Birds – The Penguin

IT first sight it might seem that the Penguins were quite closely related to the Auks and their allies, since they have approximately the same shape and much the same habits of life ; but the more closely the Penguins are studied the clearer become the differences, and it is soon seen that the resemblance is hardly more than accidental or superficial; in fact, taking everything into account, the Penguins constitute one of the most distinct and remarkable groups into which birds are divided. They are flightless birds, of moderate or large size, confined exclusively to the Antarctic region, where they occupy in a measure the position filled in the opposite hemisphere by the Auks and their immediate relatives. The wings are reduced in size and modified by the flattening and consolidation of the bones until the product is a perfect swimming paddle, for which purpose they are exclusively used. These birds are expert swimmers and divers, but unlike most other aquatic birds, they make no use of the feet in swimming beyond employing them as a rudder. The wings, or “flippers,” as they might perhaps be called, are moved alternately, thus producing a screw motion, and the appearance of the birds in the water is little short of marvelous.

Moseley, the naturalist of the Challenger expedition, who mistook them at first for small porpoises or dolphins, says : ” They came along in a shoal of fifty or more, from seawards toward the shore at a rapid pace, by a series of successive leaps out of the water, and splashes into it again, describing short curves in the air, taking headers out of the water and headers into it again; splash, splash, went this marvelous shoal of animals, till they went splash through the surf on to the black stony beach, and there struggled and jumped up amongst the boulders and revealed themselves as wet and dripping Penguins, for such they ware.”

Anatomy. —The bones of the wing, as might be expected from the altered function of this organ, show very great modifications. The shoulder-blade (scapula) is of enormous size and affords attachment for the powerful muscles of the shoulder joint. The coracoid bone is also of great strength. The other bones of the wing are much compressed laterally and are more or less fused or anchylosed until there is relatively little freedom of motion between them. The shoulder joint is as perfect in Penguins as in other birds, but the remaining portions of the wing are so arranged as to “almost entirely exclude those movements of flexion and extension which are essential to an organ of flight,” and it is moved as an almost rigid body. However, most of the muscles which are present in the wing of a flying bird are represented in the wing of a Penguin by tendons, showing beyond question that the present flightless condition has been produced by degeneration from an ancestor which enjoyed the power of flight.

While the bones of the leg are modified to a less extent than are those of the wing, they nevertheless present a number of peculiarities not met with in other birds. Thus the knee-cap (patella) is larger than in most birds, while the tarso-metatarsus is shorter and broader than in any known bird except the Frigate-bird, and retains its three elements in an incompletely fused condition . In all other birds the fusion of these bones is not only complete, but in many cases is carried to such an extent that all evidence of individuality has disappeared and it appears as a solid bone. This incomplete fusion of the metatarsal bones was present in the earliest known fossil representative (Palaeeudyptes antarcticus from the Eocene of New Zealand), which was thought to prove that modern Penguins have directly inherited this feature, though with fuller knowledge this seems to require modification. The toes, four in number, are all directed forward, a condition not unknown among other birds, yet of rather uncommon occurrence. When on land Penguins stand very erect, with drooping wings, and the whole of the metatarsus is applied to the ground, thus making them very “flat-footed.”

Among other structural features it may be mentioned that the beak is usually long and straight, with its sides compressed and more or less grooved, and its tip never hooked but rather sharply pointed. The nostrils are slit-like and located within lateral grooves, while the palate is also of the split (schizognathous) type. The breast-bone, which is about half as broad as it is long, has a pair of notches at the back and a well-developed keel in front. Of the four toes the first is very small and joined to the inner sides of the metatarsus, while the other three are strong and completely webbed.

The feather-covering in the Penguins also affords another interesting feature. With the possible exception of the Screamers they are the only known birds in which there are no bare spaces (apteria). The feathers themselves are narrow, lanceolate, with a very broad, flat shaft, convex beneath, with the ordinary furrow of the lower surface usually wanting. The aftershaft is distinctly recognizable and is similar to the shaft. No specially formed quills can be detected in the wings, but in the tail stiff quills are usually distinguishable. Beneath the feathers or just under the skin are powerful muscles by means of which the water can be entirely shaken from the feathers as the birds emerge from the icy sea, — a fortunate provision, for otherwise, in the frigid temperature in which they live, they would be masses of ice in a few moments. The body temperature, stated by Mr. W. Eagle Clarke to be 102°–103° F., for the Adelie Penguin, is further equalized and maintained by a dense layer of fat beneath the skin not unlike the layer of blubber in seals and cetaceans. The moult takes place quickly, the plumage peeling off, as it were, in large patches, and disclosing to view a short undergrowth of new feathers, the whole process, according to Buller, requiring only two or three days. Other observers place the length of time of actual shedding as within ten days or two weeks. The moult of the King Penguin has been observed in the gardens of the Zoological Society of London, and toward the close of the period the bird was always seen to be busy picking the feathers off, nearly all being removed by its bill, not pulled, but pushed off. “When the moult was nearly completed and only a few dried-up feathers adhered to the back and upper side of the middle of the wings, the epidermal covering of the orange-colored patches on the lower mandibles loosened and came off like pieces of parchment or dry bladder.” This shedding of portions of the epidermal covering is well known in certain Auks and Puffins, but had not been observed previously in members of this group.

As already mentioned, when the Penguins are on land they stand erect, some species even holding the neck and head stretched vertically upward. They have the habit of disposing themselves in lines along the rocks or edges of the ice-floes, resembling at this time long lines of soldiers. Although they are extremely awkward in walking, especially when hurried, they nevertheless manage to get over the ground with considerable speed. Kidder, who observed them on Kerguelen Island, describes the gait as follows: “No living thing that I ever saw expresses so graphically a state of hurry as a Penguin, when trying to escape. Its neck is stretched out, flippers whirling like the sails of a windmill, and body wagging from side to side, its short legs make stumbling and frantic efforts to get over the ground. There is such an expression of anxiety written all over the bird; it picks itself up from every fall, and stumbles again with such an air of having an arm full of bundles, that it escapes capture quite as often by the laughter of the pursuer as by its own really quite considerable speed.” But they are preeminently birds of the sea, swimming and diving with the greatest facility, coming to the surface and disappearing again with such rapidity that it is almost impossible to say if it be bird or fish. The length of time that one can remain under water is a little more than a minute, which is not an extraordinary accomplishment as compared with certain other birds. Their food consists entirely of fish, crustaceans, cephalopods, etc., which they seek in the open ocean, heed-less of storm and waves, for it “must be hard weather indeed when a Penguin goes in search of shelter, as he enjoys the wildest surf and loves the roaring gale.”

During the nesting period they resort mainly to the wildest and most inaccessible islands and isolated rocks in the southern seas. Here they come, or at least once did, in countless thousands. The nests of some of the species are placed on the ground, while others nest mainly in burrows or holes among the rocks, and it is said of at least the King Penguin that the egg is carried in a pouch or fold of skin between the legs, being laid down only for the purpose of changing it from one parent to the other. When on the ground the nests are rude affairs, consisting of a few grasses or are simply slight depressions scratched in the earth by the birds. The burrowing species of the Falkland Islands have modified their habits to some extent since the advent of civilization, now making these holes ten or fifteen feet long. The eggs are usually two in number, but apparently in some species there is but one; they are white or greenish white in color and possess a very thick shell. Both parents take part in the incubation of the eggs and attend to the needs of the young with great care until they are able to shift for themselves. Notwithstanding this extreme care for the preservation of the young birds, Gould tells us that heavy gales of wind frequently destroy them in great numbers, hundreds occasionally being found dead on the beach after a storm. When sitting on the eggs or brooding the young, the old birds sit closely and if approached too near resent the intrusion with their powerful, sharp bills and are capable of inflicting severe wounds.

Penguin Rookeries. — Moseley gives the following graphic account of his visit to a large colony of Rock-hoppers: “You plunge into one of the lanes in the tall grass which at once shuts the surroundings from your view. The stench is overpowering, the yelling of the birds perfectly terrifying. The nests are placed so thickly that you cannot help treading on eggs and young birds at almost every step. A parent bird sits on each nest, with its sharp beak erect and open, ready to bite, yelling savagely, ‘Caa, Caa, Urr, Urr,’ its red eyes gleaming, and its plumes at half cock, quivering with rage. No sooner are your legs within reach than they are furiously bitten, often by two or three birds at once. At first you try to avoid the nests, but soon find that impossible; then maddened almost by the pain, stench, and noise, you have recourse to brutality.” Their gregarious habits and their inability to escape when on land have caused them to be greatly persecuted by man, as both eggs and birds are eagerly sought as food; for while neither birds nor eggs have a very delicate flavor, they are nevertheless a welcome addition to the larder after a long sea-voyage, and recently the Swedish and other South Polar expeditions were forced for many months to subsist almost entirely on their flesh and eggs. It was persecution of this kind, it will be recalled, that led to the extermination of the Great Auk, and from all accounts the Penguins are becoming sadly depleted in many of their breeding grounds.

As regards size there is considerable range, from the Blue Penguin (Eudyptula minor) of Australia and New Zealand, which is only about sixteen inches in length, to the Emperor Penguin (Aptenodytes forsteri) of the shores of the Antarctic continent, which has a length of forty-eight inches and a weight, according to Ross, Nordenskiöld, and others, of sixty to seventy-eight pounds. The length of the various species is between sixteen and forty-eight inches, the average being about thirty inches.

That the Penguins represent a group of great antiquity is shown by the discovery of numerous fossil remains as well as by the apparently primitive character of certain structural elements. The oldest known fossil form (Palaeeudyptes antarcticus) is found in the Eocene of New Zealand, and according to Hector, was of gigantic size, standing between six and seven feet in height, although other authorities would make it no more than five feet. In any event it was considerably larger than the largest living species, and it had a proportionately longer wing, yet all of the important skeletal modifications had been already acquired. Within the past few years, thanks largely to the revival of Antarctic exploration, no less than thirty-one nominal fossil species belonging to nineteen genera have been described, of which number five genera and species were obtained by the Swedish South Polar Expedition on Seymour Island only about two degrees below the Antarctic Circle, and the remainder by Dr. Florentino Ameghino in Patagonia, all, it is believed, in beds of Miocene age.’ These remains have been studied by Drs. Wiman and Ameghino with the astonishing result of showing apparently that the earlier forms of Penguins, so far as shown by their limbs and especially by the tarsi, were much more generalized than the living species. The tarsi, while comparatively longer in the fossil species than in the living forms, had their component bones much less clearly indicated than in modern Penguins, which is exactly the opposite of what should prevail, if, as has been supposed, the tarsus of the living Penguin is a survival of the primitive free condition of these bones. In other words, it appears that the present-day Penguins, with their uniquely free tarsal bones, have been derived from forms in which these bones were more or less consolidated, which naturally brings them closer to ordinary carinate birds in which the tarsal bones are practically solid. This consolidation of the tarsal bones is possibly an adaptive feature which has perhaps been brought about ” by the habit of sitting with the tarsus on the ground when at rest.”

The relationship between the Penguins and other birds is rather hard to make out. Professor Watson, who studied the extensive material obtained by the Challenger expedition, regards them as the surviving members of a group that branched off early from the primitive “avian” stem, but “at the time of their separation the stem had diverged so far from reptiles as to possess true wings, though the metatarsal bones had not lost their distinctness and become pressed into the single bone so characteristic of existing birds.” Pycraft has studied the anatomy of the group more recently, and, while he recognizes the fact that the skeletal specialization has reached the high-water mark, it does not, he claims, take us beyond the confines of the Class. He says: “Osteologically the Penguins seem to be nearly related to the Tubinares and Pygopodes, and, as Gadow and others have shown, the evidence of the soft parts confirms this supposition.” Dr. Stejneger considers that the Penguins should be placed in a group of equal rank with the Ostriches and their allies, and the rest of living birds, that is to say that existing birds should be divided into three groups, of which the Penguins should constitute one. Others, and more especially Gadow, whom we are following, regard the characters as of somewhat less importance and would only accord them ordinal rank. Apparently we must look to paleontology for further light on this perplexing point, and this, as already pointed out, seems to indicate that the line separating them from carinate birds in general is less sharp than was formerly supposed.

Species. — About twenty living species of Penguins are known. They are confined exclusively, as already stated, to the Antarctic region, never crossing and rarely even approaching the equator. They are, perhaps, most abundant in species in the vicinity of the Falkland Islands, but they do not range north of Tristan da Cunha in the Atlantic or Amsterdam Island in the Indian Ocean, although they are common about New Zealand and the west shore of Australia, one species occasionally reaching as far north in the Pacific as the Galapagos Islands and another in the South Atlantic to the coasts of South and Southwest Africa. The causes governing their distribution within this area are not well understood, but apparently it does not depend wholly upon temperature, for at the most northern point reached by them the temperature of the sea is about 62°, and from this point they extend their range to water but little above the freezing point. They exhibit none of the tendencies to perform regular migrations, although they seem well enough fitted to undertake such journeys, and their distribution probably depends upon the food supply. The naturalists of the Challenger expedition did not observe them at any greater distance from land or ice than forty or fifty miles.

The six genera into which the Penguins are divided may be separated into two groups. In the first, which embraces only the genus Aptenodytes, both mandibles are long, relatively slender, and slightly curved downward at the tip, while in the second group the bill is of moderate length, and never has the lower mandible curved downward. To Aptenodytes belong the two largest species, the Emperor (A. forsteri) and the King Penguins (A. pennanti) respectively. The Emperor Penguin is bluish above and white below, with the top of the head, cheeks, chin, and throat deep black, while there is a large semi-circular patch of orange-yellow on each side of the head. The total length is about forty-eight inches and the distance between the tips of the flippers thirty-six and one half inches. They frequent the shores of the Antarctic continent. The King Penguin is much smaller, being only about twenty-six inches long and is similar in coloration to the other, except that the bluish gray of the upper parts inclines to pearl-gray on the back of the neck and shoulders, and the orange patches on the sides of the head continue as narrow bands down each side of the throat, and unite at the base of the fore neck, broaden into deep orange patches, which shade into yellow and disappear on the white breast and under parts. This species is found about the Straits of Magellan, Falkland, Marion, Kerguelen, Macquarie, and Stewart islands.

Somewhat closely allied to the above are the three species of Pygoscelis, of which perhaps the best known is the so-called ” Johnny” (P. Papua) of Kerguelen and the Falklands. About thirty inches in length, it has the upper parts slate-gray and the chest and under parts pure white, and with a broad white band across the crown between the eyes. Kidder found them nesting extensively on Kerguelen Island. When undisturbed the nesting sites were near the sea, but in other instances they were half a mile or more inland, and numerous very distinct paths have been worn by the successive generations, until in some cases they are as much as four feet in depth. As a rule two young were found to each old bird, and, he adds : “Singularly enough, one of these was always well grown, apparently from one to two months old, while the other had just been hatched or was still in the egg. It must, consequently, be the practice of these birds to rear two broods in a season, keeping both in the nest at the same time.” The other species are P. adeliae and P. antarctica, both without the white band across the crown.

Distinguished by a stouter bill and an eyebrow band of more or less elongated golden feathers, are the five or six species of Catarrhactes, or Rock-hoppers,as they are called from the habit of “hopping” rather than walking. The Kerguelen species (C. chrysocome) is about twenty-five inches in total length, dark slate above, with the top of the head black and the throat and belly white. The feathers of the crown and back of the head are elongated into a straggling crest three inches in length, while the stripes above the eyes are of golden yellow feathers quite three and one half inches long. Their nests, placed among the loose rocks, were lined with dried grass, and each contained two white eggs, “of which one is usually larger than the other.” “They were wonderfully courageous,” says Kidder, “erecting their sulphur-yellow plumes and trembling all over with excitement on my approach, while they kept up a strident cackling that was almost deafening.” The remaining species are separated mainly on minor differences in the crest; all range from Tierra del Fuego and the Falkland Islands to New Zealand.

The smallest of the Penguins are comprised in the genus Eudyptula, of which two species are known. Of these we may mention the little Blue Penguin (E. minor) of the coasts of South Australia, Tasmania, New Zealand, and the Chatham Islands. It is slate-blue above and pure white below, and is without streaks or crests on the head; its length is about sixteen inches. It breeds in large numbers on islands in Cook Strait and Bass’s Strait, and appears to take great pains in constructing paths and avenues through the breeding grounds, carefully removing all sticks, stones, and herbage. The other species (E. albosignata) is similar but slightly larger and has both outer and inner instead of only the inner margins of the “flipper” margined with white; it is confined to the coasts of New Zealand.

The remaining genus (Spheniscus) embraces four species, and may be known by the rather long, stout bill, the basal portion of which is furrowed by many longitudinal ridges; there is also a well-developed white eyebrow stripe. Of these the Cape Penguin (S. demersus) occurs on the coasts of South Africa, and the others about the coasts of South America, the Galapagos- and Falkland Islands.