Next week, when ospreys begin flying back from their winter roosts in the South for their mating, nesting and breeding season on the state's shoreline, their numbers are expected to demonstrate a long-term recovery trend.

Last year, 414 osprey nests were counted statewide by 161 volunteers for Osprey Nation, a new citizen scientist and data collection program started by the Connecticut Audubon Society in partnership with the state Department of Energy and Environmental Protection. Of those, 210 of the nests were confirmed to be active. The volunteers kept data on 174 of the nests, counting the numbers of adults and young, and noting the condition of nesting platforms.

Alex Brash, president of Connecticut Audubon, said the data collected last year shows the state's southeastern corner, from the Connecticut River to the Rhode Island border, is "a hot bed for ospreys."

"The Connecticut River estuary has long been a sanctuary for ospreys," he said. The region, he said, is attractive to osprey because of its less developed shoreline and greater availability of natural coastal areas than the rest of the state. While osprey will travel inland, they mainly nest in shoreline areas, where they hunt the saltwater fish that are the main source of their diets.

Last year, 189 osprey were found east of the Connecticut River, including 75 in Old Lyme, mainly near the Great Island preserve. Two scientists working for Audubon last summer placed telemetry gear on three ospreys there to learn about their habits.

"We learned that while menhaden (a type of shad) in Long Island Sound were their main prey, early in the season the osprey also flew inland seeking stocked trout, alewife and other shad upriver near dams, and even found koi (large goldfish) in outdoor decorative ponds," the society said on its website for Osprey Nation.

The volunteer monitors also counted three of the big birds in East Haddam, 11 in East Lyme, 47 in Groton, 11 in Lyme, 1 in New London, 1 in North Stonington, 33 in Stonington and 7 in Waterford, according to Tom Andersen, director of communications for Connecticut Audubon.

This year, the society is hoping to recruit even more volunteers for Osprey Nation, convinced that with more eyes scanning the marshes and shorelines, even more nests and birds will be found. Brash noted that since the banning of the pesticide DDT in 1972, osprey have rebounded from a low of just 10 pairs in 1970. Their current numbers indicate not only that these raptors are doing well, but also that the fish they depend on are also plentiful enough to support them.

"We've done a lot since the 1970s" by banning certain pesticides, he said. "Some of the worse villains are off the boards."

But ospreys are still vulnerable, and having volunteer observers alert to any changes can indicate new threats both to them and the larger ecosystem.

"The ospreys are a good way to monitor," Brash said.

j.benson@theday.com

Twitter: @BensonJudy

For information about becoming an Osprey Nation volunteer, visit http://bit.ly/1Fk84kl.