There are 11 subspecies of the canada goose (Branta canadensis) in North America and B. c. maxima is the largest of them all. It is also the most pestiferous. This huge bird was considered extinct until a small colony was discovered in the early 1960s. A breeding and introduction programme was rather too successful and it is now to be found in great numbers in many town and city parks, golf courses and other urban open spaces where water is nearby. Of all Canada geese it has the highest tolerance for people. It is also the only migratory species so once a flock has found a suitable location it stays put and increases. It feeds on aquatic plants, grass, roots, seeds and berries and a flock will graze a grassy area like sheep, neatly trimming right down to the ground. They can also devastate a grain field in no time.