FALMOUTH – The number of loon chicks in Maine Audubon’s annual count last summer was the second-lowest in 23 years, the conservation organization said Monday.

Maine Audubon biologists estimate that the loon population in the southern half of the state stands at 2,595 adults and 141 chicks.

The adult count was down 14 percent from 2005, when just more than 3,000 loons were counted. The number of chicks was the second-lowest on record since Maine Audubon began holding its annual loon counts in 1983.

Heavy rains last spring and early summer made for a difficult nesting season, said Susan Gallo, director of Audubon’s Maine Loon Project. It’s possible, she said, that some of the loons delayed their nesting and that the actual number of chicks was higher than the estimate.

“It’s likely that the loon count, which is timed to catch chicks just off the nest in a typical season, happened this year when many birds were still incubating eggs,” Gallo said. “So more chicks may have hatched and survived after the count.”

Maine has New England’s largest loon population but a low chick survival rate compared to neighboring states. Shoreline development, high levels of mercury, lead sinkers and boats all pose problems to breeding loons and their chicks.