Nantucket's Nesting Terns and Plovers
Nantucket's beaches provide us with a place to escape the heat, swim, fish, or just enjoy the summer sun and ocean breeze. However, the Island's beaches also are home two species of birds - the least tern and piping plover - that depend on this habitat for their continued survival. To these birds, the beach is more than just a nice place to visit - it is the only place where they can nest and raise their young.
Because they are migratory birds, terns and plovers return to Nantucket each spring to face the hazards of nesting on an open beach: ocean storms, high tides, blazing sun, and the lack of shade. These birds are adapted to these harsh but natural conditions and are able to successfully reproduce in this environment. Unfortunately, they have not been able to adapt to the ever-increasing human presence in their shoreline breeding areas. Inadvertent destruction of nests and disturbance by pedestrians, off-road vehicles, and unleashed pets; unnaturally-high numbers of gulls, crows, and other predators; and modification of beach habitat by development activities have all taken their toll on populations of terns and plovers. These birds are now listed as rare and endangered both nationally and within the Commonwealth of Massachusetts. Much can be done to enable these birds to coexist with humans using the beach. Your cooperation is essential in this effort.
Summer 2012 Nesting Shorebird Update
Our Science and Stewardship Department monitors Nantucket's beachfronts annually to protect populations of the rare shorebirds that nest on our beaches and to comply with endangered species regulations. To view the results of our efforts, please click here.
A year in the life of a tern
Terns are members of a family of birds closely related to gulls. They are agile, graceful flyers that hover over the water while searching for small fish just below the surface. When a fish is spotted, the tern takes a dramatic, seemingly reckless dive to make its catch. There are four species of terns that nest in Massachusetts: the least tern, common tern, roseate tern, and Artic tern.
Presently, the least tern (Sterna antillarum) is the only species that regularly nests on Nantucket. Least terns have distinctively pointed wings, forked tail, black cap, and gray and white plumage. They can be readily distinguished from other terns by their yellow bill and legs and small size - about the size of a robin or starling.
Least terns arrive on the island in early May to begin their breeding season. They nest in colonies containing from several to hundreds of pairs of birds on an open, sandy beach. If their breeding efforts have been successful at a particular site, terns often reestablish a colony in the same location year after year. Members of a nesting colony alert each other to potential danger by sounding alarm calls ("kip-kip-kip") and cooperatively dive-bombing and defecating on predators that enter the area. In this way, the members of a breeding colony are collectively more successful than they would be nesting on their own.
The breeding season begins with a period of courtship feeding, where the male catches small fish, brings them to the female, and feeds her. After mating, the female lays one to three small eggs in the nest - a mere scrape in the sand, often lined with shell fragments. Because of their protective coloration, the eggs look just like the sand they are sitting on. They are small oval-shaped, with brown streaks and speckles on a buff-colored background. Both parents share the job of incubating the eggs for approximately three weeks, keeping them warm when the temperature drops at night and protecting them from the intense heat of the sun during the day.
The chicks are helpless and undeveloped when they hatch, and remain in or within the immediate vicinity of the nest for a period of two to three weeks. During this time, they are completely dependent on their parents for food and protection. They are covered by fine, speckled down that gradually develops into buff-colored feathers as they grow. They begin to move around the colony and toward the water's edge at about three weeks of age, where they preen their newly-developed feathers and test their wings. At four to five weeks of age, they are usually flying and learning to fish on their own, although they continue to be fed by their parents.
At the end of the breeding season (mid-to late-August), least terns leave their breeding colonies in family groups. Nantucket serves as an important staging area for least terns that have bred on the island and other tern species, such as common, roseate, black, Sandwich, and Forster's terns, that have bred elsewhere. Thousands of terns can be seen feeding in the harbor and resting and preening on the shoals off Eel Point and Smith Point on the west side of the island, preparing for their long migration southward.
Terns are outstanding migrators. Least terns winter along the east coast of South America - a 3,500 mile round-trip for these delicate little birds. After spending the winter in the south, they return to their breeding grounds in the north to complete their annual life-cycle.
A year in the life of a Piping Plover
Piping plovers are small, sand-colored birds that resemble sandpipers. Their bills and legs are orange and they have a black neck ring and forehead band. They feed along the shoreline and are extremely difficult to see because they blend in so well with the sandy background. Both their scientific name - Charadrius melodus - and common name are derived from their melodious, piping call ("peep-low") that is often heard before the bird can be seen. In 2005, the Atlantic coast population of piping plovers was estimated at approximately 1,400 pairs, compared to the thousands of pairs that once nested along these shores.
Although piping plovers share the beachfront with terns and often nest in close proximity to them, their life cycle is different. Most importantly, piping plovers do not nest in colonies. They nest in single pairs, although these pairs may at times nest within a colony of least terns. They begin their breeding season much earlier, arriving on Nantucket in early April. Male plovers set up and defend nesting territories along the beachfront and attract females through ritualized courtship displays. Their nest is similar to that of least terns - a small hollow in the sand, lined with shell fragments and small pebbles. Piping plovers lay a clutch (set of eggs) of four round, finely-speckled, buff-colored eggs that closely match the coloration of the surrounding beach sand.
If a plover's nest is destroyed before the eggs hatch, the parents will often mate again and lay another clutch - often with less than four eggs. However, these chicks have less of a chance of surviving because they will fledge (learn to fly) late in the season and therefore have less time to test their wings, feed, and prepare for the autumn migration.
The parents incubate the eggs for a period of three to four weeks. Unlike least tern chicks, piping plover chicks are well-developed and immediately mobile (though not capable of flying) when they hatch. Like tern chicks, they are very well camouflaged and virtually disappear against the sandy background when they are not moving. As soon as all the eggs have hatched, the entire family leaves the nest and never returns to it. The parents spend the next four weeks introducing the chicks to their new surroundings. They walk along the shoreline, stopping to feed on insects, marine worms, and tiny crustaceans during the daytime, and spend the nights huddled together in the protective cover of nearby dunes. During this period in their life, piping plovers can roam up to a half mile a day in search of food.
The chicks fledge at approximately four weeks of age. They may remain around their breeding territories or congregate with other plovers on nearby beaches. They leave the area in late August and fly to their wintering grounds along the southern coast of the United States, where they remain until spring migration brings them back north.
Why terns and plovers are rare
Terns and piping plovers were quite common in Massachusetts prior to 1870. However, uncontrolled shooting, hunting, and collecting brought their numbers to a low point at the turn of the century. At that time, terns, plovers, and many other species of shorebirds were indiscriminately harvested as game birds and for their plumes and feathers, used to adorn clothing and millinery. Additionally, eggs were collected from nests and either sold, consumed, or retained by oologists (egg collectors). In 1918, the passage of the Migratory Bird Treaty Act gave these birds federal protection and, as a result, their numbers began to increase again through the 1930's. However, populations have since been steadily declining due to direct and indirect human impacts.
Terns and plovers are protected by state and federal laws
The four species of terns that breed in the Commonwealth (the least, common, roseate, and Artic tern) and the piping plover are listed as "Endangered, Threatened or Species of Special Concern" under Massachusetts Endangered Species Act. Additionally, under the provisions of the Federal Endangered Species Act, the roseate tern is listed as "Endangered" and the piping plover is listed as "Threatened." These designations afford a significant amount of legal protection to these birds.
It is illegal to "take" any listed species. "Take" is defined by the Massachusetts Endangered Species Act as anything done "...to harass, harm, pursue, hunt, shoot, hound, kill, capture, collect, process, disrupt the nesting, breeding, feeding or migratory activity or attempt to engage in any such conduct." Violations are punishable by a fine on not less than $500 and/or imprisonment for up to 90 days.
The Commonwealth's Endangered Species Act and companion Wetlands Protection Act contain provisions for protecting the habitat used by state-listed species for breeding and feeding purposes. Under these regulations, portions of the beach being used or likely to be used by nesting terns and plovers must be closed to vehicular and/or pedestrian traffic if biologists and land managers determine that the presence of humans on the beach will interfere with the bird's breeding success.
For terns, protection of breeding habitat involves fencing off the nesting colony and surrounding buffer zone, since the birds are likely to remain in the general area for most of the breeding season. For plovers, management efforts are considerably more complicated. When the birds are incubating eggs, they can be protected by fencing the area around their nest site. However, they require large areas of undisturbed beach after the chicks have hatched because of their tendency to roam widely during the four to five weeks before they fledge. During this time, it is impossible to anticipate where they may move. When plover chicks sense approaching danger, they instinctively crouch in a nearby depression. Unfortunately, the most common depressions on beaches open to four-wheel driving are the ruts left by these vehicles. Given their small size, protective coloration, and inability to climb out of ruts only a few inches deep, experience has demonstrated that plover chicks can and have been unwittingly run over by even the most attentive drivers.
It is important to keep in mind that shoreline land-owners - both public and private - have a legal responsibility under the Federal and Massachusetts Endangered Species Acts and the Massachusetts Wetlands Protection Act to protect nesting terns and plovers. In many setting, closing off large areas of beach is the only effective way for them to obey these laws, thus avoiding the legal consequences of non-compliance.
Although closing a portion of a beach during the late-spring and summer may be an inconvenience to beach users, these closures have proven to be critical to the survival of these birds when their chicks are flightless and most vulnerable.
You can help protect terns and plovers
The importance of educating beach visitors about terns and plovers, their natural history, and how they can be protected cannot be over-stated. Most of the destruction and disturbance that has been responsible for population declines over the last several decades has been unintentionally caused by beach visitors that were not aware of the presence of the birds or consequences of their actions. The following are some easy steps that you can take to ensure the continued survival of these birds.
Observe and respect posted regulations and beach closures
Repeated disturbances of nesting birds results in their eggs and chicks becoming exposed to extreme temperatures, makes them easy prey, and interferes with the efforts of the adults to feed and care for them. Even the most attentive observer walking through a nesting area can inadvertently step on eggs or chicks because they are so well camouflaged. Birds nesting in closed management areas may not be immediately visible, especially single pairs of piping plovers. Please remember - just because you cannot see the birds does not mean that they are not there.
Pay attention to the behavior of the birds
Birds do not attack humans without reason. If one or more terns are repeatedly diving at you and acting distressed, you are very near their eggs or chicks and are perceived as a threat. Piping plovers often perform a "broken wing display" when an intruder is near their eggs or chicks. The adult bird will crawl around on the sand with its wing extended, making distress calls and feigning injury to attract attention to itself and thus lure the intruder away from the area. If you see any of these behaviors, even if the area is not posted as a nesting area, leave quickly via the water's edge, being careful of where you step. Inform the land manager or property owner of the presence of nesting birds so that they can take appropriate actions to post and protect the area.
Keep your pet on a leash or leave it home
Terns and plovers become very distressed when a dog is near their nesting areas. They identify dogs as predators because of their resemblance to foxes. Dogs are instinctively attracted to nesting areas because the eggs and chicks are easy prey. One dog running through a colony can destroy numerous nests and chicks and distress adults to the point of abandoning their breeding efforts for the year. Every dog - regardless of how well-behaved- must be leashed and under the constant control of its owner when it is anywhere near nesting birds or flightless chicks. Ideally, pets should be left home. High temperatures, as well as lack of shade and fresh drinking water make the beach an unsuitable environment for any animal with a heavy fur coat.
Don't leave litter on the beach
Food scraps, such as the leftovers of a family beach picnic, attract scavengers and predators such as gulls, rats, feral cats, and crows. When the leftovers are gone, these animals will be attracted to nearby tern and plover eggs and chicks.
Don't fly kites or leave fishing line near bird nesting areas
Large objects in the sky, such as kites, disturb nesting birds. From their perspective, kites look like hawks, owls, and other birds of prey. Flying birds can either hit the kite or become entangled in the kite string, causing injury or death. Adults and chicks can similarly become entangled in lines left behind on the beach by kite flyers and fishing enthusiasts.
Thanks to Edie Ray for the use of her photographs.