Pre-dawn on the Connecticut River.

A silvery crescent moon shimmers in an onyx sky. Silence, save for rustling leaves along shore and the soft splash of kayak paddles. Wisps of mist sweep over gentle ripples.

“Bit of a chill,” I say to my son Tom while cinching a spray skirt — less to ward off water and more to trap my body heat in the cockpit.

Cloaked in darkness, we glide north toward Goose Island in Old Lyme’s Lord Cove.

For the past six years, I’ve made this pilgrimage at sunset in late summer/early autumn to observe one of nature’s most astonishing phenomena: hundreds of thousands of migrating tree swallows swooping and swirling before landing on the 75-acre island.

This year, I decide to watch the avian aeronautics, called a murmuration, in reverse — tiny birds taking off en masse at daybreak to hunt bugs before returning later in the evening to hunker down among Goose Island’s phragmites.

To kill time before sunrise, Tom and I circumnavigate the island, and I check my watch.

“Any minute,” I announce.

A lone osprey soars, followed by a great blue heron, gulls and ducks. Cormorants perch on pilings, while a pair of swans commandeer a clump of rocks at high tide.

Suddenly, Tom blurts, “Look!”

A small cluster of swallows, maybe a few dozen, rises above the reeds, as ephemeral as a puff of smoke. The main murmuration should follow momentarily, I hope.

So we wait. And wait. And wait. Neither a peep nor a flutter.

“That’s it?” Tom asks.

I shrug my shoulders and joke, “Total waste of time.”

In truth, it has been a wonderfully serene morning — but still, I feel a little cheated.

So I make plans to revisit Goose Island a few days later with four friends: Laura and Chris Stetler; and Tim and Sheri Lambert. The heck with getting up at 5 a.m. — we decide to meet at the launch in late afternoon.

I enticed these same friends last year for what I promised would be a stunning, life-changing experience. I was left with egg on my face when only a handful of swallows showed up.

One thing I’ve learned: You can’t rely on the tiny birds.

Though everybody insists they had a wonderful time last year, Chris offhandedly mentions that he managed to see only two swallows.

“Don’t worry,” I proclaim. “Tonight is going to be epic.”

The reason for my optimism: While carrying my kayak to the water, Dick Shriver, whose riverfront home at the end of Pilgrim Landing Road overlooks Goose Island, comes over to chat. A lively, active 87-year-old, Dick paddles out to see the swallows about a dozen times a year and keeps an unofficial tally of the turnout.

“Five-hundred-thousand the other night!” he crows.

Dick, publisher of a new magazine, Estuary, which focuses on the Connecticut River, tells me that the birds are drawn to Goose Island because its phragmites have been spared.

Elsewhere throughout the lower Connecticut River shore, the highly invasive plants have been cut down, dug up and sprayed with herbicides, but in deference to swallows, wildlife officials have allowed the fast-spreading reeds, which serve as cover from hawks, falcons and other winged predators, to take over the tiny island.

Twelve-foot-tall stalks are swaying in the breeze when our crew approaches in late afternoon. We drift in an ebbing tide and watch the sun dip below the western shoreline across the river.

Then: Flit … flit … flit …

Swallows are zipping toward Goose Island from every direction. We gaze up, and suddenly a vast cloud of birds fills the sky. For more than half an hour, they circle, soar and dive, before forming a tornadic vortex that seems to suck them to Earth.

We are too overwhelmed to utter words other than “Wow!” and “Fantastic!”

After a few minutes, though, Chris has recovered his power of speech.

“Well, that’s 499,998 more sparrows than we saw last year,” he says.

Eager to press my luck, I invite Maggie Jones and her son, Clancy Philbrick, to join me a few nights later. Maggie, director emeritus of the Denison Pequotsepos Nature Center in Mystic, has for more than a decade led groups to Goose Island for what she calls an “immersive, multi-sensory experience, inspiring and mysterious … a visual kaleidoscope.”

Many bird species swarm during migrations, but none in such vast numbers, or with such panache, as swallows, en route from the north to the southern United States, Mexico and Central America.

“All swallows are incredible flyers, spending more time in the air than most other birds — they eat, drink and even bathe on the wing,” she notes.

Maggie explains that unlike other swallows that only eat insects, tree swallows can digest the fat in bayberry (Myrica pennsylvanica), an important fuel, especially if they fly through a cold snap on their journey south. They also sometimes feed on the beach or marsh edge, eating tiny crustaceans, spiders and seeds. This gives them a little more flexibility than other insectivores in unpredictable weather conditions.

It is the last full day of summer, and we are part of a small fleet of kayaks, canoes and paddleboards out to see the show. A gusty north wind has settled down — almost showtime.

At last, the winged stars arrive to cheers from our floating audience. Moments later, a hush falls over the crowd as the swallows form intricate mosaic patterns against a crimson sky, then break into a trio of separate flocks — a three-ring circus directly overhead.

Darkness descends like a curtain, and soon it is raining swallows. One flock plunges in a wide column while a second drops to Earth in stages, leaving a final cluster to continue their aerial stunts before descending in a corkscrewing dive.

Clancy is gobsmacked, and even Maggie, who has witnessed so many murmurations over the years, is starry-eyed.

“It’s always amazing. Never the same twice,” she says.

If you want to take a chance of seeing sparrows, they should stick around for another week or two; get to the launch on Pilgrim Landing Road off Route 156 by late afternoon to secure a space in the small, unpaved parking lot.

Lord Cove, just north of the launch, is more protected against wind and powerboat wakes than the main river west of the island.

Enjoy the show (if the swallows cooperate).