Canada Goose (Branta canadensis)

Canada Goose

[order] ANSERIFORMES | [family] Anatidae | [latin] Branta canadensis | [authority] Linnaeus, 1758 | [UK] Canada Goose | [FR] Bernache du Canada | [DE] Kanadagans | [ES] Barnacla Canadiense | [NL] Canadese Gans

Subspecies

Monotypic species

Genus

The black geese of the genus Branta are waterfowl belonging to the true geese and swans subfamily Anserinae. They occur in the northern coastal regions of the Palearctic and all over North America, migrating to more southernly coasts in winter, and as resident birds in the Hawaiian Islands. Alone in the Southern Hemisphere, a self-sustaining feral population derived from introduced birds of one species is also found in New Zealand. one species has been described from subfossil remains found in the Hawaiian Islands, where it became extinct in prehistoric times. Another undescribed prehistoric species from the Big Island of Hawaii was extremely large and flightless; it is tentatively assigned to this genus due to being very peculiar. It is fairly certain that at least another species of this genus awaits discovery on the Big Island, judging from the facts that at least one species of Branta was found on every major Hawaiian island, and that remains of such birds have not been intentionally searched for on the Big IslandThe relationships of the enigmatic Geochen rhuax to this genus are unresolved. It was another prehistoric Big Island form and remains known only from some parts of a single bird’s skeleton, which were much damaged because the bird apparently died in a volcanic eruption, with the bones being found in an ash-filled depression under a lava flow. A presumed relation to the shelducks proposed by Lester Short in 1970 was generally considered highly unlikely due to that group’s biogeography, but more recently, bones of a shelduck-like bird have been found on Kauai. Whether this latter anatid was indeed a shelduck is presently undetermined. Several fossil species of Branta have been described. Since the true geese are hardly distinguishable by anatomical features, the allocation of these to this genus is somewhat uncertain. A number of supposed prehistoric grey geese have been described from North America, partially from the same sites as species assigned to Branta. Whether these are correctly assigned, meaning that the genus Anser was once much more widespread than today and that it coexisted with Branta in freshwater habitat which it today does only most rarely, is not clear. Especially in the case of B. dickeyi and B. howardae, doubts have been expressed about its correct generic assignment

Physical charateristics

Many people can recognize a Canada Goose Branta canadensis by its characteristic black head, white cheek patches, and long black neck. However, there are several different races, so a Canada Goose in one region may be quite different from a Canada Goose in another. Although there has been some disagreement about the exact number of races of Canada Geese, most scientists believe that there are 11.

Members of the different races range in size from one of the smallest geese, the Cackling Canada Goose, which can weigh as little as 1.1 kg, to the largest of all geese, the Giant Canada Goose, which can weigh up to 8 kg. Wingspans vary between about 90 cm and 2 m. The underparts range in colour from light pearl-grey to chestnut, and even blackish brown. Differences in body proportions, particularly the relative length of the neck, the body shape, and the body stance, further distinguish the different races. In general, the larger the bird, the longer the neck and the more elongated the body.

Newly hatched Canada Geese have a coat of yellow to olive down that darkens to dull grey over the first few weeks of life. As the birds grow, feathers gradually cover the down, and by the time the young geese are ready to fly in late summer, they are nearly indistinguishable from their parents. From that point on, both males and females look the same throughout the year.

Listen to the sound of Canada Goose

[audio:http://www.planetofbirds.com/MASTER/ANSERIFORMES/Anatidae/sounds/Canada Goose.mp3]

Copyright remark: Most sounds derived from xeno-canto


wingspan min.: 160 cm wingspan max.: 175 cm
size min.: 90 cm size max.: 100 cm
incubation min.: 28 days incubation max.: 30 days
fledging min.: 40 days fledging max.: 30 days
broods: 1   eggs min.: 4  
      eggs max.: 7  

Range

North America : widespread

Habitat

You can find Canada Geese on almost any type of wetland, from small ponds to large lakes and rivers. However, Canada Geese spend as much or more time on land as they do in water.

Canada Geese breed in a wide range of habitats. They prefer low-lying areas with great expanses of wet grassy meadows and an abundance of ponds and lakes that serve as refuges from foxes and other land predators. The most northerly geese breed on the treeless tundra of the Arctic. Below the treeline, the geese nest in the open boreal forest, with its scattered stands of stunted spruce and tamarack. Nesting Canada Geese are at home in many places, from sheltered mountain streams and prairie pothole ponds to golf courses and urban parks. During fall and winter, Canada Geese favour agricultural land where vast fields of cereal grains and other crops provide abundant food and relative safety from predators.

Reproduction

The Canada Geese breed earlier in the season than many birds. Breeding is timed so that the eggs hatch when the plants that the goslings, or young geese, eat have their highest nutritional value. The hatch date also allows enough time for the goslings to grow big enough to fly south before freeze-up. Canada Geese that breed in temperate areas, with mild temperatures, begin nesting as soon as conditions are favourable in spring, in some cases as early as mid-March. Canada Geese that breed in the north reach nesting areas in late April or early May, later for Arctic breeders.
Some Canada Geese breed when they are one year old, but the vast majority do not nest for the first time until they are at least two or three. Usually five to seven eggs are laid, with older birds producing more eggs than birds nesting for the first time. The female incubates the eggs for 25 to 28 days while the male stands guard nearby. In some cases, he may be several hundred metres from the nest but is always vigilant and joins the female if the nest is threatened or if she leaves the nest. During the incubation period the female leaves the nest only briefly each day to feed and drink and bathe.
Most nest sites are located near water and often on islands. Nest sites are chosen to offer some protection from exposure to wind while giving the incubating female a clear line of sight to detect approaching predators. Female Canada Geese always return to nest in the same area where their parents nested and often use the same nest site year after year.
Soon after the young have hatched, families leave their nests, sometimes walking several kilometres in a few days to reach their brood-rearing area. If the geese have nested near the seacoast, they may descend the rivers to more favourable coastal marsh areas. From the moment they leave the nest, goslings feed on grasses and sedges in meadows and along shorelines.
A pair and its goslings are an almost inseparable troupe, acting in unison. Usually the female leads the way, followed by the young, with the gander, or male, bringing up the rear. When another goose family ventures too close, both the parents and young assume threatening postures and make a lot of noise. Numbers and not the size or weight of the adults seems to be decisive-large families almost always defeat small families, which in turn defeat pairs without young. Most encounters are settled without physical contact, and prolonged fights are rare.
From six to nine weeks after hatching, depending on the race, the birds are ready to take to the air as a family unit. By this time, only about half of the goslings that hatched still survive. In the north, Canada Geese feed on berries and put on a layer of fat before their southward migration. Prior to migration, the families come together into groups of a few to several dozen families, often in coastal areas. The last of the Canada Geese linger along northern shores until early October.

Feeding habits

Unlike many waterfowl species that feed mainly in aquatic environments, Canada Geese feed mostly on land. In spring and summer, they mostly graze on the leaves of grassy plants, but they also eat a wide variety of leaves, flowers, stems, roots, seeds, and berries. The geese must consume large quantities of food to obtain the nutrients they need, and they frequently spend 12 hours a day or more feeding. During the winter, Canada Geese often feed in fields where they find an abundance of spilled corn, oats, soybeans, and other crops. When such energy-rich foods are available, they often feed in the fields for a few hours in early morning and late afternoon and spend the rest of the day resting in safety on a lake or large river. Some Canada Geese graze on lawns, in parks, and on golf courses.

Spring is a very energetically demanding time in a goose’s life, especially for breeding females. Canada Geese feed intensively during the few weeks before they leave southern agricultural areas to prepare for a period with little food when they first arrive on the northern breeding grounds. They will need sufficient reserves of fat and protein to complete migration, produce a clutch of eggs, and survive for about one month of incubation.

Video Canada Goose

httpv://www.youtube.com/watch?v=QmnoRJ2Oh6A

copyright: youtube


Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
This species from North America has been introduced in England since the middle of the 17th century and in Sweden since 1933. It has now colonised northern France, Belgium, the Netherlands and Germany. The population of the European Union is totalling 30000-35000 breeding pairs, and, despite being considered a pest in many areas, it is still introduced in some new areas
Canada Goose status Least Concern

Migration

Spring migration for northern-breeding geese begins in late winter and may take several weeks to complete. The geese move slowly northward following the advancing line of melting snow. They make several feeding stops at key areas along the way to build up reserves that will be needed for the final leg of migration and reproduction.

Fall migration begins when the water and soil begin to freeze on the breeding grounds. The trip from breeding to wintering areas is faster than the spring flight north. For example, many Atlantic population Canada Geese travel more than 1 000 km from their breeding grounds in northern Quebec to the main wintering area along the United States eastern seaboard in less than a week. In fact, scientists have tracked some geese marked with radio transmitters that have completed the trip in just one day! Families with goslings migrating south for the first time probably take longer than adults without goslings.

In addition to the annual migration from breeding to wintering grounds, Canada Geese sometimes undertake a special voyage called a moult migration. Every year, geese must replace their worn-out flight feathers. The feathers are replaced all at once, so the geese cannot fly during the four- to five-week moulting period. The best places for the geese during this time are those with lots of open water where the birds can seek refuge if threatened and where they may find a good supply of the protein-rich food needed for growing new feathers. Most of the geese that don’t breed during the season undertake this migration, which usually involves travelling north, often well beyond the normal breeding range, between late May and early June. Successful breeders moult later in the season, remaining with their young goslings, which have not begun to fly. Feral populations mostly sedentary.

Distribution map

Canada Goose distribution range map

Literature

Title Seasonal Enumeration of Fecal Coliform Bacteria from the Feces of Ring-Billed Gulls (Larus delawarensis) and Canada Geese (Branta canadensis)
Author(s): K. A. Alderisio and N. DELuca
Abstract: Water suppliers have often implicated roosting bir..[more]..
Source: APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Dec. 1999, p. 5628-5630

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