5693 x 4295 px | 48,2 x 36,4 cm | 19 x 14,3 inches | 300dpi
Data acquisizione:
25 marzo 2016
Ubicazione:
Parsville Bay, Vancouver Island.British Columbia. Canada.
Altre informazioni:
It used to be a strictly coastal bird in winter, seldom leaving tidal estuaries, where it feeds on eel-grass (Zostera marina) and the seaweed, sea lettuce (Ulva). On the east coast of North America, the inclusion of sea lettuce is a recent change to their diet, brought about by a blight on eelgrass in 1931. This resulted in the near-extirpation of the brant. The few that survived changed their diet to include sea lettuce until the eelgrass eventually began to return. Brants have maintained this diet ever since as a survival strategy.[6] In recent decades, it has started using agricultural land a short distance inland, feeding extensively on grass and winter-sown cereals. This may be behaviour learnt by following other species of geese. Food resource pressure may also be important in forcing this change, as the world population has risen over 10-fold to 400, 000-500, 000 by the mid-1980s, possibly reaching the carrying capacity of the estuaries. In the breeding season, it uses low-lying wet coastal tundra for both breeding and feeding. The nest is bowl-shaped, lined with grass and down, in an elevated location, often in a small pond.
