Old Lyme — Snatched from certain death in the swift currents of the lower Connecticut River, a three-week-old osprey chick has been successfully adopted into the nest of an adult osprey pair that apparently lost their young in one of the recent powerful thunderstorms that swept through the region.

The chick’s younger sibling, however, didn’t fare so well.

“We’re batting 500,” Paul Spitzer of Old Lyme, an independent ornithologist working for the Connecticut Audubon Society, said Friday evening as he stepped off a small Boston Whaler piloted by Danny Ferrier at the state boat launch at Great Island.

He had just returned from checking on two of the 28 nests built by the large raptors on wooden platforms in the Great Island marshes near the mouth of the Connecticut River.

Peering into the nests first with a mirror attached to a long pole, then from atop a ladder held steady by Ferrier, Spitzer found the larger of the two chicks eating heartily of menhaden bits from the mouths of its attentive adoptive parents.

In a different nearby nest of another pair that had also lost their young, however, he found the smaller chick, probably a week or so younger, had died, even though he had earlier seen the parents through a spotting scope trying their best to feed it.

The life-and-death saga on Great Island Friday night was the culmination of a wildlife drama that began on Tuesday.

Ferrier looked out to the Ragged Rock Creek marshes from his home in Old Saybrook to see a huge log brought in by the river two summers ago suddenly break away from the marsh and start heading into the Connecticut River, carried by a high flood tide.

Three months earlier, a pair of ospreys had built a nest atop the log, and two young chicks had hatched, but were still weeks away from being able to fly when their home began drifting downstream.

“I’ve been watching these babies for weeks,” Ferrier said. “I said, ‘I have to do something.’”

He called town police, then tried a vessel rescue service, but couldn’t find anyone to help. So he decided to get in his Boston Whaler and head out to the log, hoping he could tow it back to shore with the nest.

“I attached it to the boat, but it was too big and the current was too strong, and I started getting pulled out with the current,” he recalled.

Unwilling to give up, he pulled his boat next to the log, took off his shirt and used it to reach over and grab the babies out of the drifting nest.

“I had one foot in the Whaler and one foot on the log,” he said. “I scooped them up and put them in my lap.”

Back on shore, he called the state Department of Energy and Environmental Protection, asking what he should do. DEEP staff suggested he call Grace Krick, vice president of a local raptor education and rescue organization, A Place Called Hope.

He took them to her home in Deep River on Tuesday night, where she fed them bits of striped bass and kept them overnight.

“The babies were so small, the smallest and youngest I’ve ever had,” she said. “But they both seemed healthy and ate well. One of them was considerably bigger and was getting aggressive.”

She contacted Spitzer, who is currently doing a study for Connecticut Audubon on the role of the menhaden population in the growing numbers of osprey nesting in Long Island Sound and the Connecticut River.

As part of that study, he has been regularly visiting the nests in Great Island to check on the success of nesting pairs, so he knew which ones had recently lost chicks. He also knew from previous work that osprey parents would adopt chicks into their nests.

On Wednesday, he, Ferrier and Krick got aboard the Whaler to take the orphaned chicks to the nests where parent had lost their young.

“The babies had perished, but the parents were still hanging around,” Krick said. “He (Spitzer) just climbed right up the ladder with the chicks and put one in each nest.”

Brian Hess, wildlife biologist with DEEP, said the rescue story is further evidence of how osprey, driven to near extinction by pesticide use, have rebounded in recent decades.

“The comeback of osprey is an incredible conservation success story,” he said. “Now, we’re kind of at capacity as far as good nesting sites for the birds.”

With nesting platforms and other premium addresses occupied, pairs are setting up housekeeping in marginal sites like uprooted trees and large logs like the one in Ragged Rock Creek, Hess said. But those sites leave the young more vulnerable to storms and predators, he said.

Working with Connecticut Audubon, DEEP has mapped 450 known osprey nests, “but there are many more we haven’t mapped,” he said.

Spitzer said he loves working with osprey and telling others about the rich marine web in Long Island Sound and the Connecticut River of plankton that feed the menhaden, and the menhaden that in turn feed the osprey, striped bass, bluefish and other “jewels” of the estuary.

He is grateful he could apply his expertise in helping to save one chick, he said, “but Danny Ferrier is the real hero of the story.”

j.benson@theday.com

Twitter: @BensonJudy