Part 7

The social weaver is the most advanced apartment builder. It, like the palm chat, has little of distinction in its appearance, being mostly dull brownish with a black face. But in its home country, the savannas of Rhodesia in southeastern Africa, its huge community nests in the savanna trees may be seen from afar. The largest Friedmann saw when he was studying the bird there was about 25 feet by 15 feet, by 5 feet high, and contained about 95 nests. And this might have been still bigger, for part of it had broken the branch on which it rested and fallen to the ground. Sir Andrew Smith, the early ornithologist of South Africa, has written that when these birds start a colony they first of all make a roof of coarse grass. The group to which the social weaver belongs gets its name from the remarkable ability some of them have of weaving their nesting materials. But the social weaver neither plaits nor weaves its roof. It puts the roof together in the form of a well-made hayrick with a fairly definite thatching arrangement so that the water runs off. This is a community effort. Under this roof each individual pair makes its own separate nest. These apartment houses are used year after year, but last year's chambers are not used, new ones being made under the roof each year, and so it grows bigger and bigger until the weight of the mass may break the branches and cause a part or the whole to fall to the ground.

BIRD HELPERS AT NESTING TIME

In many a well-run American home the children have definite responsibilities, the older children may help look after the younger, and even grown-up relatives may stay as part of the family group. As in so many cases there may be found parallels to this in the bird world.

The ani, the curious tropical American cuckoo that makes communal nests, is gregarious and the young of the first brood become part of the parent flock. Two more broods may be raised during one season in Cuba, and the young of the earlier brood may feed their younger brothers and sisters of the later brood. The same has been recorded for many other species in the wild: in eastern bluebirds, mountain bluebirds, wheatears, long-tailed titmice, barn swallows, coots, rails, and gallinules young have been recorded as feeding still younger birds. In captivity this habit has been seen a number of times. Young birds hardly able to feed themselves may help feed still younger individuals of the same or other species, and a nestling crowned hornbill has been seen to offer food to its nestmates. This tendency to feed nestmates evidently appears very early in the life of the bird, as Dr. C. O. Whitman, who worked intensively with pigeons at the University of Chicago, recorded a hybrid dove only twelve days old that fed its nestmate.

FIVE JAYS AT A NEST It was rather generally known that occasionally more than the two parent birds attended a nest, but until 1935, when Alexander Skutch, the authority on the biology of Central American birds, published his paper "Helpers at the Nest," few of us realized how widespread this was. Since most birds of a species are difficult to identify individually, one must actually see the extra, unmated helpers at the nest along with the parents to be sure they are there. In the brown jays of Central America that Skutch studied closely the colors of the soft parts, bill, feet, and eye rings were variable and he was able to recognize many individual birds. At five nests he watched he found at least one helper at each nest, and at one there were five helpers, all bringing food. Sometimes, if between an incoming, food-laden bird and the young, they would take the food and pass it on to the nestling. At one nest the unmated helper was more zealous in guarding the nest than were the rightful parents. Sometimes, perhaps, these helpers were unmated young of the parents' previous year's brood, but this could hardly have been the case where there were five helpers, for the brown jay ordinarily raises no more than three young a year. A black-eared bush tit of Central America seems to have a great preponderance of males and at one nest in addition to the parents there were three other males bringing food to the young.

MATERNAL PENGUINS Perhaps the most striking example among birds is the emperor penguin. These birds breed in the dark and cold of the antarctic winter, on the edge of the ice shelf. The single egg is carried on the feet of the brooding bird; indeed one wonders what other adaptation for holding the egg would be possible in this land of ice, snow, and water. Only a few of the adults in each colony lay eggs any year, perhaps one in five, or one in twelve. But all the adults in the colony have the urge to incubate and brood. Thus many old birds, rather than merely the two parents, may take turns caring for each egg or chick, leaving the rest ample time to feed. So strong is the urge to brood that struggles may take place over a chick and it may be very roughly handled. Indeed the chicks may so resent this that they may creep away into ice crevices and freeze to death. Another strange turn this behavior may take is that frozen eggs, dead chicks, and even bumps of ice of suitable size are carried on the feet and covered with the birds' feathers by their "would-be fathers and mothers."

A NAME FOR A BOAT

A request for the name of a sea bird, a name to be used for a boat, came to me at my desk in the museum one day. My memory was quickly exhausted with sea gull, sea swallow, and albatross. But I keep within reach the handy guide, Birds of the Ocean, by W. B. Alexander. In the index I found twenty pages of names, two columns to a page. They started with aalge, Uria, and went on down through the alphabet to yelkouan, Puffinus, and to zimmermanni, Sterna.

EUPHONY NEEDED A name should be short, pleasant-sounding, and easy to remember and to say, so obviously such words as Macronectes, Brachyramphus, Aptenodytes, and Coprotheres are ruled out among the scientific names. But further, when choosing a name for a boat from among those of water birds, one should consider the kind of a boat. There should be some appropriateness; some points of resemblance between the boat and the bird, or between the boat owner and the bird. Albatross seems right for a seagoing sailing ship, sailing to southern oceans; tern (or sea swallow) appropriate for light, dainty coastal sailing craft; puffin or auk or murre for power craft, for these birds spend most of their time stolidly on the water and when they fly have a direct buzzing flight. Loon and dabchick would do well for fresh-water boats. But one objection to both them and the various auks for a name is that these birds spend much time swimming underwater. They might better give their names to submarines. The big, stocky sea ducks, called scoters and eiders might suit some stout craft that ply to arctic waters.

SCIENTIFIC NAMES AVAILABLE I reviewed the host of other names. Scientific names need not be ignored either. What is nicer than Gygis, the name of the white, fairy, or love tern of the South Seas for a small summer sail boat? Then going farther afield into austral waters for far traveling craft there's Diomedea, the name of the albatross, and Daption, the medium-sized petrel that also is called pintado for the same reason a white-splashed horse is called a pinto, and Prion, the tiny whalebirds of the antarctic whose blue-gray back is near the ideal ocean-camouflage color. Larus, a good honest name without frills, belonging to the gulls that haunt our harbors, coasts, and lakes, would do for a plain, everyday sort of boat. Kittiwake is another gull that spends more time at sea. Gannets are boldly black and white, strong-flying birds of the North Atlantic, and one could use that, or its scientific equivalent, Moris, for a boat.

Penguin and pelican I'm doubtful about; I can't imagine a boat for either. Skua or jaeger would, of course, be a lovely symbol for a pirate vessel, as would frigate bird; both are birds that practice the stand-and-deliver method of getting food from weaker fisherfolk. The petrels called shearwaters are among the hardiest seagoing birds, but the name has little association for most people beyond wondering if they feed around breakwaters. Petrel itself isn't a bad name, though one might think of the storm petrels, which are also called Mother Carey's chickens, and have been considered the souls of drowned sailors, though their name perhaps refers to Peter, and his attempt to walk on the water, as these birds are continually trying to do.

Phalaropes are snipes of sorts that have taken up a periodic seagoing habit, and their name might often be appropriate. Even their habit of spinning quickly about as they sit on the water might still agree. A Chicago man named his Chris-Craft Sandpiper, after, as he said, the bird that goes hopping along the beach before the waves.

Sula is a good sort of a word, and the name of birds that are strong, swift fliers of the tropics. But in English they're usually called booby, which is an English word meaning simpleton (which name the birds got from stupidly perching on ships). Alle for the little auk or dovekie would do for a tiny boat in northern waters, and I knew of one boat called the Alca, after the razor-billed auk, while Cepphus, the name of the black guillemots, is equally good, as is both Lunda and its equivalent puffin.

Some names have a stark simplicity that would attract few, like shag, used for the cormorant, and muttonbird for a petrel. The cahow people might shy from because for many years we were not sure whether this West Indian petrel was extinct or not.

Myself, there are two names I rather like and I've been saving for the last: for a small sailboat I'd say the Wideawake, as the sooty tern is called in its tropical home, and the other, for a larger seagoing boat, is the Mollymawk, a sailor's name for the albatross.

WEAVERS AND TAILORS IN THE BIRD WORLD

One can imagine the consternation in trade-union circles when it becomes known that there are, among birds, those who weave and those who sew. Their products are entirely for home consumption and there are no minimum wage, no maximum hours, or any fair-trade or quality agreements. None of the Audubon societies have even touched on the matter.

WEAVING The sewing and the weaving is done entirely in the construction of nests. To take up the weavers first, we can point to the Baltimore oriole, which makes a sac-shaped, pendant nest, often hung from the trailing tips of elm branches. The walls of this sac are formed of fibers pushed and pulled back and forth with the birds' bills in a seeming haphazard way so that a roughly woven or stitched fabric results. But the finest weavers belong to that group of birds known as weaverbirds. One might expect that to be an expert weaver a bird would have to have a slender bill. But no, their bills are short, stout, clumsy-looking, and sparrowlike. And yet these are the birds that weave elaborate pendant nests of fibers and straws. The finest are in shape like an inverted retort, with the nest proper in an oval chamber, fastened to a branch by a special strand of fibers, and with a tube or funnel for an entrance. The walls of these fine weaverbirds' nests are amazingly strongly and neatly woven. In captivity one of the weaverbirds, the red-billed weaver, was studied at its nest building and it was found that the strong, intricate, and beautiful weaving of this species actually included knots of several sorts.

TAILORING The tailoring is done by birds of quite another group. They are Old World warblers of several sorts, some in southern Asia and some in Africa. The tailoring consists of sewing the edges of leaves together to form a place for their tiny nests. The Indian tailorbird is perhaps the best known. When these tiny olive-green and gray birds set about nest building the female punctures the margins of the leaves with her bill. Then she brings cobwebs and pushes them through the punctures in the edges of the leaves, and winds them around, and draws the edges of the leaves together. Strands of cotton are used too for this. Sometimes a single leaf is used; its two edges being drawn together to form a funnel. Sometimes a number of leaves are joined. Sometimes it is claimed knots are used, but this seems not to be the case. What are mistaken for knots seem made in this way: The cotton used is soft and frays easily, so that the part of it forced through a tiny aperture issues as a fluffy knob, which looks like a knot. "The bird makes no knots; she merely forces a portion of the cotton strand through a puncture," and the edges of the puncture catch and hold it, according to Casey Wood, who studied the birds in India. The lining of the nest is of soft material and this the bird anchors by making a puncture in the leaf, grasping a strand of this material, and pulling it out; the cotton outside then expands into a minute button which helps hold the nest and contents in place as though riveted. One nest is recorded as having been so riveted in seventy-five places.

The camouflage of the tailorbirds' nests is very good; it is usually built in thick foliage, the leaves are little deranged, the punctures do not cause the leaf to die; and the leaves being the same as the others, there is little for the eye to pick up as indicating a bird's nest.

SOCIAL PARASITES AMONG BIRDS

The mother who would leave her infant on a stranger's doorstep, to be brought up an orphan, not even knowing its own parents, is a despicable character in human society. But when we leave the man-made society we must leave man-made rules of behavior and man-made prejudices behind. Morals are human. The rest of the animal world is not immoral, it is amoral. It cannot afford criteria beyond survival and reproduction. So while we call certain birds "social parasites," we attach no stigma to them. They represent several groups: the cowbirds, the weavers, the cuckoos, the honey-guides, and the ducks.

Carelessness in egg laying is common even in birds that ordinarily lay their eggs in their own nest and care for them themselves, as for instance the robins' eggs that you may find on your lawn (which of course are wasted; addling and rotting). Perhaps the fate of the eggs of pheasants and ruffed grouse which are found in the same nest may be more happy. Ducks usually make their own nests, but many species occasionally lay eggs in the nest of another species, and one South American duck no longer makes any nest of its own, but is a social parasite, not only on other kinds of ducks, but also on coots and some other birds.

The small, well-marked family of honey-guides of Africa, notable in other ways, also is remarkable for being social parasites. Their favorite host species, chosen to look after the eggs and young, are their close relatives, the barbets (which themselves are most closely related to our woodpeckers).

The nesting of certain African weaverbirds was long a puzzle to ornithologists until it was found they too were social parasites, on other weaverbirds.

VARIED NESTING HABITS The cowbirds, of several species in North and South America, belong to a family notable for the variation in its nesting habits. Their nests vary from the elaborate purse-shaped structures of the oropendola and orioles to the dome-shaped nest on the ground of the meadow lark, the simple cup of the bobolink and redwing; the cowbird makes none. The cowbird lays its eggs in the nests of a wide variety of other species to be cared for by them. Here those who discuss the relative importance of heredity versus environment can profit by considering these social parasites. The young cowbird, hatched and brought up by, say, a yellow warbler, remains a cowbird. As soon as it no longer needs its foster parents' care it flocks with other cowbirds, with all their mannerisms and characteristics, and next season it mates with another cowbird. There is nothing left of its early environment.

The cuckoos of the New World and some of those of the Old make their own nests in normal avian fashion. But a number of Old World species are social parasites, and their behavior has long been a subject of study and discussion. Specializations indicate that here perhaps we have the highest stages of social parasitism. Whereas the cowbird may grow up with nestmates that are the young of the foster parent, unless perchance it crowds them out or starves them if it is larger, the young cuckoo gets the rightful occupants of the nest on its back and throws them out of the nest to perish.

EGGS LOOK ALIKE Another refinement in social parasitism by the European cuckoo is that apparently certain individuals, and apparently certain strains, lay their eggs only in the nests of certain host species. And these cuckoos' eggs resemble those of the particular species in whose nest the cuckoos' eggs are laid. For example, if certain cuckoos lay their eggs only in the nests of meadow pipits these cuckoos' eggs would resemble those of meadow pipits, while another group of cuckoos specializing in hedge-sparrows would have eggs resembling those of hedge-sparrows. Another oriental cuckoo has a color adaptation in the young. In southern Asia these cuckoos parasitize crows, and the nestling cuckoos have black feathers like the young crows; in the Australian area where the same species of cuckoo occurs it parasitizes grayish-brown honey eaters and the young are brown, more like the rightful nestlings. Both these resemblances apparently reduce the chances of the cuckoos' offspring being rejected by the foster parents.