Part 4

SUBLEASES The snug, secure cavity that a woodpecker chisels in some tree trunk for its nest will last for many years, a shelter in which tree swallows, house wrens, screech owls, bluebirds, or wood mice may make headquarters and use as a nursery. In the strange forests of saguaro, a giant cactus of southern Arizona, the nest cavities of the gila woodpeckers and the gilded flickers in the cactus trunks seem necessary for the presence of many nesting birds. Without them the birds would have to go elsewhere for cavities in which to nest. In old woodpecker nest cavities the elf owl, pigmy owl, screech owl, sparrow hawk, ash-throated flycatcher, martin, and crested flycatcher commonly nest, and cactus wrens and even Lucy's warbler may use them. Their use is not confined to birds alone, for scaly lizards, snakes, rats, and mice have been found in them. In the Argentine there is a woodhewer that appears to depend on the domed mud nest of the red oven-bird for its nesting sites. It takes over a recently vacated or an old nest of the oven-bird and lines it with grass and feathers for its own use. In Africa and Madagascar the great domed nest of the hammerkop stork may find a secondary use in sheltering barn owls.

SANDPIPERS AND EAGLES But it is not only burrows and domed nests that when deserted by their original occupants are used by other birds. The solitary sandpiper of our northlands belongs to a group in which nest building is reduced to a minimum, usually little more than a hollow in the ground with a few bits of material added. But the solitary sandpiper, and the green sandpiper of the Old World have broken with tradition and customarily lay their eggs in the abandoned nest of some thrush. Our great homed owl is another bird that may use the discarded nest of a crow or hawk for its eggs and young. And age in the eagle's nest means little to the eagle. Frances Herrick, the noted chronicler of the life of the American bald eagle, writes of one nest in the crotch of a lofty tree that had been in use for thirty-six years. Each year more material was added until the nest became 12 feet high, 8½ feet across the top, and was estimated to weigh 2 tons.

Man has found, among others, the following two direct uses for two kinds of birds' nests: one he uses for food; of another he makes covering for himself.

The swift's nests used for food have been discussed in another chapter, "Birds' Nests and Their Soup," so here I will only tell of the use of birds' nests as human covering.

EIDER-DOWN BLANKETS An eider-down has come to mean a comforter, a sleeping bag, or even a padded jacket. But to an ornithologist eider down still has its older meaning: the down of an eider duck. It is this material gathered from the eider ducks' nests which forms the article of commerce. The eider's nest may contain grass, seaweed, and sticks, but it is notable for the blanket of down on which the eggs rest, and with which the female covers the eggs when she leaves them. This down is plucked from the breast of the female. If it is taken from the nest she replaces it with more, and it is on this principle that harvesting of the down is carried out. On islands and islets in the northern part of the North Atlantic eiders nest in great numbers in dense colonies. Some of these are jealously guarded by the local inhabitants, who gather the first blanket of down from the eggs, and later, after the eggs have hatched, gather the second crop of down with which the female has replaced the first to guard her eggs against the inclement weather of those boreal latitudes. Each nest may yield an ounce or so of the precious down, which is carefully cleaned and sent to market. It is this material, extremely light, extremely elastic, and one of the best non-conductors of heat, which finally becomes the important part of real eider-down comforters, sleeping bags, and padded jackets.

SYMBIOSIS--ANIMALS LIVING IN MIXED HOUSEHOLDS

Symbiosis, a term from the Greek, is what the biologist uses for the living together of two dissimilar organisms. In a broad sense it includes such diverse relations as the lice living on man and rats in his house, the union of an alga and a fungus to form a lichen, and the cross-pollination of flowers by hummingbirds.

The story of the burrowing owls of our Western plains living in amity with prairie dogs and rattlesnakes as one happy family comes to mind as an example. But "foolish nonsense" is how the noted biographer of North American birds, A. C. Bent, characterizes such stories. He then goes on to quote evidence as to what actually happens, and one can see how the story originated. The prairie dogs, which are really plump, dumpy, ground squirrels and not dogs at all, dig their burrows close to each other on the prairie in colonies which have come to be called prairie-dog towns, or dog towns or simply "towns." Burrowing owls also take up their residence in these towns, probably because they find burrows ready made and do not have to dig their own as they are quite able to do.

MODERATELY PREDATORY The owls may make an occasional meal of a young prairie dog, and a prairie dog may perhaps dine occasionally on owl eggs, but on the whole owls and dogs get along on terms of easy familiarity. Sometimes when alarmed, both may scuttle into the same burrow for safety, but each has its own burrow. With the rattlesnake it is different. The rattlesnake may live in burrows in the dog town, but when it is hungry it eats owl or dog as occasion offers. While the picture of a happy family of owl, dog, and snake is a myth, the symbiosis of owl and dog, at least in the same colony, is striking.

In Africa there is a tiny falcon only about eight inches long which is called a pygmy falcon because of its small size. When Dr. Friedmann was studying the social weavers in South Africa, birds which nest in large colonies under a common roof they make in a savanna tree, he found these falcons occupying nest chambers in thriving weaver colonies. There was no friction between the weaverbirds and the falcons, and they were sometimes seen to sit side by side. When Friedmann collected three of these falcons he found bird remains in their stomachs but they were not remains of the social weavers. Apparently the falcons were feeding largely on small birds, but they did not molest the weaverbirds which had made the nests the falcons were using.

PARROT-DUCK-OPOSSUM MÉNAGE We occasionally find a mallard nesting in a tree, on an old crow or hawk nest, and there are ducks like the wood duck and the golden-eye, which usually nest in holes in trees, but a South American duck called the tree teal habitually nests in a parrot's nest. The parrots, called monk parakeets, make their nests in compact colonies in the branches of trees, so close together that they form a single mass. The tree teal's usual manner of nesting is to lay its eggs in one of the chambers in this apartment-house colony. At first the eggs are laid on the rough twig floor of the nest, but as the eggs increase in number a lining of down, plucked from the breast of the bird, is added until it may even extend out the entrance of the nest. Apparently parrot and duck both get along amicably in their pendant treetop cradles. An opossum sometimes also finds these parrot nests to its liking, though one wonders if it may not have a meal of young parrot or duck in mind. But be that as it may, in different chambers of a single communal nest of these parrots, parrots, a duck, and an opossum have been found.

On islets off the New Zealand coast lives a rather large-sized lizard called _Sphenodon_. It's rather well known by name, at least, for it is one of those relics of a formerly more widespread group which are called living fossils. It is also noted for its remarkable development of a pineal eye, the remnant of an important sense organ in ancestral forms, and formerly an organ some philosophers supposed to be the seat of the soul. But here we are interested in the fact that petrels swarm to these same islands to dig their burrows and lay their eggs in them, and it is in these same burrows that _Sphenodon_ spends its daylight hours. Apparently the insect-eating _Sphenodon_ and the oceanic-feeding petrels share the burrows amicably, adding still another example of a rather long list of dissimilar organisms whose lives are associated.

BIRD APARTMENT HOUSES

Every now and then in our press appear blasts against crowded living conditions in our cities, and the tenements where people are crowded together. Often there is the implication that this type of thing is unnatural and abnormal. And yet when we look about us in the bird world we see that gregariousness is a common trait. We have only to remember the great flocks of starlings and blackbirds in the autumn, or the massed flights of water fowl. Not only in traveling and in feeding, but also at nesting time birds may gather together, and some birds nest in such close association that the term "apartment houses" or "tenement" is really applicable.

The martins' house on our lawn with perhaps dozens of closely spaced rooms (some houses have as many as two hundred rooms) is a case in point. The neat martin house, made of boards, is a man-made thing, but even before the white man came to this continent, and before the Choctaw Indians hung up groups of hollow gourds for the martin colonies to use, the martins nested in colonies. Even in recent years certain colonies we might consider unprogressive have been reported as using such diverse nesting situations as among the boulders of a lake shore in Minnesota, and the closely spaced woodpecker holes which riddled a dead pine in Florida. And probably it was always thus. The martins liked company at nesting.

CLIFF DWELLERS, TOO Perhaps it would not be proper to consider a colony of bank swallows, each with a separate burrow in the same small cut bank and roofed with the same few square yards of turf of mother earth, as a real apartment house of cliff dwellers. But the term has been used in connection with a West Indian woodpecker, where a dozen pairs were nesting in a single dead tree, and "the trunk was a veritable apartment house." A similar situation exists with the naked-faced barbet of West Africa. This bird too makes a hole in a dead tree for its nest, like a woodpecker, and colonies of thirty to fifty birds may be found nesting in a single dead tree, while other dead trees nearby, apparently equally suitable, are untenanted. Colonies of hundreds of nests of cliff swallows, the nests touching and overlapping, may be under the eaves of a single barn, or as they used to be and some still are, on the sheltered side of a cliff. But as these birds had nothing to do with the making of the roof, perhaps these too do not deserve to be rated as apartment houses.

In southern South America there is a monk parakeet that makes a real tenement. It nests colonially in treetops, and the nests of sticks are placed so close together that they merge and form a single mass, up to nine feet across, in which each parakeet has its own nest. Similar to this is the palm chat. This West Indian bird is small and thrush-sized, dull in color, brownish with a streaked breast, nothing remarkable to look at, but it carries amazingly large sticks, little thinner than a lead pencil and as much as two feet and more long up to the top of a palm tree, and there it makes its bulky community nest.

BUILD NESTS CO-OPERATIVELY These stick nests, which may be four feet and more across, are conspicuous and regular features of the landscape in Hispaniola. The colony consists of four to eight pairs of birds, and each has its own apartment in the bulky structure, and its own passageway to the outside. But in the parts of the community nests that hold the individual nests together and cover them there are roughly defined passages running through the interlacing twigs of the top of the nest so that the birds can creep about under cover. Apparently some of the work is carried on in common, for as many as half a dozen birds may be working close together, pulling and twisting twigs more firmly into place.

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.