Greylag GooseThe Greylag Goose,It was in pre-Linnean times known as the Wild Goose ("Anser ferus"). This species is the ancestor of domesticated geese in Europe and North America. Flocks of feral birds derived from domesticated birds are widespread. The Greylag Goose is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.
Physical appearanceThe Greylag is a large goose, 74–84 cm (29–33 in) long with a 149–168 cm (59–66 in) wingspan and a body weight of 2.3–5.5 kg (5–12 lbs). It has a large head and almost triangular bill. The legs are pink, and the bird is easily identified in flight by the pale leading edge to the wing. It has a loud cackling call, kiYAAA-ga-ga, like the domestic goose.
The western European nominate subspecies, A. a. anser, has an orange-pink bill and is slightly smaller and darker than the pink-billed Asian race, A. a. rubrirostris. Eastern European birds are often intermediate in appearance.
Interesting BehaviorThese birds are famous for their extremely strong Fixed Action Patterns behavior. FAP's are highly specific, neurologically hardwired behaviors that are exhibited virtually identically everytime a stimulus is presented. These use it to push eggs back into the nest when they have fallen out. In fact, to demonstrate how ritualized these FAPs are, if the egg is removed as the graylag goose pulls it back toward the nest with its beak, the goose will continue the movement for a certain length of time and then restart the movement after it sits down on the nest and realizes an egg is still missing.
You can confront it with a novel situation, such as a doorknob next to the nest. The FAP causes it to retrieve the doorknob as if it were an egg. The exaggeration of the sign stimulus, such as replacing a goose egg with a volleyball, causes an exaggerration of the FAP. Source: Most college level Evolution and Ecology text books. Specific source at hand (I dont want to go find my Evo/Eco books from my shelf) the Kaplan published book, "GRE EXAM Subject Test: Biology. 2007-2008 edition" on pages 214-215 in the section on "Animal Behavior and Learning", under subsection FAP.
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