ハイイロガン

When the flight feathers of the greylag goose fall out, it loses the ability to fly. During this period, it leads a hidden life in remote areas.
During the period when greylag goose chicks are feathered but still unable to fly, adult geese begin molting. Males molt first, followed later by females.
The greylag goose is more agile and better at swimming than domestic geese, even diving underwater. It is their ancestor but prefers to forage on land, where it feels more secure.
During rest stops, flocks of greylag geese gather together, forming groups of several thousand birds. The number of birds in a single flock can vary from several individuals to several hundred.
During the breeding season, the greylag goose feeds almost exclusively on aquatic and marsh plants, which distinguishes it from other times of the year when its diet is more varied.
Greylag geese reach very high altitudes during seasonal migrations, although they usually fly low with infrequent wing beats.
Geese produce about nine types of calls; a flock sounds like the baying of hounds.
The greylag is one of the most successful ancestors of domestic birds and a symbol of both wild nature and farming.
Males defend the family and can be aggressive guardians.
The name “greylag” refers to the fact that it migrates later than other geese—“lags” behind.

年齢

The greylag develops through several distinct stages, beginning with the embryonic stage where the embryo develops inside an egg. At birth, the young's eyes open, and they enter the chick stage, which lasts from 1 to 2 months and is characterized by a covering of yellow down. Following this, the species enters the rapid growth post-chick stage, lasting from 2 months to 2 years. The greylag reaches sexual maturity at an age ranging from 4 weeks and 2 days to 3 years. The adult stage, where the bird is capable of reproduction, lasts from 2 to 25 years. A typical lifespan for the species is from 15 to 25 years, although the maximum recorded lifespan is 28 years. The theoretical lifespan ranges from 22 years and 4 months to 31 years and 11 months.

表現型

Greylag geese have soft yellow down that protects the young from cold and camouflages them in grass. The young after a period of rapid growth display grey feathers without bright white spots on the belly. Adult greylags possess a strong orange bill for grazing plants, and powerful pink legs with webbing. The adult’s plumage is grey, with white patches on the belly and under the tail; they also have large wings for long flights.

生理学

The greylag goose measures between 71 and 89 centimeters in body length, with a weight ranging from 3.75 to 4.84 kilograms, and a wingspan of 1.55 meters. The embryo stage has a body mass of 140 to 170 grams; the chick stage presents individuals with a body mass between 90 grams and 0.85 kilograms and a body length of 15 to 35 centimeters. During the rapid growth stage, the young have a body mass from 1.8 to 3.2 kilograms and a body length from 60 to 80 centimeters. Adult greylags weigh between 3.2 and 4.5 kilograms and measure 76 to 89 centimeters in body length.

生息地

Greylag Geese inhabit temperate mixed forests with warm summers and many oak, birch, and maple trees, as well as flooded meadows where water frequently covers the ground and there is abundant grass, shallow coastal waters supporting crabs, taiga characterized by cold winters and coniferous trees such as spruce and pine, and tundra with very cold temperatures, a short summer, sparse vegetation, and plentiful moss. The species occupies freshwater bodies, lakes, ponds, marshes, swamps, marine environments, coastal waters, and land. The climate is consistently very wet with frequent rain and high humidity; the summers are often cool and rainy with snow in winter, or warm with abundant rainfall, or simply warm, or comfortable with temperatures between 20 and 25 degrees Celsius. Greylag geese live at elevations up to 1.5 kilometers above sea level.

隠れ家

The greylag is found on the edge of a body of water among grass or reeds. The species builds or uses a nest as a shelter, which is a nest-like structure for laying eggs and raising young. Nesting materials include grass, down, and twigs.

地理

Greylag Geese are found within the Palearctic biogeographical region, encompassing both freshwater and marine environments. The species occupies several ecosystems, including Celtic broadleaf forests, broadleaf forests of Western Europe, Caledonian coniferous forests, beech forests of the English lowlands, Baltic mixed forests, and European Atlantic mixed forests.

餌

The greylag goose feeds on plants, including grass on meadows, leaves, seeds, roots, and aquatic plants; its feeding method involves nipping at plants with its beak. The species’ diet consists of grass, aquatic plants, cereals, roots, seeds, algae, coniferous cones, grain, and vegetation. The daily food requirement ranges from 400 grams to 0.8 kilograms. It obtains food through foraging and grazing. The greylag goose also consumes beetles, flies, membranous insects, butterflies, amphipods, ribbon worms, snails, and polychaetes. Predators of the greylag include eagles, wolves, and members of the weasel family.

繁殖

The goose forms a pair for life, with the male guarding the female. The female builds a nest on the ground and lays 4–6 eggs, and embryo development takes 4 weeks. The female incubates the eggs while the male guards the nest. The brood size is 4–12 chicks, which both parents lead. Maturity occurs at an age of 2 to 3 years, and the breeding interval is 1 year.