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Description:An attractive, medium-sized, black, white, and gray waterbird, 12 to 15 inches in length, the Common Tern is the most widespread tern in North America. It has a smooth, round head with a black cap, red legs, a narrow pointed beak, and a deeply forked, white tail. The plumage is pale on the underside and darkens on top with wear, with black tips on the wings, some specimens taking three years to reach full plumage.
The diet of the Common Tern consists primarily of small fish, but it may also eat shrimp and aquatic insects, which it catches by diving directly into the water, or by skimming the surface. Similarly, it drinks water while flying, gliding over the water and dipping its beak repeatedly into the surface. Common terns living near oceans will drink the saltwater, even if freshwater is nearby. Like many shorebirds, they have nasal glands which excrete any excess salt.
Life History:After partaking in courtship rituals that include acrobatic flights and courtship feeding, monogamous pairs of the Common Tern lay from one to four eggs on a nest of dead vegetation on the ground above the high tide line. Incubation lasts from 21 to 27 days and the eggs are attended by both parents. Around 28 days later the young fledge, but they are still dependent on their parents as it takes them another three to four weeks to develop the skills to proficiently hunt for themselves. Generally they lay only one clutch a season but they may attempt a second if the first was unsuccessful. Young terns begin breeding at about two or three years of age.
Habitat:The Common Tern prefers sand and shell beaches, rocky inland shores, and grassy uplands along oceans, lakes, and rivers. Breeding grounds range along the Atlantic Coast from Canada down to South Carolina during mid-April to mid-October. It migrates as far as its southern-most breeding grounds in the southeast U.S. to South America and the Islands each winter. During breeding season terns may gather in large colonies, where a group of terns is called a committee. Some birds return to the exact same spot, with the same partner, year after year. Although many group together they will vigorously defend their nesting sites and may defend their feeding territory as well.
Status:Population numbers of the Common Tern dropped sharply at the beginning of the last century due to the millinery trade, as their feathers were a popular decoration for ladies hats. After some recovery in the 1920's and 1930's, numbers dropped again during the 1970's, this time credited to the prevalent use of pesticides, competition for nesting sites and increased predation, and habitat disturbance by humans. Although not federally listed, they are considered a species of special concern in all states in the Northeast Information Node and the states surrounding the Great Lakes, with status ranging from endangered in Vermont, to threatened in New York, to special concern in Massachusetts.
The Common Tern is listed in all Action Plans for the eight states of the region.
TAXONOMY:
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Ciconiiformes
Family: Laridae
Genus: Sterna
Species: hirundo
"Birds are indicators of the environment. If they are in trouble, we know we'll soon be in trouble."
~Roger Tory Peterson
Invaluable species
Birds are a valuable resource of the American people in many ways - economically, scientifically, culturally and aesthetically. The Northeast region alone is home to more than 500 species of birds. Birds are found in virtually all habitats in the United States, and in many ecosystems function as key indicator species For example, raptors (birds of prey who hunt primarily on the wing), are generally found at the top of the food chain. Not only are songbirds beautiful to look at and listen to but they are very beneficial to their surrounding environments; in agricultural areas, some songbirds may eat up to 300 insects a day, which if left unchecked could damage crops and surrounding trees.
Common characteristics
Birds have several characteristics specific to their class. While many of these characteristics can vary from species to species, it is their combination that sets birds apart from other animals.
Feathers are a defining characteristic of birds. All birds have feathers, and all animals with feathers are birds.Feathers evolved from scales and now serve a variety of purposes: they assist in flight, determine the appearance of the species, and help regulate body temperature (birds are endothermic, or warm-blooded; they, generate their own heat independent of ambient temperature . ) There are many different types of feathers on one bird and feathers are replaced at regular intervals in a process called moulting. The color of the feathers comes from a couple different sources. Some colors come from the colored pigments found in the keratin of the feather while other colors come from the way the feather selectively reflects light. Some blue and green feathers appear that way only because those are the only wavelengths of color reflected by the feather, giving it an iridescent appearance. Displaying feathers and plumage can be used as communication for many bird species, such as courtship dances or mere danger signals.
Birds have several features that allow them to fly. While all birds in the Northeast have wings and can fly, wings themselves are not the only characteristic needed for flight. Birds have an array of unusual adaptations which enable them to take wing. The skeletal structure is light, yet very strong. It is actually connected directly to the respiratory system through a series of hollow cavities in the bones and air sacs connected to the lungs. Muscular contractions of the ribcage force air in and out of various sacs and supply a constant supply of fresh air to the lungs.
The rest of the skeletal structure is also highly developed. The support of the main appendages lay close to the center of the body to improve balance at all times: while walking on the ground, perched in trees, or flying in the air. The sternum has developed a large keel to firmly support the breast and wing muscles. The strong legs have evolved to support the stress of landing and taking off, while the feet vary from species to species to suit a variety of needs. The webbed feet of ducks help them propel through the water, the strong toes of the eagle pluck and kill prey in the air, and the effective feet of woodpeckers holds them fast to the vertical tree trunks while they hunt for prey.
Birds lack teeth and cannot chew their food. Instead birds have bills, and most have tongues, each developed to suit the needs of the species. For this reason, bills can be a good indicator of the species’ feeding habits. To compensate for the lack of teeth birds have a gizzard which helps them break down food before passing it along to the intestines.
All birds lay hard-shelled eggs. Some eggs have very thin shells while others can be quite thick. Some hatchlings, like geese, are fully formed and ready to leave the nest immediately; while others, like robins, require a bit more development before they are ready to face the world. Most species in the region devote a good deal of time to brooding the nest and then raising the offspring after the eggs have hatched.
Birds can make a variety of calls, and some species can recognize the calls of their own species more precisely than humans can. Birds have a highly developed sense of hearing. Different sounds can distinguish and define different relationships, such as mother to child, or mating pairs. Some birds, such as owls, have developed an even more sensitive form of hearing called binocular hearing which enables them to locate and hunt prey in the dark. The hearing mechanisms of birds are all located completely within the skull, and like mammals, can also assist with balance.
Other common characteristics of birds include a four-chambered heart and very efficient circulatory system, acute eyesight which can even see ultraviolet colors, a specialized third eyelid, and a highly developed sense of touch. Birds in the region generally have a very poor sense of smell.
Daily threats
The Northeast region is the most densely human populated region in the United States, with many urban environments. These urban areas can pose unique threats for many species, particularly birds.
The main day to day threats birds face include collisions with buildings, power lines, and cars; poisoning, by pesticides and oil spills; predation, by cats both feral and domestic; and the danger of being caught, particularly for seabirds caught in commercial fishing gear. It is the combination of all of these risks that leave scientists concerned about bird populations.
Raptors, being at the top of the food chain, may face greater threats than the other bird species, as risks from pesticides and poisonings become concentrated as levels of the toxins increase up the food chain, in a process called bio-magnification.
Still, habitat loss is by far the biggest threat to all bird species. In the past 100 years, freshwater wetlands have decreased by 50%. Natural forests have become reduced and fragmented as human populations grow and spread leading to alteration and loss of habitat. This urban development will continue but human-wildlife interaction can be improved to reduce avian mortality.
Small steps in the right direction
The conservation of bird species is not just a regional issue, because many birds in the Northeast are migratory. They may use different locations for wintering, breeding, and feeding, extending as far down as South America. Some of them may travel for hundreds and even thousands of miles every year to reach far off destinations, using many stopover points along the way. Habitat loss in any of these locations could have disastrous effects and risk the continued survival of the species. Many of these migration paths occur along areas where large human populations have developed. In these areas, simple actions to help reduce fatal bird collisions, such as offering education and awareness programs about birds, or requesting that tall buildings dim or turn off lights at night during peak migration, may help migrating bird populations. But joint collaborations between many regions appear necessary to help protect the diverse habitats these species occupy.
There are small things that anyone can do to positively impact conservation of bird populations, for example, buying products produced in an environmentally-conscientious way, such as shade-grown coffee. Some coffee plantations purposely grow their coffee under the shade of trees, either natural forest or planted. These trees not only help protect the crop and soil, but provide habitat for birds and other animals in the area. The biodiversity found in these coffee plantations is second only to the biodiversity found in undisturbed forests.
For more information, contact your local Audubon Society or go to:
Partners in Flight
Description:The Piping Plover is a small, stocky, sandy-colored bird resembling a sandpiper that lives on the beaches along the Atlantic Ocean. Fully grown it will reach approximately seven to eight inches in height. The adult has a short and stout bill, yellow-orange legs, a black band across the forehead from eye to eye, and a black ring around the base of its neck. Males are often a bit brighter in their coloring than females. The Piping Plover runs in short starts and stops and when still blends easily into the sandy beaches where it feeds and nests. Because of this, it is often heard before it is seen, a plaintive bell-like whistle from which its name is derived.
Plovers are foragers feeding on marine worms, crustaceans, and insects they gather from the sand.
Life History:After establishing their nesting territories and performing their courtship rituals, a pair of plovers will form a nest out of a shallow depression in the sand, sometimes lined with small stones or shell fragments. The pair lays a clutch of four well-camouflaged eggs which is incubated continuously as parents trade places, hatching in about 25 days. Chicks will fledge and learn to fly about 30 days after hatching. If the first clutch does not survive, the pair may try again, or separate and try again with a new mate, in the same season. These chicks may not fly until late August. At the end of the season plovers may congregate on undisturbed beaches in large groups of up to 100 before flying south in many small groups of about three to six. They may breed the first spring after hatching.
Habitat:The Piping Plover lives along the Atlantic Coast from Newfoundland to North Carolina from late March till mid-September, when it migrates to more southern beaches ranging from North Carolina to Florida, some even traveling as far south as the Bahamas.
Status:Under the Endangered Species Act, the Piping Plover has been listed as a threatened species along the Atlantic Ocean since 1986. Plovers found inland in the United States, along the Northern Plains and Great Lakes regions, are listed as endangered. The most recent surveys place the Atlantic population at less than 2000 pairs. Population declines have been attributed to human disturbance, habitat loss, and predation. As the endangered designation provides protection not only to the birds themselves but also to their habitat, other beach ecosystem inhabitants may also benefit. These include the federally endangered Roseate Tern, the threatened Northeastern Beach Tiger Beetle, the threatened Seabeach Amaranth, the Least Tern, the Common Tern, the Black Skimmer, and the Wilson's Plover.
