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Buzzards Bay Tern Restoration Project
Venture
into the waters of Buzzards Bay, Massachusetts in the spring and summer
and you may well be treated to the sight of agile, graceful terns darting
above and plunging into the sea. The species you are most likely to
see are the Roseate Tern, Sterna dougallii, and the Common Tern,
Sterna hirundo. These migratory birds arrive in Massachusetts
in April and May to nest, mostly on islands, and depart again for their
wintering grounds (as far south as Argentina) in August and September.
Their primary foods are juvenile fish such as herring, sand lance, and
mummichog. Both tern species are long-lived, with the oldest wild birds
reaching their mid- to upper-20s. More detail on these species can be
found on our fact
sheets.
Colony Life:
Common and Roseate Terns are colonial nesters. A major benefit of nesting in a colony is group defense against intruders and predators. While Common Terns will nest in single-species colonies, Roseates will not. In this part of the world, Roseates always nest with Common Terns, which vigorously defend their nests and young against intruders -- benefiting the much more timid Roseates. This defense is necessary because eggs and young, although camouflaged with surroundings, are still vulnerable to being gobbled up by a predator or stepped on by a clumsy or inattentive human. Eggs are laid directly on the ground and chicks are "earth-bound" for about three or four weeks until they can fly (Figure 1).
Figure 1. Common Tern chicks and egg, Penikese Island, MA.
A visit to a large colony of Common and Roseate Terns is not easily forgotten. Intruders are mobbed by clouds of shrieking, divebombing, defecating terns. Humans (and some other animals) may also be pecked on the head and any exposed skin mercilessly by Common Terns. You would emerge spattered and weary, but hopefully with added respect for these tenacious birds.
Because these birds are so highly vulnerable, all tern colonies in Massachusetts are off-limits during the nesting season. Colonies may only be entered for approved research or management purposes. However, they can be enjoyed (much more peacefully) from a distance through binoculars or spotting scopes. You can also watch terns on our real-time Bird Island tern web camera. The camera is active from approximately mid-May through mid-July.
History:
Until the 1880s, Common and Roseate Terns were abundant in Massachusetts, with hundreds of thousands of pairs reportedly nesting at Muskeget Island (off Nantucket) alone. (See Nisbet, I.C.T. 1973. Terns in Massachusetts: recent numbers and historical changes. Bird-banding 44: 27-55.). Like many other bird species, however, terns were victims of their own loveliness. They were hunted nearly to extinction along the Atlantic Coast for their plumes, which were used to adorn hats. In Massachusetts, large numbers of terns survived at just a few locations.
The conservation movement swelled during that time period -- in great part due to outrage over the hunting of birds for their feathers. Consequently, both local and national legislation was enacted that provided legal protection for many birds. In Massachusetts, as in other places, terns responded to enhanced protection and populations partially recovered.
Starting in the 1930s, gulls (especially Great Black-backed and Herring Gulls) gained a footing in the Commonwealth and their populations exploded, aided by food from garbage dumps and discards from the fishing industry. Gulls overtook Common and Roseate Terns' preferred nesting sites -- the offshore islands that are relatively secure from predators -- and tern populations plummeted. Gull populations continued to grow through at least the 1970s. Closure of dumps and better management of fisheries waste have probably been major factors that checked the growth of gull populations; gull populations have declined substantially since their peak.
Current Status:
Tern populations are still struggling, although progress has been made for some species. The Roseate Tern is listed as Endangered pursuant to the U.S. and Massachusetts Endangered Species Acts. The Roseate was listed principally because of the contraction of its breeding range, with many breeding sites lost (especially to gulls) and not recovered, and secondarily because of declining numbers. The Common Tern and two other species that nest in the Commonwealth -- the Least Tern, Sterna antillarum, and the Arctic Tern, Sterna paradisaea -- are state-listed as Special Concern.
In Massachusetts, most of the major nesting islands for Common and
Roseate Terns are in Buzzards Bay at Bird, Ram, and Penikese Islands
(Figure 2). Another key site is Monomoy
National Wildlife Refuge off Cape Cod, which supports the largest
Common Tern colony on the Atlantic coast. Common Terns have increased
fairly steadily in the Commonwealth since the mid-1980s, although growth
has slowed in recent years (Figure 3). After nearly two decades of relatively
steady growth, the Roseate Tern population is in decline, both in Massachusetts
and in the Northeast as a whole (Figure 4), for unknown reasons.
Figure 2. Locations and sizes (in hectares) of the major tern nesting
islands in Buzzards Bay, MA.
Figure 3. Number of pairs of Common Terns in Massachusetts,
1985-2009.
Figure 4. Number of pairs of Roseate Terns in the Northeast
U.S.
and Massachusetts, 1988-2010.
Terns are highly vulnerable to threats such as human disturbance, habitat
loss, predation, oil spills, and competition with gulls. In a given
year, Common Terns usually nest at about 35 sites statewide, and Roseates
at five sites. The birds, however, are highly aggregated, which greatly
increases their vulnerability to threats. About 95% of Common Terns
are clustered into just six sites (Figure 5). The situation for Roseates
is even more serious: 95% are concentrated at just two sites (Figure
6).
Figure 5. Number of pairs of Common Terns at
nesting colonies in Massachusetts, 2009.
Figure 6. Number of pairs of Roseate Terns at
nesting colonies in Massachusetts, 2010.
Buzzards Bay Tern Restoration Project:
The communities surrounding Buzzards Bay have a deep-rooted, sea-based heritage of which terns are a part. Terns benefit these communities and visitors to the area aesthetically, culturally and economically. The sights and sounds of summer seabirds greatly enrich the marine environment. Terns benefit fisherman directly because the presence of a flock of terns often signals the presence of commercially and recreationally important fish: large, predatory fish force smaller "forage" fish to the surface, where they are accessible to terns.
Through the early 1950s, up to 15,000 pairs of terns nested on four to five islands and fed throughout Buzzards Bay. By 1975 only 1,400 pairs remained, all at Bird Island. In addition to being displaced by gulls, terns were injured by exposure to PCBs from New Bedford Harbor, a Superfund site.
Intensive management at Bird Island (Marion) since the
late-1960s, at Ram Island (Mattapoisett) since 1990 and at Penikese
Island (Gosnold; one of the Elizabeth Islands) since 1998 has resulted
in a gradual recovery of numbers to nearly 8,000 nesting pairs as of
the 2010 nesting season (Figures 7 and 8). Funding to restore terns
to the New Bedford Harbor environment has been provided by the New
Bedford Harbor Trustee Council from 1999 to present. Management
at Bird Island is conducted with the cooperation of the Town of Marion.
Figure 7. Numbers of pairs of Common Terns at Bird, Ram,
and Penikese Islands, Buzzards Bay, MA, 1970-2010.
Figure 8. Numbers of pairs of Roseate Terns at Bird, Ram,
and Penikese Islands, Buzzards Bay, MA, 1970-2010.
Because of terns' vulnerability to threats, populations in Buzzards
Bay are managed aggressively in order to protect the improvements already
achieved and extend restoration (Figure 9). Together, Bird, Ram, and
Penikese Islands support nearly half the Roseate Terns in the endangered
Northeast population (Figure 10). Therefore, protection and management
of the terns and the islands is of critical importance. Each year, MassWildlife
staff protects, manages, and monitors the terns on these islands to
increase abundance, enhance productivity, and gauge progress towards
recovery of the populations. Seasonal tern restoration job opportunities
with MassWildlife's Natural Heritage & Endangered Species Program
are available annually.
Figure 9. Tern research at Penikese Island, MA.
Figure 10. Number of pairs of Roseate Terns at major
nesting colonies in the Northeast U.S.,
2010.
Projects to restore nesting habitat -- rapidly dwindling due to erosion and sea-level rise -- are underway at tiny Bird and Ram Islands (Fig. 11), which lie just a few feet above sea-level. At both sites, eroded areas will be filled with sand and gravel to create suitable tern nesting habitat. At Bird Island, a deteriorating seawall will be rebuilt to better protect the upland habitat.
Figure 11. Tern nesting habitat restoration on Ram Island: (A) March 2010, before construction, and (B) July 2010, post-construction.
For more information about terns or the Buzzards Bay Tern Restoration project, contact Carolyn Mostello at Carolyn.mostello@state.ma.us.