One year after a common loon chick in Fall River became the first to be born in southeastern Massachusetts in more than 100 years, conservationists are continuing the slow but steady process of reintroducing a native species to its original habitat. “People do not, right now, even know what a common loon is,” said Ericka Griggs, a researcher at the Biodiversity Research Institute in Portland, Maine. The common loon is listed as a “species of concern” by the state. Griggs estimates there are only about 50 living in Massachusetts, although they used to be plentiful in the area. Beginning in 2015, BRI has introduced several dozen loons from Maine and New York to a pond in Lakeville.