Canada goose

Appearance

The black head and neck with a white "chinstrap" distinguish the Canada goose from all other goose species, with the exception of the cackling goose and barnacle goose, but the latter has a black breast, and also grey, rather than brownish, body plumage.

There are seven subspecies of this bird, of widely varying sizes 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 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 co-mingle with relatively large cackling geese. Of the "true geese", 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 in length and has a 127–185 cm wingspan. The male goose usually weighs 2.6–6.5 kg, averaging amongst all subspecies 3.9 kg, and can be very aggressive in defending territory. The female looks virtually identical but is slightly lighter at 2.4–5.5 kg, averaging amongst all subspecies 3.6 kg, and generally 10% smaller in linear dimensions than the male counterparts. The female also possesses a different, and less sonorous, honk than the male. Among standard measurements, the wing chord can range from 39 to 55 cm, the tarsus can range from 6.9 to 10.6 cm and the bill can range from 4.1 to 6.8 cm. The largest subspecies is the "B. c. maxima", or the "giant Canada goose", and the smallest is "B. c. parvipes", or the "lesser Canada goose". An exceptionally large male of race "B. c. maxima", which rarely exceed 8 kg, weighed 10.9 kg and had a wingspan of 2.24 m. This specimen is the largest wild goose ever recorded of any species.

Canada goose is protected in Canada under the "Migratory Birds Convention Act, 1994". Commercial transaction are prohibited. The possession, hunting, and interfering with the activity of the animals are restricted by law. Environment Canada's Wildlife Enforcement Officers have the responsibility for enforcing the legislation.

Naming

The Canada goose was one of the many species described by Carl Linnaeus in his 18th-century work "Systema Naturae". It belongs to the "Branta" genus of geese, which contains species with largely black plumage, distinguishing them from the grey species of the "Anser" genus. The specific epithet "canadensis" is a New Latin word meaning "from Canada". According to the "Oxford English Dictionary", the first citation for the 'Canada goose' dates back to 1772. The Canada goose is often colloquially referred to as the "Canadian goose".

The cackling goose was originally considered to be the same species or a subspecies of the Canada goose, but in July 2004 the American Ornithologists' Union's Committee on Classification and Nomenclature split the two into two species, making cackling goose into a full species with the scientific name "Branta hutchinsii". The British Ornithologists' Union followed suit in June 2005.

The AOU has divided the many subspecies between the two species. The subspecies of the Canada goose were listed as:
⤷  Atlantic Canada goose, "Branta canadensis canadensis"
⤷  Interior Canada goose, "Branta canadensis interior"
⤷  Giant Canada goose, "Branta canadensis maxima"
⤷  Moffitt's Canada goose, "Branta canadensis moffitti"
⤷  Vancouver Canada goose, "Branta canadensis fulva"
⤷  Dusky Canada goose, "Branta canadensis occidentalis"
⤷  part of "lesser complex", "Branta canadensis parvipes"

The distinctions between the two geese have led to confusion and debate among ornithologists. This has been aggravated by the overlap between the small types of Canada goose and larger types of cackling goose. The old "lesser Canada goose" was believed to be a partly hybrid population, with the birds named "taverneri" considered a mixture of "minima", "occidentalis" and "parvipes". In addition, it has been determined that the barnacle goose is a derivative of the cackling goose lineage, whereas the Hawaiian goose is derived from the Canada goose.

Distribution

This species is native to North America. It breeds in Canada and the northern United States in a variety of habitats. The Great Lakes region maintains a very large population of Canada geese. Canada geese occur year-round in the southern part of their breeding range, including most of the eastern seaboard and the Pacific coast. Between California and South Carolina in the southern United States and northern Mexico, Canada geese are primarily present as migrants from further north during the winter.

By the early 20th century, over-hunting and loss of habitat in the late 19th century and early 20th century 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. Its first director, Harvey K. Nelson, talked Forrest Lee into leaving Minnesota. Forrest Lee would 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 "occidentalis", may still be declining.

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, man-made bodies of water near food sources, such as those found on golf courses, in public parks and beaches, 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-around feature of such urban environments.

Contrary to its normal migration routine, large flocks of Canada geese have established permanent residence in Esquimalt, British Columbia, on Chesapeake Bay, in Virginia's James River regions, and in the Triangle area of North Carolina, 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. Large resident populations of Canada geese are also present in much of the San Francisco Bay Area in Northern California.In 2000, the North American population for the geese was estimated to be between 4 million and 5 million birds. A 21-year study in Wichita, Kansas, found the number of geese increase from 1,600 to 18,000 birds.

Behavior

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 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 California to the Great Lakes, some of the population has become non-migratory due to adequate winter food supply and a lack of former predators.

Males exhibit agonistic behaviour both on and off breeding and nesting grounds. This behavior rarely involves interspecific killing. One documented case involved a male defending its nest from a brant goose 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.

Habitat

This species is native to North America. It breeds in Canada and the northern United States in a variety of habitats. The Great Lakes region maintains a very large population of Canada geese. Canada geese occur year-round in the southern part of their breeding range, including most of the eastern seaboard and the Pacific coast. Between California and South Carolina in the southern United States and northern Mexico, Canada geese are primarily present as migrants from further north during the winter.

By the early 20th century, over-hunting and loss of habitat in the late 19th century and early 20th century 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. Its first director, Harvey K. Nelson, talked Forrest Lee into leaving Minnesota. Forrest Lee would 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 "occidentalis", may still be declining.

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, man-made bodies of water near food sources, such as those found on golf courses, in public parks and beaches, 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-around feature of such urban environments.

Contrary to its normal migration routine, large flocks of Canada geese have established permanent residence in Esquimalt, British Columbia, on Chesapeake Bay, in Virginia's James River regions, and in the Triangle area of North Carolina, 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. Large resident populations of Canada geese are also present in much of the San Francisco Bay Area in Northern California.Salinity plays a role in the growth and development of goslings. Moderate to high salinity concentrations without fresh water results in slower development, growth and saline-induced mortality. Goslings are susceptible to saline-induced mortality before their nasal salt glands become functional, with the majority occurring before the sixth day of life.

Reproduction

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 2–9 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.

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.

The incubation period, in which the female incubates while the male remains nearby, lasts for 24–28 days after laying. As the annual summer molt also takes place during the breeding season, the adults lose their flight feathers for 20–40 days, regaining flight at about the same time as their goslings start to fly.

As soon as the goslings hatch they are immediately capable of walking, swimming and finding their own food. 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 that approach, after warning them by giving off a hissing sound and will then attack with bites and slaps of the wings if the threat does not retreat or has seized a gosling. Most of the species that prey on eggs will also take a gosling. Although parents are hostile to unfamiliar geese, they may form groups of a number of goslings and a few adults, called crèches.

The offspring enter the fledging stage any time from 6 to 9 weeks of age. They do not leave their parents until after the spring migration, when they return to their birthplace.

Food

Canada geese are primarily herbivores,...hieroglyph snipped... 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 silt at the bottom of the body of water. It also feeds on aquatic plants, such as seaweeds. In urban areas, they are also known to pick food out of garbage bins.

Predators

Known predators of eggs and goslings include coyotes, Arctic foxes, northern raccoons, red foxes, large gulls, common raven, American crows and both brown and American black bears.

Once they reach adulthood, due to their large size and often aggressive behavior, Canada geese are rarely preyed on, although prior injury may make them more vulnerable to natural predators. Beyond humans, adults can be taken by coyotes and gray wolves. Avian predators known to kill adults as well as young geese include snowy owls, golden eagles and bald eagles and, though rarely on large adult geese, great horned owls, peregrine falcons and gyrfalcons. Adults are quite vigorous at displacing potential predators from the nest site, with predator prevention usually falling to the larger male of the pair. Males usually attempt to draw attention of approaching predators and will toll often in accompaniment with males of other goose species. Eagles of both species frequently cause geese to fly off in mass from some distance, though in other instances geese may seem unconcerned at perched bald eagles nearby. Canada geese are quite wary of humans where they are regularly harvested but can otherwise become habituated to fearlessness towards humans, especially where they are fed by them.

Migration

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. 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 will 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.

Canada geese fly in a distinctive V-shaped flight formation, with an altitude of 1 km for migration flight. The maximum flight ceiling of Canada geese is unknown, but they have been reported at 9 km.

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 will help the body cope with the longer journey. The increased T4 levels are also associated with increased muscle mass 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 temperature at which the body works....hieroglyph snipped... Also, other studies show levels of stress hormones like corticosterone rise dramatically in these birds during and after a migration.