The Bittern is a very courageous bird; it will defend itself energetically against any bird of prey, against dogs, and even man. It is found all over Europe. Four British species are described--_B. stellaris_, _B. lentiginosus_, _B. minutus_, and _B. comatus_. The CRANE (_Grus_), which forms a genus among the Cultrirostres, is characterised by a bill much longer than the head, stout, straight, tapering, compressed, and pointed, but always slightly cleft; feet long; tibia bare for a fourth of its length, covered with hexagonal scales; toes, four; back toe short, which does not reach the ground; wings long and pointed. The Cranes are essentially migratory birds, and possess wonderful requisites; for, in addition to prolonged powers of flight, they enjoy the valuable faculty of being able to endure total abstinence from food for several days--a faculty which, we may remark, is common to most of the Wader tribe, though in a less degree. There are three species described--the Ash-coloured Crane, the Crested Crane, and the Demoiselle Crane. The Ash-coloured Crane (_Grus cinerea_), Fig. 142, is a fine bird, attaining nearly five feet in height. With the exception of the neck, which is black, all the rest of its body is of a uniform ashy-grey colour. The carriage of the bird is noble and graceful, and the feathers on its rump, which rise up in undulating clusters, add much to its elegance. These Cranes are periodical visitors to France; they arrive in Europe in the month of April or May, passing the fine weather in more northern countries. Towards the middle of October, on the arrival of the first cold weather, they leave us, in order to winter in Egypt, Abyssinia, or even Southern Asia. They travel in flocks, numbering sometimes as many as three or four hundred birds; generally they arrange themselves in two lines, so as to form an isosceles triangle, or a sort of wedge with the point in front--the most convenient formation for cleaving the air with the least amount of fatigue. From time immemorial people have been fond of saying that these birds intrust the care of their guidance to a chief, who, after having led the way for a certain time, and becoming wearied, surrenders his charge to one of his companions and passes to the rear of the band, where, like a new Cincinnatus, he resumes the position of a simple citizen. The fact is, that the leader of the two files changes perhaps ten times in a minute, and the apex of the angle is occupied in succession by every Crane in the flock within a very short space of time. [Illustration: Fig. 142.--Ash-coloured Crane (_Grus cinerea_, Temm.).]