NEWBURYPORT -- Bill Gette was driving the van down a lonely stretch of Plum Island when he spotted something in the cold, gray sky and reached for the two-way.
''Oh my gosh, Brooke," he squawked excitedly, pulling the van over to the side of the road, ''we have a rough-legged hawk."
''First of the year," murmured someone in the back.
Everyone in the van, and the others in the small convoy, scrambled into action. Telescopes, binoculars, field guides, notebooks, and tripods were grabbed and deftly set up. Through the lenses, the solo hawk soared high over the marshes of the Parker River National Wildlife Refuge as Gette, director of the Joppa Flats Education Center and Wildlife Sanctuary, helped pinpoint the bird's location.
''Very cool." ''Fantastic." ''Wow," they said, hats on, gloves too, against the 42-degree temperature and healthy breeze.
A tundra nester, the raptor was flying over the North Shore, making its autumn migration south from the Canadian subarctic. Like countless seabirds, waterfowl, raptors, shorebirds, waders, and landbirds, the hawk was en route to warmer climes. For some, coastal Massachusetts was the end of the winged journey while others headed to South America for the winter.
Wednesday mornings are for birders at the Massachusetts Audubon Society's Joppa Flats center near the mouth of the Merrimack River. Smack along the Atlantic flyway, the area's mud flats, salt marshes, maritime forests, freshwater ponds, and beaches make ideal habitats for birds looking to rest on their high-mileage flights.
Science, recreation, and camaraderie fuse during the three-hour expeditions (scheduled year round except July) into the adjacent 4,400-acre refuge teaming with wildlife, winged and not. The birders assemble at the center before hitting the road to search the sky.
Opened in April, the education center is their jumping-off place. There, a computer takes a look at birds, complete with photos, birdsongs, and statistics like breeding range and plumage characteristics. A seasonally-adjusted video plays while another computer is the gateway to information about the center's bird banding research program. Children are drawn to the sand table for hands-on experiences with horseshoe crabs and razor clams, and the room next door houses a photo exhibit. Programs and workshops are offered.
Upstairs is the flight deck, an observation area where eagle-eyed observers can sit indoors on stools, protected from the elements, and scan the skies with a guidebook in one hand and a cup of coffee in the other. Outside, you can see upriver to Powwow Hill in Amesbury in the west, Salisbury to the north, and Plum Island's north end to the east. Back inside, plans call for the large magnetic map to have bird locations so that if someone is seeking, say, a snowy owl, they would know where to go.
Birders are quick to share tales. Even before the 10 or so birders hit the vans -- one piloted by Gette, the other by volunteer Brooke Stevens of Cambridge -- Ganson ''Jock" Purcell, a retired Amesbury physician, talked about being on his boat and spotting an adult male common merganser stationed on a log in the river.
''He was trying to make himself one with the log," Purcell said. '' 'You can't see me, I'm part of this log.' "
The convoy drove onto the island, checking out observation points ranging from wooden decks along windswept sandy beaches to the relative comfort of a semi-enclosed blind. Around their necks or mounted to tripods were the tools of the trade, their scopes. Binoculars typically had a magnification range between eight and 10, while the telescopes brought life 20 to 60 times closer.
''Never get caught without your binoculars," said Ben Smith, a retired MIT research engineer from Marblehead. ''You never know."
They tramped along the boardwalk to the beach, quickly setting up. Soon the wind was drowned out by calls of bird sightings and directions.
''One hundred yards to the right!" ''Higher!" ''By the light!" ''Closer to the shore!" To the untrained eye, the waves crashed against the shore and a few dots flittered on the horizon. But through the lens, the landscape came alive with sea ducks and loons. The birds barreled along, they soared, they dived.
In and out of the vans we went, from the beach dunes to the forest where a white-tailed deer watched those watching the birds. Just by the road or via a short walk, the water and sky teemed with specks that became animated through the looking glasses.
''Birding is an identification game, an identification challenge," said former Boston University professor Shane Hunt of Brookline.
The birds can be somewhat still, preening themselves by water's edge, or dart quickly out of sight, a mere blip on the radar. Birding is a group effort. Birds first must be found. Any neophyte can be the first to find one. Then it must be identified with group brainpower. Size, body shape, bill shape, behavior, habitat range, and color all help with identification. On this late October morning, 51 types of birds were spotted. From the majestic flight of a solo hawk to the swarming flocks of dunlins, the birds stopped to feed. Some can double in size, needing fat for the migratory flight.
Like the hawk's, Gette's keen eye spotted a roadside flutter in the brush as he led the treasure hunt.
''I've never seen one on the island before," he said, darting from the van. It was a red-bellied woodpecker. The bird hid. But Gette wanted another look.
So he did some pishing. A sound like a small gushing geyser, pishing tends to attract birds. Indeed, he flushed out the woodpecker and another bird was checked off the list, a rare Plum Island find.
Birding changes perspective. A walk along the beach becomes a hunt. A bike ride becomes an expedition. Or in the case of Stevens, a veteran rower who plies the Charles River, her time on the water provides a chance for bird-spotting. ''I row from April to December and see birds in migration and birds that live on the river," she said.
The morning's highlight came in a life-and-death spectacle in the sky. Flocks of ducks started to leave a pond, a clue that something was going on. Through the binoculars, a peregrine falcon was seen stalking a shorebird. The shorebird's strategy was to climb high in the sky and make a dive.
It did. As quickly as the scene was played out in the sky, the two birds disappeared, as even the lenses couldn't see through the forests and behind the hills. But it was another tale for the birders who flocked to search the sky.
Marty Basch is a New Hampshire-based writer and author of several books.