Canada Goose (Branta canadensis) 13-10-16
[order] Anseriformes | [family] Anatidae | [latin] Branta canadensis | [UK] Canada Goose | [FR] Bernache du Canada | [DE] Kanadagans | [ES] Barnacla Canadiense | [IT] Oca del Canada | [NL] Grote Canadese Gans
spanwidth min.: 160 cm
spanwidth 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.: 48 days
eggs min.: 4
eggs max.: 7
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.
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.
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
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.
Branta canadensis has a large range, breeding across tundra in much of Canada, Alaska (USA), and parts of the northern USA, and wintering in southern North America, including Mexico. Introduced populations are now resident in much of the USA south of the normal breeding range, as well as in a number of western European countries. It has an estimated global Extent of Occurrence of >10,000,000 km2, and has a correspondingly large global population, estimated at 1,000,000-10,000,000 individuals. Although hunting and other direct mortality takes a substantial toll, this species has increased its range and population since the 1940s1, and is thus evaluated as Least Concern. [conservation status from birdlife.org]
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.
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.