Canada Goose

识别特征

The black head and neck with a white "chinstrap" distinguish the Canada goose from all other goose species except the cackling goose and barnacle goose (the latter, however, has a black breast and gray rather than brownish body plumage). Some Canadian geese come with a pepper-spotted or brown neck with brown plumage, and these are assumed to be a leucistic variety.<p>The seven subspecies of this bird vary widely in size and plumage details, but all are recognizable as Canada geese. Some of the smaller races can be hard to distinguish from the cackling goose, which slightly overlap in mass. However, most subspecies of the cackling goose (exclusive of Richardson's cackling goose, B. h. hutchinsii) are considerably smaller. The smallest cackling goose, B. h. minima, is scarcely larger than a mallard. In addition to the size difference, cackling geese also have a shorter neck and smaller bill, which can be useful when small Canada geese comingle with relatively large cackling geese. Of the "true geese" (i.e., the genera Anser and Branta), the Canada goose is on average the largest living species, although some other species that are geese in name, if not of close relation to these genera, are on average heavier, such as the spur-winged goose and Cape Barren goose.Canada geese range from 75 to 110 cm (30 to 43 in) in length and have a 127–185 cm (50–73 in) wingspan. Among standard measurements, the wing chord can range from .mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}39 to 55 cm (15+1⁄2 to 21+1⁄2 in), the tarsus can range from 6.9 to 10.6 cm (2+11⁄16 to 4+3⁄16 in) and the bill can range from 4.1 to 6.8 cm (1+5⁄8 to 2+11⁄16 in). The largest subspecies is B. c. maxima, or the giant Canada goose, and the smallest (with the separation of the cackling goose group) is B. c. parvipes, or the lesser Canada goose. An exceptionally large male of race B. c. maxima, which rarely exceed 8 kg (18 lb) , weighed 10.9 kg (24 lb) and had a wingspan of 2.24 m (7 ft 4 in). This specimen is the largest wild goose ever recorded of any species.<p>The male Canada goose usually weighs 2.6–6.5 kg (5+3⁄4–14+1⁄4 lb), averaging amongst all subspecies 3.9 kg (8+1⁄2 lb). The female looks virtually identical, but is slightly lighter at 2.4–5.5 kg (5+1⁄4–12+1⁄4 lb), averaging amongst all subspecies 3.6 kg (8 lb), and generally 10% smaller in linear dimensions than the male counterparts. The honk refers to the call of the male Canada goose, while the hrink call refers to the female goose. The calls are similar, however, the hrink is shorter and more high-pitched than the honk of males. When agitated or aggressively defending territory, Canada geese will typically initiate an encounter with a high-pitched hiss. Canada geese communicate with ten different vocalizations, each in response a different situation confronting them.

分类信息

学名

Branta canadensis

命名信息

(Linnaeus, 1758)

目

Anseriformes

科

Anatidae

属

Branta

分布与栖息地

This species is native to North America. It breeds in Canada and the northern United States in a wide range of habitats. The Great Lakes region maintains a large population of Canada geese. Canada geese live year-round in the southern part of their breeding range, including the northern half of the United States' eastern seaboard and Pacific Coast, and areas in between. Between California and South Carolina in the southern United States and in northern Mexico, Canada geese are mainly present as migrants from further north during the winter.<p>By the early 20th century, overhunting and loss of habitat in the late 19th and early 20th centuries had resulted in a serious decline in the numbers of this bird in its native range. The giant Canada goose subspecies was believed to be extinct in the 1950s until, in 1962, a small flock was discovered wintering in Rochester, Minnesota, by Harold Hanson of the Illinois Natural History Survey. In 1964, the Northern Prairie Wildlife Research Center was built near Jamestown, North Dakota. Its first director, Harvey K. Nelson, talked Forrest Lee into leaving Minnesota to head the center's Canada goose production and restoration program. Forrest soon had 64 pens with 64 breeding pairs of screened, high-quality birds. The project involved private, state, and federal resources and relied on the expertise and cooperation of many individuals. By the end of 1981, more than 6,000 giant Canada geese had been released at 83 sites in 26 counties in North Dakota. With improved game laws and habitat recreation and preservation programs, their populations have recovered in most of their range, although some local populations, especially of the subspecies B. c. occidentalis, may still be declining.[citation needed]<p>In recent years, Canada goose populations in some areas have grown substantially, so much so that many consider them pests for their droppings, bacteria in their droppings, noise, and confrontational behavior. This problem is partially due to the removal of natural predators and an abundance of safe, human-made bodies of water near food sources, such as those found on golf courses, in public parks and beaches, on sports fields, and in planned communities. Due in part to the interbreeding of various migratory subspecies with the introduced non-migratory giant subspecies, Canada geese are frequently a year-round feature of such urban environments.<p>Contrary to its normal migration routine, large flocks of Canada geese have established permanent residence along the Pacific coast of North America from British Columbia's Lower Mainland and Vancouver Island area south to the San Francisco Bay area of Northern California. There are also resident Atlantic coast populations, such as on Chesapeake Bay, in Virginia's James River regions, and in the Triangle area of North Carolina (Raleigh, Durham, Chapel Hill), and nearby Hillsborough. Some Canada geese have taken up permanent residence as far south as Florida, in places such as retention ponds in apartment complexes. In 2015, the Ohio population of Canada geese was reported as roughly 130,000, with the number likely to continue increasing. Many of the geese, previously migratory, reportedly had become native, remaining in the state even in the summer. The increase was attributed to a lack of natural predators, an abundance of water, and plentiful grass in manicured lawns in urban areas. Canada geese were eliminated in Ohio following the American Civil War but were reintroduced in 1956 with 10 pairs. The population was estimated at 18,000 in 1979. The geese are considered protected, though a hunting season is allowed from September 1–15, with a daily bag limit of five. The Ohio Department of Natural Resources recommends several non-lethal scare and hazing tactics for nuisance geese, but if such methods have been used without success, they may issue a permit which can be used from March 11 through August 31 to destroy nests, conduct a goose roundup or exterminate geese.<p>Canada geese have reached Northern Europe naturally, as has been proved by ringing recoveries. The birds include those of the subspecies B. c. parvipes, and possibly others. These geese are also found naturally on the Kamchatka Peninsula in eastern Siberia, and eastern China.[citation needed]<p>Canada geese have also been introduced in Europe in the early 17th century by explorer Samuel de Champlain who sent several pairs of geese to France as a present for King Louis XIII. The geese were first introduced in Great Britain in the late 17th century as an addition to King James II's waterfowl collection in St. James's Park. By the middle of the 18th century, the Canada geese have established populations in France and Great Britain, but also in Ireland. They were also introduced in the Netherlands, Belgium, Germany, Scandinavia, and Finland in the 20th Century, starting in Sweden in 1929. Most European populations are not migratory, but those in more northerly parts of Sweden and Finland migrate to the North Sea and Baltic coasts. Semi-tame feral birds are common in parks, and have become a pest in some areas. In Great Britain, they were spread by hunters, but remained uncommon until the mid-20th century. Their population grew from 2,200 to 4,000 birds in 1953 to an estimated 82,000 in 1999, as changing agricultural practices and urban growth provided new habitat. European birds are mostly descended from the nominate subspecies B. c. canadensis, likely with some contributions from the subspecies B. c. maxima.<p>Canada geese were introduced as a game bird into New Zealand in 1905. They have become a problem in some areas by fouling pastures and damaging crops. They were protected under the Wildlife Act 1953 and the population was managed by Fish and Game New Zealand, which culled excessive bird numbers. In 2011, the government removed the protection status, allowing anyone to kill the birds.

迁徙

Complete migrants

行为

Like most geese, the Canada goose is naturally migratory with the wintering range being most of the United States. The calls overhead from large groups of Canada geese flying in a V-shaped formation signal the transitions into spring and autumn. In some areas, migration routes have changed due to changes in habitat and food sources. In mild climates from southwestern British Columbia to California to the Great Lakes, some of the population has become nonmigratory due to adequate winter food supply and a lack of former predators.[citation needed]<p>Males exhibit agonistic behavior both on and off breeding and nesting grounds. This behavior rarely involves interspecific killing. One documented case involved a male defending his nest from a brant that wandered into the area; the following attack lasted for one hour until the death of the brant. The cause of death was suffocation or drowning in mud as a direct result of the Canada goose's pecking the head of the brant into the mud. Researchers attributed it to high hormone levels and the brant's inability to leave the nesting area.<p>Canada geese are primarily herbivores, although they sometimes eat small insects and fish. Their diet includes green vegetation and grains. The Canada goose eats a variety of grasses when on land. It feeds by grasping a blade of grass with the bill, then tearing it with a jerk of the head. The Canada goose also eats beans and grains such as wheat, rice, and corn when they are available. In the water, it feeds from aquatic plants by sliding its bill at the bottom of the body of water. It also feeds on aquatic plant-like algae, such as seaweed.<p>In urban areas, it is also known to pick food out of garbage bins. They are also sometimes hand-fed a variety of grains and other foods by humans in parks. Canada geese prefer lawn grass in urban areas. They usually graze in open areas with wide clearance to avoid potential predators.<p>During the second year of their lives, Canada geese find a mate. They are monogamous, and most couples stay together all of their lives. If one dies, the other may find a new mate. The female lays from two to nine eggs with an average of five, and both parents protect the nest while the eggs incubate, but the female spends more time at the nest than the male.<p>Its nest is usually located in an elevated area near water such as streams, lakes, ponds, and sometimes on a beaver lodge. Its eggs are laid in a shallow depression lined with plant material and down.<p>The incubation period, in which the female incubates while the male remains nearby, lasts for 24–32 days after laying. Canada geese can respond to external climatic factors by adjusting their laying date to spring maximum temperatures, which may benefit their nesting success.As the annual summer molt also takes place during the breeding season, the adults lose their flight feathers for 20–40 days, regaining flight about the same time as their goslings start to fly.<p>As soon as the goslings hatch, they are immediately capable of walking, swimming, and finding their own food (a diet similar to that of adult geese). Parents are often seen leading their goslings in a line, usually with one adult at the front and the other at the back. While protecting their goslings, parents often violently chase away nearby creatures, from small blackbirds to lone humans who approach: first giving a warning hiss, and then attacking with bites and slaps of the wings. Although parents are hostile to unfamiliar geese, they may form groups of a number of goslings and a few adults, called crèches.<p>The offspring enter the fledgling stage any time from six to nine weeks of age. They do not leave their parents until after the spring migration, when they return to their birthplace.<p>Canada geese are known for their seasonal migrations. Most Canada geese have staging or resting areas where they join up with others. Their autumn migration can be seen from September to the beginning of November.[citation needed] The early migrants have a tendency to spend less time at rest stops and go through the migration much faster. The later birds usually spend more time at rest stops. Some geese return to the same nesting ground year after year and lay eggs with their mate, raising them in the same way each year. This is recorded from the many tagged geese which frequent the East Coast.<p>Canada geese fly in a distinctive V-shaped flight formation, with an altitude of 1 km (3,000 feet) for migration flight. The maximum flight ceiling of Canada geese is unknown, but they have been reported at 9 km (29,000 feet).<p>Flying in the V formation has been the subject of study by researchers. The front position is rotated since flying in front consumes the most energy. Canada geese leave the winter grounds more quickly than the summer grounds. Elevated thyroid hormones, such as T3 and T4, have been measured in geese just after a big migration. This is believed because of the long days of flying in migration the thyroid gland sends out more T4 which help the body cope with the longer journey. The increased T4 levels are also associated with increased muscle mass (hypertrophy) of the breast muscle, also because of the longer time spent flying. It is believed that the body sends out more T4 to help the goose's body with this long task by speeding up the metabolism and lowering the temperature at which the muscles work. Also, other studies show levels of stress hormones such as corticosterone rise dramatically in these birds during and after a migration.

保护状况

种群趋势

rising