Even now a pair of greylag geese hand-reared by a neighbouring farmer are making it hazardous for any vehicle to drive along the lane past his house. Hissing, bowing and weaving, the gander is quite ready to take on any car that comes along.
Grouse are particularly fierce: males often attack, and sometimes kill, each other, pecking at the back of rivals' heads. The other day, on a Yorkshire moor, I came across a cock grouse and a man in what looked like one-to-one conversation. Enquiries revealed that the bird, which must have weighed all of a pound and a half, had just physically attacked the 12-stone human being, who was innocently going for a stroll.
Females have a different method of protecting their young. Pheasants, partridges, duck and grouse will all simulate injury, fluttering pathetically away across a field as if with a broken wing, to decoy intruders away from their broods, before flying off.