It is the remains of a glacial moraine. Small hills rise up from the shore at about inland. Knolls and hills are dominated mostly by Red and Scarlet oak trees, which are interspersed with pitch and white pines. On many of the protected bay shores, wetlands and dune ecosystems dominate the land. Sag Harbor Union Free School District includes both the Sag Harbor Elementary School and Pierson Middle-High School. Stella Maris Regional School a Catholic private school, was based in Sag Harbor but closed in 2011. In May 2016, voters in Sag Harbor approved the Sag Harbor Union Free School District's purchase of the Stella Maris Regional School property from the St. Andrew Roman Catholic Church for $3.3 million. Nature preserves have been established in the area and Sag Harbor has rich fauna for its region. Endangered species, such as the eastern tiger salamander, inhabit wetlands surrounding the village. The "Long Pond Greenbelt", which straddles Sag Harbor's southern boundary, is a well-known chain of ponds formed by a retreating glacier. Other natural sites around the village include Barcelona Neck Preserve, Millers Ground Preserve, Sag Harbor Woods Preserve, and the recently acquired Cilli Farm, which lies in the center of the village. Mammals found in these areas include white-tailed deer, red fox, eastern coyote, long-tailed weasel, mink, muskrat, woodchuck, and several bat species. Bottlenose dolphins and harbour porpoises are seen in the bay. There may be river otters, which are close to local extinction in Long Island, but an estimated eight animals are thought to have recently migrated from Connecticut. A large array of amphibian and reptilian species also live in the area, including the marbled salamander, tiger salamander, spotted salamander, box turtle, spotted turtle, gray tree frog, eastern newt, black racer snake, hognose snake and rough green snake, to name a few. Kazimierz Wierzyński, an exiled Polish poet and a writer, who lived in Sag Harbor for almost twenty years with his wife Halina, devoted large parts of his collection of essays "My Private America" to the animals he saw there, especially the birds, and an American "attraction to nature." The Cilli Farm was a dairy farm owned and operated by Vitali and Antonina Cilli and their family in the early 1900s. The village acquired the farm to operate it as a refuge for wildlife in the area.