|Giant Canada goose (Branta canadensis maxima) in Edmonton, Alberta|
|Canada goose distribution: Summer range (native) Year-round range (native) Wintering range (native) Summer range (introduced) Year-round range (introduced) Wintering range (introduced) Summer range (cackling goose)|
The Canada goose (Branta canadensis) is a goose with a black head and neck, white patches on the face, and a brown body. Native to arctic and temperate regions of North America, it also occasionally migrates to northern Europe, and has been introduced to Britain, New Zealand, and other temperate regions.
Extremely successful at living in human-altered areas, Canada geese have proven able to establish breeding colonies in urban and cultivated areas, which provide food and few natural predators. Because of their depredation of crops, and issues with their noise, droppings, and habit of begging for food in parks, they are widely seen as a pest species. Canada geese are also among the most commonly hunted waterfowl in North America.
Taxonomy and etymology
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 incorrectly 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.
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 (exclusive of Richardson's cackling goose, B. hutchinsii 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 co-mingle with relatively large cackling geese. Of the "true geese" (i.e. the genera Anser or 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 has a 127–185 cm (50–73 in) wingspan. Among standard measurements, the wing chord can range from 39 to 55 cm (15 to 22 in), the tarsus can range from 6.9 to 10.6 cm (2.7 to 4.2 in) and the bill can range from 4.1 to 6.8 cm (1.6 to 2.7 in). The largest subspecies is the 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 (7.3 ft). This specimen is the largest wild goose ever recorded of any species.
The male Canada goose usually weighs 2.6–6.5 kg (5.7–14.3 lb), averaging amongst all subspecies 3.9 kg (8.6 lb). The female looks virtually identical but is slightly lighter at 2.4–5.5 kg (5.3–12.1 lb), averaging amongst all subspecies 3.6 kg (7.9 lb), and generally 10% smaller in linear dimensions than the male counterparts. The female also possesses a different, and less sonorous, honk than the male.
Distribution and 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 (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. Large resident populations of Canada geese are also present in much of the San Francisco Bay Area in Northern California.
Outside North America
Canada geese have reached northern Europe naturally, as has been proved by ringing recoveries. The birds include those of the subspecies parvipes, and possibly others. Canada geese are also found naturally on the Kamchatka Peninsula in eastern Siberia, eastern China, and throughout Japan.
Canada geese have also been introduced in Europe, and have established populations in Great Britain, Ireland, the Netherlands, Belgium, France, Germany, Scandinavia, and Finland. Most European populations are non-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 the early 17th century, explorer Samuel de Champlain sent several pairs of geese to France as a present for King Louis XIII. The geese were first introduced in Britain in the late 17th century as an addition to King James II's waterfowl collection in St. James's Park. They were introduced in Germany and Scandinavia during the 20th century, starting in Sweden in 1929. In Britain they were spread by hunters, but remained uncommon until the mid-20th century. Their population grew from 2200–4000 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 subspecies canadensis, likely with some contributions from the subspecies maxima.
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 who culled excessive bird numbers. In 2011 the government removed the protection status, allowing anyone to kill the birds.
A flock of feeding Canada geese calling
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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.
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 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.
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 (a diet similar to the 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 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.
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 (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).
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 (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 temperature at which the body works. Also, other studies show levels of stress hormones like corticosterone rise dramatically in these birds during and after a migration.
The life span in the wild of geese that survive to adulthood ranges 10–24 years.
Known predators of eggs and goslings include coyotes, Arctic foxes (Vulpes lagopus), northern raccoons (Procyon lotor), red foxes (Vulpes vulpes), large gulls (Larus ssp.), common raven (Corvus corax), American crows (Corvus brachyrhynchos) and both brown (Ursus arctos) and American black bears (Ursus americanus).
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 (Canis lupus). Avian predators known to kill adults as well as young geese include snowy owls (Bubo scandiacus), golden eagles (Aquila chrysaetos) and bald eagles (Haliaeetus leucocephalus) and, though rarely on large adult geese, great horned owls (Bubo virginianus), peregrine falcons (Falco peregrinus) and gyrfalcons (Falco rusticolus). 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 (mob terrestrial predators without physical contact) 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.
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.
Canada geese are susceptible to avian bird flus, such as H5N1. A study was carried out using the HPAI virus, a H5N1 virus, the results found that the geese are susceptible to the virus and would prove useful for monitoring the spread of the virus, attributed to the high mortality of the infected birds. The study found that prior exposure to other viruses may result in some resistance to H5N1.
Relationship with humans
In North America, non-migratory Canada goose populations have been on the rise. The species is frequently found on golf courses, parking lots and urban parks, which would have previously hosted only migratory geese on rare occasions. Owing to its adaptability to human-altered areas, it has become the most common waterfowl species in North America. In many areas, non-migratory Canada geese are now regarded as pests by humans. They are suspected of being a cause of an increase in high fecal coliforms at beaches. An extended hunting season, deploying noise makers, and hazing by dogs have been used in an attempt to disrupt suspect flocks.
Since 1999, the United States Department of Agriculture Wildlife Services agency has been engaged in lethal culls of Canada geese primarily in urban or densely populated areas. The agency responds to municipalities or private land owners, such as golf courses, who find the geese obtrusive or object to their waste. Addling goose eggs and destroying nests are promoted as humane population control methods.
Canada goose is protected in Canada under the Migratory Birds Convention Act, 1994. Commercial transaction (such as buying or trading) 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.
Geese have a tendency to attack humans when they feel themselves or their goslings to be threatened. First the geese will stand erect, spread their wings and produce a hissing sound. Next, the geese will charge. They may then bite or attack with their wings.
Canada geese have been implicated in a number of bird strikes by aircraft. Their large size and tendency to fly in flocks may exacerbate their impact. In the United States, the Canada goose is the second most damaging bird strike to airplanes, with the most damaging being turkey vultures. Canada geese can cause fatal crashes when they strike an aircraft's engine. In 1995, a U.S. Air Force E-3 Sentry aircraft at Elmendorf AFB, Alaska struck a flock of Canada geese on takeoff, losing power in both port side engines. It crashed 2 miles (3.2 km) from the runway, killing all 24 crew members. The accident sparked efforts to avoid such events, including habitat modification, aversion tactics, herding and relocation, and culling of flocks. In 2009, a collision with a flock of migratory Canada geese resulted in US Airways Flight 1549 suffering a total power loss after takeoff. The pilot brought the plane to an emergency 'splash'-landing in the Hudson River, causing only minor injuries.
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.
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|Wikimedia Commons has media related to Canada Goose.|
|Wikispecies has information related to: Branta canadensis|
- Images and videos of the Canada goose on ARKive
- RSPB A to Z of UK birds
- Canada Goose Species Account – Cornell Lab of Ornithology
- Canada Goose videos, photos, and sounds at the Internet Bird Collection
- Canada Goose - BTO BirdFacts
- Rediscovery report on Giant Canada Goose from 1963 (PDF)