ritual, and taboo. The system of taboo (kapu) gave society its laws and the people a complex moral code. To fend off natural and cosmic cata­stro­phes, the rituals of human sacrifice came into play, intended to placate the more violent of the local gods, such as those of the volcanoes and typhoons. While such island societies might seem less than Edenic, the early Hawaiians led a pleasurable life, singing their own histories to the beat of gourds, riding the waves on long wooden surfboards, and developing an elaborate, graceful form of story-dance, the hula. 
question: How did Hawaii's first settlers change the animal population of the islands?
answer: Hawaii's first settlers brought  hoary bats and monk seals