Field day observer team finds shorebirds declining in Lubec

The rising sun reflects off the Lubec gravel flats tucked between Lubec to the north and Quoddy Head peninsula to the south, stretching a half mile to the east. On August 14, nearly two dozen birders, armed with tripods, cameras, binoculars, spotting scopes and expert guides, came to observe shorebirds as they feed on the flats at low tide during peak fall migration. The event was one of many educational offerings by Cobscook Institute in Trescott.

Shorebirds, like sandpipers and plovers, feed on tiny invertebrates within intertidal mudflats, beaches and wetlands. They are protected by the Migratory Bird Treaty Act of 1918, due to massive overhunting in the 19th and early 20th centuries.

Shorebirds also brought Mark McCollough to Cobscook Bay in 1979 and 1980 during a time when tidal power was being considered. As part of his master's research at the University of Maine, he completed a comprehensive shorebird study for the U.S. Army Corps of Engineers. McCollough is now a wildlife biologist with the U.S. Fish and Wildlife Service.

According to McCollough, at the time people didn't know much about shorebirds, just that they were found in Cobscook Bay. So, in 1979 McCollough, with a spotting scope and a handful of scientific papers, set out to learn everything he could including how many, what species, where they are found, what they feed on, how long they stay, where they go afterwards and how they use Cobscook Bay.

Some of what he learned is shared in his chapter titled "Wind Birds: A Clarion Call for Conservation" in the forthcoming book, Cobscook: Maine's Bay of Boiling Waters edited by Malcolm Hunter and Aram Calhoun, both retired University of Maine professors. In his chapter, he presents his 1980 findings amid the history of bird conservation and population decline.

Shorebirds arrive in Cobscook in early July after nesting in the high Arctic. Through the tagging of 5,000 shorebirds with his colleague Peter Dunn, McCollough found that Cobscook Bay and the Bay of Fundy area were the birds' critical first stop on their fall migration. Their legions were attracted by the cornucopia of intertidal invertebrates present in the expansive mud flats.

In the early 1980s "there were 25,000 to 30,000 shorebirds present daily in outer Cobscook Bay and the Lubec mudflats in July and August." He conservatively estimated that during migration over 100,000 shorebirds came through the area.

On any given day, there were 5,000 semipalmated sandpipers roosting at five locations in the Lubec area alone. Shorebirds roost at high tide just above the high tide line, in small tightly packed groups to rest and digest, after feeding continuously for the previous six to 10 hours. They also raft together on the water.

McCollough found that shorebirds doubled their weight in a two‑week period, consuming vast quantities of intertidal worms and crustaceans on the mudflat during low tide. "When they are here, they are feeding, feeding, feeding, and that fat is the fuel they need to fly two‑days nonstop at 60 miles an hour from Cobscook Bay to their South American wintering grounds," he says, adding, "It is critical to have good quality food and undisturbed roosts to prepare for the arduous journey."

Spotting scopes change the game

The group walked a half mile down the packed cobblestone beach at the high tide line, stopping periodically to aim spotting scopes and binoculars at the mudflat. The backlit view into the rising sun was less than favorable according to some, but most could identify the birds within seconds.

The spotting scope is a game changer. Birders can see fine feathery details, eye‑ring color, even letters on a metal band clamped around a tiny ankle.

A small group of semipalmated plovers with their tiny beaks and black collar come into view as they race on stick‑figure legs, in front of the rising tide. They dart. They zigzag. They probe. Wings akimbo they alight briefly to hop‑scotch over each other down the flat. All are singularly focused on food.

Why the decline?

North American shorebird populations have declined by 37% since the 1970s, "driven by high vulnerability in coastal and wetland habitats," according to the 2019 Science article that found three billion birds are gone since 1970. Unrestricted hunting still occurs in some Central and South American countries. But what caused the Cobscook Bay decline?

McCollough has two possible reasons. First, human disturbance is occurring at the roosting and feeding sites. Dogs, feral cats, ATVs, vehicles or even walking too close can flush birds from their roosts or off the flats and cause them to burn vital calories.

Second, no one knows how or if the ecology of the tidal flats has changed in the last 46 years. Repeating his 1980 study would be one way to find out. "It's important to know if it's still a good feeding area or if pollution, invasive species or something else is making the area less desirable for shorebirds," says McCollough.

One of the most important things people can do, says McCollough, "is give shorebirds some space. If you see a group of shorebirds feeding or roosting, leash your dog so it won't give chase causing them to burn energy or be unable to feed. Walk around them as much as possible so they don't have to fly."

He also referenced increasing signage and fencing and posting roosting areas to encourage people to watch them from a distance using binoculars or a spotting scope. "We can give them a little bit of space to themselves and share the beach with them," McCollough says.

The Lubec gravel bar may be one of the last roosting sites still in use in Cobscook Bay.

A far cry from earlier numbers

Nearing the southern end of the flats, the rising tide pushes the dozen or so birds on the mudflat closer. Hovering over their scopes, the birders view six black-bellied plovers towering over the least sandpipers, the most abundant and smallest shorebird. A peregrine falcon makes a sudden failed charge at a small flock of "peeps" or sandpipers veering and banking in synchrony.

In total, on the three‑hour walk six species of shorebirds are observed for a total of 192 individuals  60 least sandpipers, 50 semipalmated sandpipers, 40 black‑bellied plovers, 25 semipalmated plovers, 12 lesser yellowlegs and 5 short‑billed dowitchers. That's a far cry from the thousands of shorebirds McCollough documented in 1980.

The birders straggle back into the northerly breeze that carries the scent of roses. Although today's survey is but one data point, McCollough can confirm the plummeting numbers. Within half a human lifespan, shorebirds have gone from thousands on any given day in 1980, just at the gravel flats, to barely 200 on one day in 2026.

Finding the silver lining on this "slow day," guide Doug Hitchcox of Maine Audubon voiced a positive thought. "Seeing juvenile birds here is such a good success. That means they had a successful nesting season up in the Arctic, and they're migrating through feeding places like this." He adds, "It is nice to see thousands but also to appreciate what you see."