The black head and neck with a 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.[7] 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 Cackling Goose, which slightly overlap in mass. However, the Cackling Goose is usually considerably smaller, scarcely larger than a Mallard with a much shorter neck and smaller bill.

This species ranges from 75 to 110 cm (30 to 43 in) in length and has a 127–185 cm (50–73 in) wingspan.[8] The male usually weighs 3.2–6.5 kg (7.1–14 lb), 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 lb), generally 10% smaller in linear dimensions than its male counterpart, and has a different honk. 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".[9] 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 life span in the wild of geese that survive to adulthood ranges 10–24 years.[10]
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.[10] If one dies, the other may find a new mate. The female lays from 2–9 eggs but 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.[16]

Known egg predators include coyotes,[17] Arctic Foxes, Northern Raccoons, Red Foxes, large gulls, Common Raven, American Crows and bears.[18]

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.[19]

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 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.[citation needed]

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) are taken by Coyotes, Gray Wolves, Snowy Owls, Golden Eagles and Bald Eagles.[18]
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.[28] Also, other studies show levels of stress hormones like corticosterone rise dramatically in these birds during and after a migration.[29]
From Wikipedia