Finally, a Tern for the Better

Looking back at a decade of successful salvation for Maine’s most tenuously surviving shorebirds.

by Sally Stockwell, Ph.D., MA director of conservation
Habitat, Summer 2001

In 1991, the Maine Department of Inland Fisheries and Wildlife adopted what appeared to be outlandish goals for saving piping plovers, an endangered and fast-disappearing species in Maine:

• Population Objective: Increase the number of nesting pairs of piping plovers to at least twenty distributed at all available breeding sites in at least three of the prior five years by 1995.
• Nesting Habitat Objective: Increase the number of active nesting sites to at least seven in at least three of the prior five years by 1995.
• Productivity Objective: Increase the average annual productivity to at least one and a half fledged chicks per nesting female per year at all sites with a statewide average of at least two fledged chicks per nesting female by 1995.

Could we meet the new goals? After a decade of monitoring and managing these endangered shorebirds, the population objective of 20 nesting pairs had been met only once, the habitat objective of seven active nesting sites had never been met and the productivity objective of two chicks per nesting female had been met only twice.

It was a daunting task assigned to the Department by a Citizen's Working Group I was lucky to serve on. As a wildlife biologist for Maine Audubon intimately involved with the day-to-day conservation of these birds, I wasn't sure we could do it. But I knew we had to try. With serious competition from the humans that shared the beach with these birds, I knew it would be difficult.

On my first trip into the field with veteran plover and tern biologist Jane Arbuckle, we skated across the wind-blown sand looking for nesting plovers. Jane kept seeing adults moving across the sand in the distance and small footprints marking the sand at our feet. I saw nothing. How could I see nothing? I had spent years searching for small warblers in the treetops of northern Maine and even more years teaching beginning birders how to find and identify birds on the wing. Yet my eyes were not trained for the sandy expanses before me and the incredibly well camouflaged shorebirds I was responsible for tending. It took me a while, but I did learn to spot them at a distance, cueing in to their quick movements or plaintive peeps. Once they are still and settled into the sand, it can be difficult to see plovers even if you're sure you know where they are. The terns were harder to ignore, as they drifted off their nests, winging through the air and even dive-bombing us if we got too close.

Why should we be so concerned about these little birds? Both least terns and piping plovers are listed as endangered in Maine and threatened nationally. Historical records indicate that piping plovers and their nesting companions, least terns, were probably common summer residents on most Atlantic Coast beaches. In Maine, where once more than 20 miles of sandy beach may have supported more than 200 pairs of plovers and 1,200 pairs of least terns, we now have only 60 pairs of plovers and 60 to 80 pairs of least terns. Still, compared to a century ago, this is a big improvement.

By the beginning of the 20th century, uncontrolled hunting (primarily for the millinery trade) and egg-collecting had greatly reduced the populations of both terns and plovers, and in some areas they were close to disappearing altogether. Market gunners sometimes took as many as 1,200 least terns in a day, shipping their catch to restaurants in Boston and New York. The birds' demise helped ignite a public outcry for their protection. The passage of the Migratory Bird Treaty Act in 1918 protected all migratory birds for the first time, and piping plover and least tern numbers slowly began to recover. However, Maine’s population, and others along the Atlantic Coast, declined dramatically again after World War II as habitat was lost to dune stabilization projects, seawalls, jetties, piers, parking lots and summer home construction. We estimate that more than 70 percent of Maine’s historic plover and tern habitat has been lost.
Piping plovers and least terns need inter-tidal mudflats and tidal rivers for feeding, dune grass for resting and hiding and intact dune systems with frontal dunes and sandy spits for nesting. With only a few such places left along Maine’s coast, and most of these crowded by summer residents and visitors, tern and plover populations will likely never return to historical levels, but their populations can and are still rebounding from the destruction of the early 1900s.

When Maine Audubon first began surveying for least terns and piping plovers 20 years ago, we had no idea how many birds were still nesting along Maine’s coast. The results were not encouraging. Soon thereafter both species were listed as endangered. In 1977, the first year of surveys for least terns, between 50 and 60 pairs nested and raised 50 young. In 1981, the first year of surveys for piping plovers, only 10 pairs of plovers nested, and raised only nine young.

Over the next decade, with the cooperation of a handful of landowners, Maine Audubon erected stake-and-twine fences around active nests to reduce the loss of eggs and chicks to predators. Great effort was taken to locate and monitor these nests and to keep people and pets away from them. Metal fencing was sometimes used around colonies to try to keep foxes out. But even with these efforts, recovery was slow—too slow. Foxes climbed over the fences and skunks dug under them. Black-backed gulls invaded the colonies from above and carried away eggs and chicks, and occasionally even adults.

We had to come up with a new approach if we ever hoped to see numbers significantly improve. After a decade of actively monitoring and managing these birds, we had increased the plover population from 10 pairs to 17, and seen the number of least tern pairs fluctuate between 39 and 131, with sometimes abysmal nesting success. What else could we do?

In 1989 we introduced a new technique that initiated a significant turnaround for the plovers. Once piping plovers return to their Maine breeding grounds, Maine Audubon staff and volunteers visit each site. When the pairs begin to nest, each nest is surrounded with a circle of wire-mesh fencing, called an exclosure. The openings in the mesh are large enough to allow birds to easily walk through but small enough to prevent predators from getting in. Rows of twine placed over the top of the exclosure keep avian predators from swooping down on the nest. Studies in Maine and elsewhere show that these exclosures greatly increase the likelihood that piping plover eggs will hatch. Using these exclosures meant we were able to not only meet but exceed the recovery goals and objectives set for piping plovers in 1991.

In fact, during the last five years (1996–2000) we have had between 47 and 60 pairs of piping plovers nesting on as many as 19 different beaches. Productivity has dropped slightly, from two chicks per pair during 1991–1995 to between one and a half to two chicks per pair since then. At some of these sites, the birds are attempting to adapt to less-than-ideal conditions, including nesting in cobble or rocks instead of sand, in front of seawalls and among high densities of people or pets. But with the help of intensive management and landowner cooperation, some of these nests have fledged young despite these disadvantages. We are hopeful that the population will continue to grow, occupying more of their historic habitat.

The terns have posed a more perplexing problem. During the past decade, efforts to protect least terns by restricting access to their nests and controlling predators have met with variable success, with a high of 126 pairs producing 81 fledglings in 2000 to a low of 90 pairs producing only eight fledglings in 1989. Because least terns nest in large colonies, it is difficult, costly and ineffective to erect exclosures around their nests; moreover, past attempts have simply not stopped predators. But in 1999 and 2000, with funding from the Maine Outdoor Heritage Fund, Maine Audubon stationed night-owl biologists at the largest colony of least terns to ward away wily foxes and other predators that may try to sneak into the colony while the birds are sleeping. It proved highly successful, with 67 young produced from only 62 pairs in 1999—the highest productivity we’ve seen since the start of monitoring in 1977 (with the exception of 1992). The technique was adapted from similar work done on offshore islands to ward away predators from colonies of common, Arctic and roseate terns. Biologists working with terns in other states along the Atlantic listened enthusiastically to Jones’ description of the technique at a meeting in Virginia last fall. At last, they exclaimed, there is hope for least terns!

Today, a Maine Audubon-led coalition of conservation organizations and individuals is working with local residents, landowners, real estate brokers and the general public to conserve these endangered shorebirds. Coalition members include the Maine Department of Inland Fisheries and Wildlife, The Nature Conservancy, the U.S. Fish and Wildlife Service, the Maine Bureau of Parks and Lands, the Wells Reserve, Bates College, the Small Point Beach Association, the Prouts Neck Country Club and the Kennebunkport Conservation Trust, plus various municipalities and dozens of volunteers. In addition to advances in fencing techniques and predator control, much of the success of our program results from an expanded partnership, solid landowner relations and management agreements developed with several coastal towns.

The dramatic increase we have observed in piping plover numbers in Maine during the past eight years would be impossible without the generous support of individual landowners. Most landowners from whom we request permission to manage their beaches have agreed to allow at least some type of monitoring or management. During 2000 alone, we worked with more than 94 private landowners to protect plovers on their beaches.

York County landowners, such as Don and Bonnie Currie, resisted giving their beach up for the birds at first, particularly when Audubon interfered with their plans for building a house on a frontal dune, but later embraced the birds’ protection with as much, if not more, passion than our own biologists.

In a letter of support for the re-authorization of the Endangered Species Act written to U.S. Representative Gerald Studds (D-Massachusetts) in 1993, the Curries wrote: “Thanks to the Audubon team, now we can pass down another significant value to our children and grandchildren. They now have an opportunity to share in a positive relationship with caring professionals and to play an active role in the preservation of an endangered species. Both our home and our lives have been enriched by our involvement with the Audubon team.”

The Curries have not only allowed us to monitor and manage the birds on their beach for more than a decade, but they have invited us to use their driveway and park vehicles at their house, have monitored the birds themselves and alerted us to the need for fencing around a plover nest or for removal of an errant skunk. In addition, they helped us negotiate the purchase of a spectacular undeveloped beach adjacent to their property to be included in the Rachel Carson National Wildlife Refuge and managed specifically for the terns and plovers. Depending on the extent of winter storms, the beach now harbors anywhere from three to five pairs of piping plover and twenty to forty pairs of least terns annually. It is one of our most productive sites.

Volunteers add another essential element to this project. Much of what we accomplish is a direct result of their efforts. Each year, Steve Emmons graciously stores our growing supply of fencing in his barn and helps to manage Goose Rocks Beach. Joan Junker and Gene Gray walk Goose Rocks Beach daily and report any new sightings of adults, nests or chicks. In 1999 and 2000, 28 volunteers in the Wells area attended a training session, were given volunteer monitoring handbooks and, subsequently, spent many mornings and afternoons surveying Wells Beach, hoping to reduce conflicts between birds and people. Real estate brokers and agents distribute packets of information to their clients asking renters to Share The Beach With an Endangered Species.

Working with landowners and volunteers in Maine is one of the most satisfying aspects of our recovery program. Together, we met and exceeded the last set of goals. Jody Jones, who has spearheaded the recovery project for Maine Audubon during the past decade, says, “And we can still do more. We are constantly experimenting with new techniques for managing the plovers and terns. This year, we are using blueberry meshing instead of twine over some exclosures, which should do a better job of keeping out small avian predators such as crows and ravens. Also we have trained a new set of volunteers to monitor plovers on Ogunquit Beach, and are using “spotters” to walk in front of the beach-cleaning machines to insure no nests will be run over. We’re hopeful that with continued vigilance and new ideas, we can secure a healthy population of both least terns and piping plovers in Maine.”

In fact, new recovery goals and objectives are about to be developed for both piping plovers and least terns this year, under the guidance of the Maine Department of Inland Fisheries and Wildlife. Jody Jones will serve on the committee. How bold shall we be this time? Let’s hope our future work will result in more landowners writing, as Ginny Almeder did in April of 1999: “I hope we have a nesting pair in front of our house again. It is wonderful to be able to look out the window and see the nesting activity. It is a privilege to share the beach with such wonderful creatures.”

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Getting to know piping plovers and least terns

Piping plovers are small shorebirds, about seven inches long, marked by a white underbelly, a beige back the color of sun-bleached sand, a white rump, a black upper tail with a white edge, and, most notably, a single black breast band. Males return to Maine in early April to establish a territory. You may see male plovers chasing other males out of their territory, conducting an aerial display, stamping their feet and puffing out their feathers to look bigger as part of their territorial displays. Females arrive soon after the males and choose a mate. Once the pair has formed, four eggs are laid in a shallow scrape in the sand and incubated for about twenty-eight days. Chicks leave the nest within a few hours of hatching and begin feeding themselves under the supervision of their parents. Plovers feed in the inter-tidal area and around seaweed that has washed up looking for marine worms, fly larvae, crustaceans and mollusks. The chicks are very well camouflaged and will often crouch down in a depression and freeze as a way to avoid detection. During this time they are very susceptible to being chased by dogs, being carried off by black-backed gulls, or being crushed unwittingly by a heavy foot. If all goes well, after about twenty-five to thirty-five days the chicks are ready to fly, and they begin separating from their parents more and more. Adults usually leave for their wintering grounds—along the Atlantic coast from North Carolina to Mexico and into the Bahamas and West Indies in late August—several weeks before the young.

Piping plovers often share their nesting sites with the colonially nesting least tern, which is the smallest of our terns in Maine and the only one of four species to nest on the mainland. The least tern has a gray back, white chest and belly, orange legs, and the black head characteristic of the tern family. At only nine inches in height, this tern is easily distinguished from others by its white wedge on the forehead. Least terns winter in Brazil, and return to Maine each May to begin their courtship rituals. They lay two to three eggs in a small sandy depression and incubate the eggs for approximately twenty-one days. After hatching, the chicks are completely dependent on their parents for small fish until they are old enough to fly and feed on their own. They usually stay in or near their nest during this time, and the adults protect the nest by dive-bombing any would-be predators, including black-backed gulls, owls, kites, green-backed herons, foxes, dogs, and even wildlife biologists.