Canada Goose

Canada Goose
In Cambridge, England
Conservation status

Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Branta
Species: B. canadensis
Binomial name
Branta canadensis
(Linnaeus, 1758)
Subspecies
  • B. c. occidentalis – Dusky Canada Goose
  • B. c. fulva – Vancouver Canada Goose
  • B. c. parvipes – Lesser Canada Goose
  • B. c. moffitti – Moffitt's Canada Goose
  • B. c. maxima – Giant Canada Goose
  • B. c. interior – Interior Canada Goose
  • B. c. canadensis – Atlantic Canada Goose
Canada Goose distribution, including native (dark tones) and introduced (light tones) populations
Canada Goose summer: yellow
Canada Goose all year: green
Canada Goose winter: blue
Cackling Goose summer: pink

The Canada Goose (Branta canadensis) is a wild goose belonging to the genus Branta, which is native to arctic and temperate regions of North America, having a black head and neck, white patches on the face, and a brownish-gray body. It is often called the Canadian Goose, but that name is not the ornithological standard, or the most common name.

Contents

Taxonomy and etymology

The Canada Goose was one of the many species described by Linnaeus in his 18th-century work Systema Naturae.[2] 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 Cackling Goose was formerly considered to be a set of subspecies of the Canada Goose. A recent proposed revision by Harold Hanson suggests splitting Canada Goose into six species and 200 subspecies. The radical nature of this proposal has provoked surprise in some quarters, such as Rochard Banks of the AOU, who urges caution before any of Hanson's proposals are accepted.[3]

Description

Yellow plumage of gosling

The black head and neck with white "chinstrap" distinguish the Canada Goose from all other goose species, with the exception of the Barnacle Goose, but the latter has a black breast, and also grey, rather than brownish, body plumage.[4] There are seven subspecies of this bird, of varying sizes and plumage details, but all are recognizable as Canada Geese. Some of the smaller races can be hard to distinguish from the newly-separated Cackling Goose.

This species is 76–110 cm (30–43 in) long with a 127–180 cm (50–71 in) wingspan.[5] The male usually weighs 3.2–6.5 kg, (7–14 pounds), and can be very aggressive in defending territory. The female looks virtually identical but is slightly lighter at 2.5–5.5 kg (5.5–12 pounds), generally 10% smaller than its male counterpart, and has a different honk. An exceptionally large male of the race B. c. maxima, the "giant Canada goose" (which rarely exceed 8 kg/18 lb), weighed 10.9 kg (24 pounds) and had a wingspan of 2.24 m (88 inches). This specimen is the largest wild goose ever recorded of any species. The life span in the wild is 10–24 years.[5]

Distribution and habitat

A flock near a weir on the Humber River near Raymore Park in Toronto, Ontario.
Idaho Falls, Idaho.
Canada Geese on Spokane River, Washington.

This species is native to North America. It breeds in Canada and the northern United States in a variety of habitats. 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 Great Lakes region maintains a very large population of Canada Geese.

By the early 20th century, over-hunting and loss of habitat in the late 1800s and early 1900s 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. 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 Geese populations in some areas have grown substantially, so much so that many consider them pests (for their droppings, the 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 (such as on golf courses, public parks and beaches, and in planned communities).

Contrary to its normal migration routine, large flocks of Canada Geese have established permanent residence in the Chesapeake Bay and in Virginia's James River regions, and in the Triangle area of North Carolina (Raleigh, Durham, Chapel Hill), and nearby Hillsborough. Some flocks in Canada may even choose not to migrate, even during the winter, if food (such as leftovers from human) is constantly available throughout the season.

Outside North America

Canada Geese have reached northern Europe naturally, as has been proved by ringing recoveries. The birds are of at least the subspecies parvipes, and possibly others. Canada Geese are also found naturally on the Kamchatka Peninsula in eastern Siberia, eastern China, and throughout Japan.

Greater Canada Geese have also been introduced in Europe, and have established populations in Great Britain, the Netherlands, Belgium, Germany, and Scandinavia. Semi-tame feral birds are common in parks, and have become a pest in some areas. 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.

Canada Geese were introduced as a game bird into New Zealand and have also become a problem in some areas. The introduction of a foreign species into New Zealand is disrupting the existing biological relationship structures. On the South Island, it is estimated that the population of goose is increasing at an astonishing rate and is threatening local populations. Some even go as far to claim the goose as a pest. If the goose continues at its current high growth rate, the situation will become increasingly problematic.

Behavior

Mid-flight
Looking for food on a partially frozen pond

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.

Diet

Canada Geese are 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 grains such as wheat, beans, 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.[5] In urban cities, they are also known to pick food out of garbage bins.

Reproduction

Goslings a few days old in Loudoun County, Virginia
Courting

During the second year of their lives, Canada Geese find a mate. They are monogamous, and most couples stay together all of their lives.[5] If one is killed, the other may find a new mate. The female lays 3–8 eggs and both parents protect the nest while the eggs incubate, but the female spends more time at the nest than the male.

Known egg predators include Arctic Foxes, Northern Raccoons, Red Foxes, large gulls, Common Raven, American Crows and bears. During this incubation period, the adults lose their flight feathers, so they cannot fly until their eggs hatch after 25–28 days.

Adult geese are often seen leading their goslings in a line, usually with one parent at the front, and the other at the back. While protecting their goslings, parents often violently chase away nearby creatures, from small blackbirds to humans that approach, after warning them by giving off a hissing sound. 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. Once they reach adulthood, Canada Geese are rarely preyed on, but (beyond humans) can be taken by Coyotes, Red Foxes, Gray Wolves, Snowy Owls, Great Horned Owls, Golden Eagles and, most often, Bald Eagles.

Systematics

From behind

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.[6]

The AOU has divided the many subspecies between the two animals. To the present species were assigned:

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 an insular representative of the Canada Goose.

Relationship with humans

USDA Wildlife Services agents trap and gas geese in Seattle - 2002

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. They are suspected of being a cause of an increase in high fecal coliforms at beaches.[7] An extended hunting season and the use of noise makers 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.[8] Addling goose eggs and destroying nests are promoted as humane population control methods.[9]

In 1995, a US Air Force E-3 Sentry aircraft at Elmendorf AFB, Alaska struck a flock of Canada Geese on takeoff and crashed, killing all 24 crew. The accident sparked efforts to avoid such events, including habitat modification, aversion tactics, herding and relocation, and culling of flocks.[10] A collision with a flock of migratory[11] Canada Geese resulted in US Airways Flight 1549 suffering a total power loss after takeoff from LaGuardia Airport, New York City, New York on 15 January 2009.[12] The pilot brought the plane to an emergency 'splash'-landing in the Hudson River causing only minor injuries to the 155 passengers and crew.[13]

Geese have a tendency to defend against 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.[14]

Migration

Resting in a pond during spring migration, Ottawa, Ontario

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 a lot faster. The later birds usually spend more time at rest stops. These geese are also renowned for their V-shaped flight formation. 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.[15] Also, other studies done show corticosterone levels to rise dramatically in these birds after and during a migration. Corticosterone is known a stress hormone, so it only makes sense that when these birds are stressed by flying long distances everyday, that more corticosterone is released into their system. It is believed that a higher level of corticosterone will help the birds better manage this task.[16]

References

  1. ↑ BirdLife International (2006). Branta canadensis. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006.
  2. ↑ Linnaeus, C (1758) (in Latin). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Holmiae. (Laurentii Salvii). 
  3. ↑ Facingham, Richard (2007) Review of Harold Jackson's "THE WHITE-CHEEKED GEESE: BRANTA CANADENSIS, B. MAXIMA, B. ‘‘LAWRENSIS’’, B. HUTCHINSII, B. LEUCOPAREIA, AND B. MINIMA. TAXONOMY, ECOPHYSIOGRAPHIC RELATIONSHIPS, BIOGEOGRAPHY, AND EVOLUTIONARY CONSIDERATIONS. VOLUME 1. EASTERN TAXA" The Wilson Journal of Ornithology
  4. ↑ Audubon Society
  5. ↑ 5.0 5.1 5.2 5.3 Dewey, T; H. Lutz (2002). "Branta canadensis". University of Michigan. http://animaldiversity.ummz.umich.edu/site/accounts/information/Branta_canadensis.html. Retrieved 2007-11-18. 
  6. ↑ Stackhouse, Mark. The New Goose.
  7. ↑ Pennsylvania Department of Conservation and Natural Resources. Retrieved December 15, 2007, http://www.dcnr.state.pa.us/
  8. ↑ Board of Park Commissioners (Seattle) Meeting Minutes July 12, 2001
  9. ↑ Gregg MacDonald, Fairfax County Times (May 6, 2008). "Goose egg addling stirs concern in Reston". http://www.restontimes.com/news/2008/may/06/goose-egg-addling-stirs-concern-reston/. Retrieved 2009-06-10. 
  10. ↑ http://www.af.mil/news/airman/1297/bash.htm Air Force News article on Yukla 27
  11. ↑ Barbara Barrett (2009-06-08). "DNA shows jet that landed in Hudson struck migrating geese". http://www.mcclatchydc.com/homepage/story/69645.html. Retrieved 2009-06-08. 
  12. ↑ Bloomberg, 12 Feb. 2009 -- "Canada goose remains were found in both engines of the US Airways Group Inc. plane that made an emergency ditching in New York’s Hudson River, the National Transportation Safety Board said."
  13. ↑ http://www.nytimes.com/2009/01/16/nyregion/16strike.html?hp New York Times article on the 15 January 2009 accident
  14. ↑ Division of Wildlife (Ohio) Goose Attacks
  15. ↑ T.M. John and J.C. George. Circulatory levels of thyroxine (T4) and triidothyronine (T3) in the migratory Canada goose].
  16. ↑ Meta M. Landys. Plasma corticosterone increases during migratory restlessness in the captive white-crowned sparrowZonotrichia leucophrys gambelli.

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