PORTLAND, Maine (AP)   The Audubon Society says the 2017 nesting season was the most productive on record for a group of Maine puffins.

Atlantic puffins are small seabirds with an awkward walk and colorful beaks that are popular with eco-tourists. They are at the southern edge of their breeding range in Maine, and the Eastern Egg Rock colony in Muscongus Bay is the subject of much study.

Audubon says the colony increased from 150 to 172 pairs during this year’s nesting season. The society says that is the highest single-year increase since puffins recolonized the little island in 1981.

Atlantic puffins are listed as vulnerable by the International Union for Conservation of Nature. Scientists say they are threatened by warming oceans and changing availability of the small fish they need to survive.