Every summer in southern New Brunswick, thousands of semipalmated sandpipers gather on the beaches in Johnson’s Mills, their only stop on their migration from the Canadian north to South America.

The sight is awe inspiring, with tens of thousands of birds flying in perfect unison.

“It's just very amazing, because you wonder how they just don't bump into each other. They just seem to work as a unit,” says bird watcher Chris Surette.

As the tide rolls in, the sandpipers huddle together on the beaches, drawing in tourists and locals, eager to catch a peek of the small birds.

“It's really beautiful,” says bird watcher Sarah Whitney. “It's like a dance. They all fly very, very close together. It's a bit like a swarm.”

Johnson's Mills is a critical stopping place for the birds on their migration. When they leave the beach, they'll fly 72 hours non-stop to South America.

“This is a critical fueling spot for them,” says Kerry Lee Cormier, of the Nature Conservancy of Canada. “The birds have arrived from their breeding grounds in the sub-arctic and are feasting away on the invertebrates on the flats.”

However, the numbers of birds isn't what it used to be. Now, the beaches at Johnson's mills are under the protection of the Nature Conservancy of Canada. Their goal is to ensure the birds have a safe place to stop during their migration.

“It's really important that people do not go on the beach at high tide because the birds cannot swim and they cannot eat at that time so they need to conserve energy,” says Cormier.

Ninety per cent of the world's semipalmated sandpipers stop on the New Brunswick beaches. Numbers are currently at their peak, with the highest estimate so far at 140,000 earlier this week. The numbers will thin out as the birds gradually start the second leg of their migration south.

With files from CTV Atlantic's Jonathan MacInnis