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Ecology & Environmental Sciences - Maine migrants

by Beth Staples | Photography by Holland Haverkamp

sandpiper flock
Semipalmated sandpipers — shorebirds that weigh a whopping 1.4 ounces — give new meaning to the term frequent fliers. During spring and fall migrations, the birds named for the short webs between their toes can rack up around 9,000 miles. After breeding in the Arctic in late spring, the semipalmated sandpipers fly south, resting and refueling for about two weeks in the United States, including in Down East, Maine, before continuing to South America for the winter.

Researchers with the University of Maine and Maine Department of Inland Fisheries and Wildlife (MDIF&W) are in the midst of a two-year study to see if the Maine coast is a welcoming habitat for these feathered friends.

“When in Maine, they’re our responsibility, our birds,” says Lindsay Tudor, an MDIF&W wildlife biologist. “We want to know if the habitat is meeting the birds’ needs.”

Tudor, UMaine wild migratory bird expert Rebecca Holberton and UMaine graduate student Sean Rune are collaborating to find out

Each of the last two summers, they’ve conducted health assessments and placed “nano tags” — tiny VHF radio transmitters — on about 40 semipalmated sandpipers (Calidris pusilla).

Researchers glue the nano tags, which resemble a Tic Tac with a hair-thin, 6-inch-long antenna, to the birds’ back feathers. Each tag emits a specific frequency signal, and comes off during molt.

“They (nano tags) don’t interfere with their natural behavior or ability to gain weight,” says Tudor of the revolutionary technology.

Similar to tourists, sandpipers arrive in Maine in throngs and stay for a couple weeks in July, August or September. They rest on offshore islands and furtively feed on intertidal invertebrates, such as worms and amphipods in the mudflats.

Two VHF telemetry receiver towers erected Down East by the researchers pick up specific signals from each nano tag. By tracking individual sandpiper movements while they’re in the area, the researchers learn more about the amazing birds and how their stay in Maine impacts the rest of their migration.

Data from the watershed project will inform Rune’s graduate thesis. And, similar to data from other bird research projects, it is fed into a repository coordinated by Phil Taylor at Acadia University.

Maine Outdoor Heritage Fund, Eastern Maine Conservation Initiative, Maine Agricultural and Forest Experiment Station and the State Wildlife Grant program of the U.S. Fish & Wildlife Service fund the project that incorporates 50 automated VHF telemetry receiver towers from the Bay of Fundy to Cape Cod, including the two Down East.

“Unless you know the length of stay, you could be double counting (the birds),” says Tudor, a UMaine alumna. “How long do they stay? How much mudflat do they need? How important are the offshore islands? This (data) will improve abundance estimates, determine population trends and conservation efforts.”

sandpiper marsh

Lindsay Tudor is a wildlife biologist with the Maine Department of Inland Fisheries & Wildlife.

In 2013, the study’s first year, Holberton, Tudor and Rune learned that, day and night during the Down East stopover, sandpipers moved between feeding sites along the upper Pleasant and Harrington rivers, and Flat Bay during low tide, and roosted on offshore ledges at high tide.

Hatching-year birds ate and rested an average of 17.5 days in Maine; adults stayed an average of 12.4 days. On average, adult semipalmated sandpipers weighed 5 grams more than hatching-year birds.

The young sandpipers on their first migration may have needed more time to pack on enough weight for the energy reserves required to fly nonstop to their wintering grounds, Holberton says.

Other towers along the East Coast haven’t picked up signals from the migrating birds, which the researchers say indicates that when the sandpipers leave Maine, they fly about 2,400 miles nonstop over the Atlantic Ocean to South America.

Sandpipers can’t tolerate cold water and therefore are unable to land in the ocean to rest, says Tudor, which makes the birds’ stopover on the Maine coast critical to successfully navigating their long, uninterrupted migratory flight.

Tudor says the endurance exhibited by these “little balls of fluff” is one reason among many to be a fan.

New mothers leave the Arctic tundra breeding grounds soon after their chicks are hatched and usually before they can fly. No helicopter parenting there.

The fathers head south soon after, which means the new chicks are left to make the nonstop journey from Addison, Maine, to the coast of South America on their own.

“We expect a lot more from life,” Holberton says. “They make things look simple” — including being able to rapidly nearly double their weight.

Tudor, who previously worked with MDIF&W’s black bear management team, said bears have much of the spring, summer and early fall to pack on weight before they den up. Sandpipers have two or three weeks to add enough ounces so they have enough fat reserves to fuel their continuous three-day or so journey over the Atlantic Ocean.

Another of the sandpipers’ many talents — in addition to making their way back to their exact same wintering site each season — is the ability to break down lipids under the skin to both hydrate and fuel their odyssey over the Atlantic Ocean.

range map for semipalmated sandpiperWhen the semipalmated sandpipers have added sufficient weight, they typically fly 8,000 to 10,000 feet above the Maine coastline, head out over the ocean and catch a good tailwind. It generally takes them two to four days to make the nearly 2,400-mile voyage to the coast of South America.

The researchers say the project demonstrates how much more there is to learn about birds. “You can’t help but be drawn to birds and bird migration,” Rune says. “The more you learn, the more questions that are raised.”

Because semipalmated sandpipers feed on intertidal invertebrates at the interface of land and sea, they’re an indicator species for the health of mudflats and sentinels for the natural world in general, Holberton says.

“The Gulf of Maine ecosystem is really facing challenges,” Holberton says. “We (birds and people) share resources and if birds are in trouble, then so are we. This is another piece of the puzzle.”

Population-wise, the semipalmated sandpipers are in trouble. Despite their amazing abilities, studies indicate that since the 1970s, their numbers have plummeted 80 percent in eastern North America, says Tudor.

The population decline isn’t exclusive to semipalmated sandpipers. Globally, one in eight — more than 1,300 bird species — are threatened with extinction, according to BirdLife International, as reported in National Geographic.

The National Audubon Society’s recently released Birds and Climate Change report indicates 314 species of birds in North America are “on the brink” due to climate change.

For years, birds have been messengers — of changing seasons and new days dawning, says the report. The decline of bird populations is another stark and urgent message, Gary Langham, Audubon’s chief scientist, says in a video. If decisive actions aren’t taken to reduce carbon pollution and protect bird habitats, a host of species could become extinct.

Rebecca Holberton

UMaine migratory bird biologist Rebecca Holberton.

In the Maine-based project, the researchers seek to better understand reasons for the nosedive in numbers of semipalmated sandpipers and the most perilous life stages.

Semipalmated sandpipers face a variety of obstacles, Holberton says, in addition to the effects of climate change in the Arctic where they breed. They also face the loss of coastal habitat due to development along the migration route where they rest and refuel, and they’re targeted by hunters where they winter.

Holberton says sometimes the birds, exhausted from their nonstop three- or four-day flight, will arrive on the coast of South America only to be shot by hunters.

Learning where and why birds are most at peril can precipitate cooperation between agencies and countries, and help policymakers direct resources where they’re most needed.

“It’s really critical to build bridges and span geopolitical barriers,” Holberton says.

MDIF&W reviews permits for shoreland development and makes recommendations for conservation management plans for habitats of high-value to wildlife. Tudor says it’s important to know if these initiatives are working.

Birds have been revered in many cultures around the world for centuries, and are symbols of courage, wisdom, strength, freedom and peace, says Holberton, whose research integrates bird ecology, behavior and physiology.

“I use birds to ask questions,” she says “They’re on every continent. We need to understand the links between habitat quality and availability, and how well sandpipers survive to the next stage.”

Tudor and Holberton are pleased the semipalmated sandpiper project has expanded; this past summer, the U.S. Fish & Wildlife Service con­ducted similar research at the Rachel Carson National Wildlife Refuge in Wells. Comparing the data from Down East with data from southern Maine will be interesting and insightful, says Tudor.

Public interest in and appreciation for birds has helped make the project possible, say the researchers.

Prior to the start of the project, Tudor was aboard a lobster boat searching for prime spots Down East to place the towers. She spied a perfect perch between the Harrington and Mill rivers.

The landowners, including Pat Mudge, were at home enjoying coffee when Tudor motored up and asked if she could put a 30-foot tower on the land. Mudge, a retired newspaper columnist for the Greenwich Time newspaper in Connecticut, readily obliged.

On a nearby bluff, so too did John and Anne Marshall, founders of the Pleasant River Wildlife Foundation, a land trust that works to protect wildlife habitat Down East, including wetlands important to waterfowl, wading birds and shorebirds.

And landowner Frank Taylor welcomed the researchers to use his mudflats to set up nets to catch, do health assessments and tag sandpipers.

Members of the public who take part in Christmas Bird Counts and Project FeederWatch also contribute valuable information about fluctuations in bird populations, Holberton says.

Making Maine a more welcoming place can improve the quality of life and chances for success for all feathered frequent fliers passing through.

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