This family is by far the largest of the order, containing, in fact, a greater number of species than all the others combined. It is also a very old family, for some ten fossil forms have been characterized, of which two are from the lower,and one from the middle, Miocene of France; the others, from later geological horizons, are reported from New Zealand, India, and North and South America. In addition to these strictly fossil species, the largest species of the principal genus, Pallas’s Cormorant, has probably been extinct for some fifty years. Another indication of the antiquity of the family is shown by the fact that one species the recently described Harris’s Cormorant has been isolated in the Galapagos Islands for a sufficient length of time to have lost the power of flight. This interesting bird will be more fully described later.
This family embraces two genera, Phalacrocorax, the Cormorants or Shags as they are often called, with over forty species, and the monotypic Nannopterum, the Harris’s Cormorant. Their nearest of kin are the Anhingas, or Snake-birds, which have often been placed with them as a subfamily, but they differ from them in having a subcylindrical, strongly hooked bill with the cutting edges entire, instead of an elongated, simply pointed bill with serrated cutting edges. A further anatomical difference is found in the occipital style, this being large in the Cormorants and very feebly developed in the Anhingas. In both the feather covering is almost uninterrupted.
The Cormorants are birds between two and three feet in length, with an elongated, powerful body, short, stout legs, and a rather long neck. The wings are concave and rather short, reaching but little beyond the base of the tail; the third quill is longest. The tail consists of twelve or fourteen very stiff feathers. The face and throat are naked. The plumage is usually very compact, dark-colored, and glossy, with greenish or bluish green reflections. The head is often crested and during the nesting season the head and neck are often ornamented with more or less conspicuous plumes of slender, hair-like feathers which disappear after the breeding season is over.
In the matter of distribution the Cormorants as a group are almost cosmopolitan, ranging from Greenland, Alaska, and Siberia on the north to New Zealand and Kerguelen Island on the south, being, however, most abundant in the tropics. Some of the species enjoy a very wide range, as, for example, the Common Cormorant (P. Carbo), which is found in Europe, Greenland, eastern North America, all of Africa, and through northern Asia and the Indian peninsula to China and Australia, while others are restricted to single islands. About a dozen forms are found in North America, three or four in Europe, some five in Africa, and, according to Buller, about ten in New Zealand.
Cormorants are sociable birds, often congregating in flocks of immense size. Some of the species are mainly confined to ocean shores, while others make their home in inland swamps and marshes. They feed exclusively on fishes, which they are extremely dexterous in capturing. They swim well and often pursue their prey under water, but in general they select some post, projecting rock, or branch over the water, “in a position where their powers of vision enable them to discover a passing fish, upon which they pounce with a never failing aim.” Its captures are held securely with the sharp, hooked, horny point of the upper mandible, and as the throat is greatly dilatable it can swallow fish of large size.
During the nesting season the birds usually remain together and nest in communities, often of considerable size. The place selected varies somewhat with the different species and also according to the exigencies of the situation, some choosing a rocky cliff facing the sea and others low trees and bushes along low-lying shores. , The nest is usually a rude affair placed on the bare rock or ground or raised on a slight mound of sticks and weeds, or when placed in bushes of sticks loosely put together. The eggs are from three to five in number, of rather large size and pale pinkish green, with a rough crust or coating of calcareous matter. The young are very ungainly and awkward when first born and are quite helpless for some time. They feed themselves by thrusting their heads well down into their parents’ throats and “extracting the half-digested fish from their stomachs.”
Cormorants possess a considerable degree of intelligence and may be readily tamed if taken when young, evincing a warm regard for their owner. In some parts of the world, notably in China, they are taught to fish for their master. The young birds, or those not perfectly trained, have a strap or cord placed around the neck to prevent their swallowing the fish taken, and they soon learn to bring all captures to their master. After securing a sufficient quantity the strap is removed and they are permitted to fish for themselves. These trained birds usually last for about five years and have a considerable value, a well-trained male bringing some six or seven dollars.