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 [Ref]
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 [Ref]
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.
FISH EATS BIRD! [Ref]
It has become commonplace to hear about birds eating fish. The government gets out reports on the relation of fish-eating birds to fish abundance. The cries of commercial fisheries have caused inquiries to be instituted into the food of cormorants that were supposed to be eating the fish before they grew up enough for us to eat. The scarcity of salmon in some of our Northeastern streams has caused the allocation of biologists to study the predation of kingfisher and merganser on salmon fry and fingerlings.
But fish get some of their own back by eating birds. It's not as spot news as the "man bites dog" angle, but it's certainly less widely known.
To one who has fished for large-mouth black bass among the cypress trees and the bonnets of water hyacinth, and seen the bass strike savagely at surface lures as soon as they hit the surface, it comes as no surprise to find they strike at, and catch, such birds as Maryland yellow-throats that flutter across close to the surface of the water.
Young ducks, too, are good game to the large-mouth, and probably many a young duck finds its way into the maw of a bass. On a pond where bass had taken many young ducks I heard a story of a fisherman who made a floating model of a mother duck, powered it with a propeller, and attached to it by lines of various lengths several floating models of downy ducklings. In each duckling was concealed a hook. The whole flotilla was set afloat, and drifted across the pond. Mother steamed ahead, with young following. Soon the bass, used to a duck diet, began to grab the ducklings. When the model was retrieved several large bass were taken.
In Northern waters, where Northern pike, or jackfish, as they're called in the North, abound in duck-nesting waters, pike are accused of eating enough ducklings to affect the survival of the broods. Many a marshland traveler has reported young ducks and young grebes diving, to be seen no more. He's blamed the pike. Sometimes perhaps the young bird has simply come up unobserved. But enough pike's stomachs have proved to have young ducks in them to demonstrate pike do eat ducklings. Strangely, in some areas, pike eat many ducklings; in others they do not eat them. But it's not alone young birds or small birds that get eaten by fish.
A twenty-four-inch bass is recorded as having been caught while it still had the legs of a full-grown coot projecting from its mouth. From beak to tip of its outstretched legs the coot measured seventeen inches and it weighed one and one quarter pounds.
Angler fish weighing between forty and fifty pounds have been found to have eaten birds. One had the band from a Manx shearwater in its stomach, and another had an adult American merganser. In tropical and subtropical seas the examination of birds seemed to indicate they had been attacked by some fish and seized by the feet, but were able to escape, and a white-winged black tern off Corsica has been seen to disappear under the water, presumably dragged under by a fish.
CROWS ARE SMARTER THAN "WISE" OWLS [Ref]
The owl has always been considered the symbol of wisdom. The old saying has it that "fine feathers don't make fine birds," but I'm afraid that the owl has taken in people with its appearance. The owl's reputation for wisdom seems to be based on a staid, impressive appearance combined with an inarticulate disposition. Though owls do at times make a great deal of noise, hooting, shrieking, and whistling, much of the time the owl sits quietly looking wise and saying nothing. But owls don't seem to have much behind the front they put up. People who have studied them find the young are very slow to learn to feed themselves, and one saw-whet owl that was kept captive refused to eat liver put into its cage, apparently not recognizing the meat as food. But when the liver was stuffed into an empty mouse skin the owl at once ate it. One might conclude that the owl was the original "stuffed shirt."
The crows and their relative, the jays, are the birds that are really intelligent. They are active and usually have little trouble getting enough to eat. They have an abounding curiosity that leads them to spend their time investigating things and getting new experiences. And they seem to profit by these experiences, too.
The following is how three ravens co-operated in getting a bone from a dog, as written by B. J. Bretherton:
"He was espied by a raven who flew down and tried to scare the dog by loud cawing, in which he was shortly afterwards assisted by another, both birds sidling up to the dogs head until they were barely out of his reach. Just at this time a third raven appeared on the scene and surveyed the situation from an adjacent fence, but soon flew down behind the dog and advanced until within reach of his tail, which he seized so roughly that the dog turned for an instant to snap at him, and at the same moment the bone was snatched away by one of the ravens at his head."
CROWS LEARN FROM OTHERS Crows have been recorded as profiting by the experience of one of their numbers. In Washington, when almonds were ripening in the almond orchards and crows were swarming there threatening to destroy the nut crop, an estimated 30,000 crows were involved and the destruction of an $800 crop was complete in two days. Various methods of control were tried unsuccessfully. Finally some almonds were slit open, poisoned, and scattered about in the orchards. Very few crows were actually poisoned, not exceeding 1 per cent of the flock. The first reaction of the crows when one of their number was poisoned was one of extreme panic. There was tumultuous clamoring and confusion. Then the flock abandoned the attempts to feed on almonds and left the area completely. Here we have a case of superior intelligence, birds profiting by the sight of a few of their numbers being poisoned fleeing the area and so escaping being poisoned themselves.
TAME WILD BIRDS [Ref]
We think of wild birds as being shy creatures by nature. For those of us who have kept a feeding station for birds in the winter so as to have the pleasure of association with the chickadee, nuthatches, woodpeckers, and other visitors, one of the most attractive things is that the wild birds become tame. Through association with persons they gradually learn that human beings are not to be feared. The high point of many a bird lover's experience is when a chickadee becomes so tame that it will perch on his body and without fear will feed from his hand.
It seems to be true that birds in wilderness areas are wilder and more shy of men than those living about dwellings where they are protected. This is notably true of the robin. In villages they hop around on the ground unmindful of the near presence of humans. How different they are in the wilderness, where the robins fly away apparently in great fear, while the human intruder is still far distant.
It comes as a considerable surprise to find that here and there over the world there are instances of birds with so little fear of humans that they come and perch on them.
PERCHING ON PEOPLE In the Galápagos Islands, where the general fearlessness of birds is famous, one of these cases is recorded. David Lack, who was studying the biology of the Galápagos Islands' birds, found when walking through the woods on Indefatigable Island that a flycatcher would sometimes try to settle on his head. Lack stood still and found the bird's object was to pull out some of his hair. The bird, having failed to detach any of the hair of his head, tried, apparently with no better success, to pull out hair from his eyebrows and then from his chest. This was at the height of the breeding season and apparently the bird was trying to get nesting material. This seemed to be a usual type of behavior there, and Lack correlated it with the general tameness of the birds on the islands.
There is a honey eater in Australia that includes in its pattern of behavior perching on people's heads and shoulders and attempting to pull out hair for use in its nest. A. H. Chisholm writes of going to certain places and taking companions with him for the sake of experiencing this, and the practice is so common with the species that Australians refer to this honey eater as "the hair dresser." In this case it is not tameness alone. The white-eared honey eater, which indulges in this practice, is no more tame most of the time than any of the other small local birds that live in that part of Australia. Only at nesting time does it attempt to light on persons. Chisholm correlates this hair-plucking trait with other habits of the honey eater: he speaks of its gathering hair from such animals as rock wallabies and gathering bristles from farmyard pigs and goats.
Our familiar phoebe has been recorded as perching on deer hunters in the fall and using them as a vantage point from which to conduct its hunting. This was in North Carolina, and the weather being warm, mosquitoes were notably in evidence. The bird showed no sign of fear or nervousness, but perched on the hunter's gun, on top of his head, and various parts of his body, and then flew out and picked up mosquitoes. As the hunter's face seemed to be attracting more mosquitoes the phoebe directed his attentions there. In picking mosquitoes off his face the sharp points of the bird's bill were noticeably felt at every capture and the irritation caused by a succession of these pricks caused the hunter to decide that he could take care of the mosquito situation better without the help of the phoebe. As H. H. Brimley, the hunter, put it "... my face was beginning to feel somewhat inflamed from the frequent pecks to which it had been subjected so I called it a day and told the phoebe to stop pestering me." This took place in a wild part of North Carolina and Brimley suggested that the phoebe's abnormal lack of fear was caused by its having never seen a human being before.
BIRDS AS PILFERERS [Ref]
Pilfering, or petty theft, is one of the less desirable but very human attributes of our race. But it's also pretty widespread in the animal kingdom. Theft as the usual thing is practiced by only a few birds. But when it's a case of petty theft, happening now and then, it is common enough in the bird world. It's not restricted to any group of birds, but may crop up almost anywhere. There's no threat or fight about it usually. The bird, which gets its food by means of the acuity of its vision and the quick co-ordination of its movements with the recognition of its food, sees the food in another bird's possession and just goes up and takes it. Sometimes the food is taken from a larger and stronger bird, an achievement accomplished by audacity, agility, and quickness. A sparrow hawk, that inoffensive little rufous-red falcon that spends most of its time catching grasshoppers, was sitting on a telephone wire holding a small mammal it had caught, apparently about to devour it, when a loggerhead shrike sitting nearby flew straight to the hawk, seized its prey, and made off, leaving the hawk sitting there, apparently dumfounded by the audacity and success of the attack. A case in which the pilfering caused a mild fuss involved an English kingfisher and a dipper. The kingfisher lit above a pool where a dipper was feeding, obtaining food in the pool and bringing it ashore to eat it. When the dipper next came ashore the kingfisher flew down, there was a momentary scuffle, and the dipper departed, leaving its food to the kingfisher, who promptly ate it. Despite this occurrence the dipper allowed itself to lose its prey again before it left, and the kingfisher presumably had to resume fishing for itself.
THEFT NOT RESENTED It is sometimes surprising that this pilfering, when it occurs over and over again, is not actively resented, particularly when the pilferer is a smaller bird. Some of the thrushes are especially docile when they're victimized. Sometimes when American robins are feeding on the ground, house sparrows hop along with them, and when the robin finds a worm the sparrow hops up quietly and boldly takes the worm from the robin with scarcely a protest from the victim. One robin is reported to have been robbed six times, of six worms, one right after the other by a small flock of sparrows while the robin continued to hunt for worms.
The starling, an aggressive Old World species introduced and very successful here, also victimizes the American robin. In one case a starling made four successful raids in five minutes, the robin not attempting to fight or defend its food, but simply moving off a little way and continuing to hunt for worms while the starling waited nearby.
This is not a new trait of the starling, for in its Old World home, in Britain, it has been seen to victimize blackbirds and song thrushes (relatives of our robin). This happened when a blackbird pulled up a worm, a starling flew to the spot, and the blackbird moved away, leaving the worm to the starling. This method of obtaining worms was sometimes used by all the starlings on a lawn where both species were feeding, much to the hindrance in the feeding of both blackbirds and song thrushes.
Gulls have been recorded as snatching fish from mergansers that had caught fish by underwater dives and brought them to the surface to eat. Gulls also follow pelicans, and just after the pelican has completed its plunge and before it can swallow the fish protruding from its bill, a gull may flutter in, alight on the water or even on the pelican's head, and seize the fish. The pelican does not attempt to do anything about it, but accepts the pilfering with stoic calm.
Grackles victimizing ibises seems perhaps the strangest of the whole series of reports. The ibis often attempts to elude the grackles but without success. About Lake Okeechobee, Florida, where ibis are common, they feed largely on crayfish, which they secure by probing the holes made by these creatures. Grackles swarm there, and, on occasion, no sooner does an ibis seize a crayfish than one to four grackles try to secure it. The ibis may take flight and attempt to escape with its prey, but one of the grackles usually gets the crayfish away from it.
Possibly some of these birds are on their way to becoming habitual pilferers, in which such social parasitism is a fixed mode of life. With evolution, if this thieving benefits the species that snatch the food, it may become a usual habit. For habits, like structures, are subject to variations, to selection, and thus to change and elaboration.
HIBERNATION IN BIRDS [Ref]
Not until 1948 did the scientific world have satisfactory evidence that any bird hibernated. True, it was an established fact that sometimes in cold weather some birds, notably swifts and hummingbirds, might become torpid for a short time, but this was not hibernation.
The early literature, of more than a century ago, contained many accounts, some claiming to be firsthand, of birds hibernating. Swallows in particular were reported as seen to submerge in ponds in the autumn. Numbers of them were said to have been found hanging to submerged willow branches apparently sleeping the winter away. When ponds were drained in winter, sometimes swallows were said to have been found buried in the mud, revived, and upon occasion kept alive indoors until the spring. Sometimes slime-covered swallows, evidently just out of hibernation, were reported found in the spring. Swallows were the most commonly recorded, but other species, too, were mentioned as hibernating, such as the cuckoo that shed its feathers and crept into a crevice to sleep away the winter.
Such accounts gradually disappeared from the literature. We can accept none of them. The old records of underwater and also the featherless hibernation of birds must be discarded. The occasional torpidity, in cold weather, of swallows, swifts, and hummingbirds is another matter, and appears to be of sporadic though not common occurrence.
FROGS MISTAKEN FOR BIRDS It is interesting to speculate as to how the old "firsthand" accounts originated. They had certain basis of fact. The first was that swallows were seen flying about in summer. They disappeared in winter. Aristotle claimed they hibernated, in a featherless condition, so there was nothing unusual in seeing them that way. Observation was less critical, and it is probable that frogs from the mud of ponds were mistaken for naked swallows, and perhaps bats, which do hibernate, taken from caves or hollow trees, were also mistaken for swallows.
AN AUTHENTIC RECORD In 1948, and again in 1949, Edmund C. Jaeger, of California, published accounts of a poor-will he found hibernating. This was the first acceptable evidence that such a thing occurs. In a little cavity in the wall of a canyon in the Chuckawalla Mountains of the Colorado desert in California, Jaeger found a poor-will in a state of profound torpidity in December, 1946. He could pick out the bird in his hand, examine it and put it back in the little cavity it occupied without eliciting more than a slight movement of its eyelids. On a later occasion handling it revived it somewhat.
The next winter Jaeger found a poor-will, perhaps the same bird, hibernating in the same niche. Over a period of eighty days, from November 26, 1947, to February 14, 1948, he visited it periodically, examined it, and took its temperature. The body temperature was low, 64°-68° F., compared with more than 100° F. of an active bird; with a medical stethoscope he could detect no heartbeat, and a cold metal mirror held directly in front of its nostrils collected no moisture from its breathing. The body processes were evidently very low. The bird was banded for identification, and in the third winter the same bird wearing the same band was found to have returned to hibernate again in the same rock niche. But on subsequent visits it was missing—perhaps having lived out its allotted span, perhaps the prey of some predator.
SNAKESKINS IN BIRDS' NESTS [Ref]
There are occasionally discovered behavior patterns of birds that are so unusual as to make one stop and wonder. They are unusual for birds generally, but in a species here and there they are the regular thing. Such is the placing of a shed snakeskin in their nests by some birds.
A bird like the English sparrow, or the road runner, which uses a variety of material coarse or fine, would be expected to use shed snakeskins occasionally, as it came across them. But there are a number of species that seem to use snakeskins regularly in their nests. It would seem that the birds deliberately sought out the skins for this purpose, as though they were as much a part of the nest as the mud in the bottom of a robin's nest or the fresh green grass heads ornamenting the entrance to some weaverbirds' nests.
SOME HABITS BAFFLING I have long since given up thinking that every aspect of a bird's life must serve a useful purpose. Indeed I have already pointed out some definite maladaptations. But usually every type of behavior has a logical origin. By considering its occurrence in various species and against the background of the bird's everyday life some correlations usually can be found.
The list of birds habitually using snakeskins in their nests is short, as follows:
1. Great-crested flycatcher—belonging to the New World flycatchers, breeding in Eastern North America and nesting in holes.
2. Arizona crested flycatcher—a relative of the great-crested variety, with similar habits.
3. Blue grosbeak—an American member of the sparrow family, making an open nest in bushes.
4. Black-crested titmouse—a member of the chickadee family, living in Western North America and nesting in holes.
5. Bank mynah—a starling, living in southern Asia and nesting in holes in banks.
6. Rifle bird—an Australian bird of paradise, making a cup-shaped nest in trees.
7. Madagascar bulbul—making a cup-shaped nest in trees.
LIKE A DECORATION Twenty or more other species of birds have been recorded as using snakeskins more or less commonly, or occasionally perhaps on the basis of availability or of chance. But with the above they're an essential part of the nest. In some of the species the snakeskins are arranged as a rim around the edge of the nest almost as a decoration; sometimes the snakeskins may make up most of the nest.
Now as to possible correlations. The species are not closely related. Except for the two flycatchers the other five represent five different families. The distribution over the world is wide, too: America, Asia, Madagascar, Australia. Various explanations for the behavior have been advanced. It has been suggested that it's correlated with hole nesting, but three of the seven do not nest in holes. The most common theory is that it's to frighten away possible predators by making them think there is a snake in the nest. However, this is not very likely, and, too, one wonders why the birds that use the snakeskins are not frightened themselves. Indeed, one writer, surely not seriously, has suggested that the fright in early life of crested flycatchers at finding a snakeskin in the nest accounts for the upstanding crest in this species!
"BURGLAR ALARM" THEORY Another suggestion is that the snakeskin, by the rustling noise it makes when touched, acts as an alarm bell or a burglar alarm to warn the rightful occupants of the nest when an intruder approaches. This also seems a rather weak explanation.
We are left, then, with the fact that this curious habit has been developed in a few birds, not closely related, that live in various parts of the world and that have very different habits. It is usual with them. A number of others occasionally have this habit.
My first clue as to the proper background against which to solve this habit came when, unpacking a bird collection made in Borneo by curator of anatomy D. Dwight Davis, I took out a bulbul's nest. In its outer edge were flat, weathered leaves that resembled snakeskins. Later, when we received a bird collection from Dr. D. S. Rabor of the Philippines there was a nest of another species of bulbul and this too had flat, dead, weathered leaves in it that looked like snakeskin. When I was in Madagascar, in 1929-31, I had found three nests of the Madagascar bulbul with a snakeskin used in each. Here was a clue. I decided to investigate the nests of the other species of bulbuls of southern Asia and Africa where the family is represented by many species. By considering the snakeskin-using species against the background of the nesting of the other species some correlation might appear.
BOOKWORK This became a library problem at once. I had to look up the earlier reviews of the problem in the ornithological journals, The Auk and the Ornithologische Monatsberichte, then in Strong's Bibliography of Birds, to make sure that no important papers were missing from my own subject file. Stuart Baker's Fauna of British India, Birds had a large part of one volume devoted to bulbuls, and gave excellent summaries of the nidification of each species occurring there. Bannerman's Birds of Tropical West Africa covered the western part of that continent, and Jackson's and Sclater's Birds of Kenya Colony did the same for the eastern part. For collateral material I looked in Mathews' Birds of Australia, Volume 12, Forbush's Birds of Massachusetts, and Mrs. F. M. Bailey's Birds of New Mexico, and a dozen minor publications.
But it was worth it.
Perhaps my earlier thinking was dominated by the thought that the shed snakeskins had been parts of animals toward which many birds show an antipathy. But it's extremely probable a bird does not recognize the snakeskin as such. Rather to it the shed snakeskin is a strip of thin, flexible material. Obviously it would be used, by chance, by many bird species, such as the house wren, which, in addition to using such natural materials as twigs, grass, and hair, has been recorded as using lead pencils, paper, nails, safety pins, and snakeskins in its nest.
As to the regular users of snakeskin, the snakeskin-using Madagascar bulbul did fit into a pattern. Bulbuls in general make characteristic simple cup nests. Some species use almost any available material. But quite a few species had specific choices of materials: one species' nest had tendrils of vines in its base; another a lining of grass heads of a certain color; another pine needles; another red dead leaves; and the Madagascar bulbul snakeskins.
A SOLUTION There seems to be a tendency for many species to make distinctive nests. They often accomplish this by a choice of material used by few or no other species. What more natural than that one species, being in a country where snakes are common, should hit on shed snakeskins!
To show that the choice of snakeskin as nesting material is an expression of a tendency for each species of bird to make a different kind of nest may not be much of an answer. But it is to an extent. No longer do we say, "Why are certain birds' nests characterized by snakeskins?" Rather we have the broader, more general question, "Why does each kind of bird tend to build a nest different from that of every other kind?" Thus, little by little, we clear away small, vexing questions and resolve them into larger, more general questions. For answers to these we sometimes plan extended work involving field studies, studies of specimens, and books. And sometimes, as we examine a specimen, read a paper, or unpack a shipment, an answer, or at least a clue, springs to our mind.
CO-OPERATION BY BIRDS [Ref]
The importance of co-operation, contrasted with competition, has assumed increased importance in discussions of evolution, as it has in discussions of human social progress. Co-operation in nature is of various kinds; from the manner in which a forest shelters the squirrel to the manner in which two or more individuals of one species work together for a common object. The working together of two birds to rear a family is so well known an affair that one forgets that it is an example of co-operation, not only in building the nest and brooding and feeding the young, but also in defending the nest and the young.
Sometimes more than one species will join in ousting an enemy. For example, when a cat caught a young robin, recently out of the nest, the parents, in their frantic effort to make the cat release the bird, attracted the attention of another robin and a pair of cardinals nesting nearby in a honeysuckle. All five birds dived at the cat, screaming and pecking it so vigorously that it released the young robin and fled.
EAGLES JOIN EFFORTS More spectacular are some of the co-operative activities of birds in food getting. Bald eagles sometimes feed on ducks. Frequently two eagles may combine their efforts. The two birds may work together to force a black duck from the air onto the water, and when they are trying to catch a diving duck, they much more quickly exhaust their prey by swooping at it in turn. Bald eagles sometimes take water birds too large for them to carry, and then they must flap along dragging their prey on the surface of the water to the nearest shore. On one occasion an eagle dragging a large cormorant ashore was joined by two other birds, and all three took turns in dragging it. When they got it ashore, all three shared it.
Several fish-eating birds co-operate in capturing their prey. "The merganser is primarily a fishing duck ... very skillful and a voracious feeder. It pursues underwater and catches successfully the swiftest fish. Often a party of sheldrakes may be seen fishing together, driving the panic-stricken fish into the shallows or into some small pool where they may be more easily caught," according to A. C. Bent.
When a school of fish approached a flock of white pelicans, the birds suddenly assumed a circular position, surrounding the school. All the pelicans moved slowly but cautiously toward the center of the circle, their heads near the surface of the water or partly submerged and their necks slightly extended. The birds moved in perfect unison, making the circle progressively smaller, ready to engulf their helpless victims at the first opportunity. When all the pelicans were close to the fish, the birds made rapid jabs at the fish and apparently consumed a large number of them. It appeared that every bird got from one to several fish.
13,000 BAND TOGETHER Avocets and, to a lesser extent, the black-necked stilts also band together for co-operative drives on small fry and aquatic insects. Such drives are made in water of wading depth. Instead of forming circles the birds present compact spearhead and wedge formations and sweep the bottom muck with the characteristic back-and-forth side movements of their long bills. As many as 13,000 avocets have been observed taking part in such co-operative feeding projects.
Another striking example is furnished by black vultures observed by E. A. McIlhenny. A three-quarters-grown skunk was wandering across a field. A vulture alighted near the skunk which immediately stopped and raised its tail. Other nearby vultures joined the one nearby the skunk, and when six or eight of them had gathered one suddenly attacked it. The skunk immediately discharged its defensive scent, but without effect, for the vultures attacked in a mass and other vultures circling above joined in until there were probably twenty-five or more around the skunk. With much flapping and croaking, the vultures pulled it about until it was dead, and then devoured it.
On another occasion a black vulture came from high in the air to alight near two full-grown opossums following a narrow cattle trail. The first vulture was almost at once joined by many others until there were probably between seventy-five and one hundred black vultures following the opossums. Suddenly three or four of the vultures attacked and the others joined in. Quickly both opossums were covered with a swarm of hissing, flapping birds, and within fifteen minutes there was nothing left of them but the larger bones and the hides, and these were stripped of every vestige of flesh.
WATCHDOGS AT THE NEST [Ref]
A savage watchdog outside his master's house helps to protect it. If an intruder comes, the watchdog, if it's the right kind, simply bites him without preliminaries. There's a parallel to this in the bird world. Some birds often have their nests close to wasps' or bees' nests, or in trees inhabited by biting ants. The birds and the ants, wasps, or bees get along without disturbing each other. But when intruders come along the insects swarm out, biting or stinging and driving the intruder away. The insects are protecting their own homes, but one of the results, the protecting of the birds' homes, is just as satisfactory to the birds as if they did it on purpose. This building of birds' nests close to wasps' nests is a common practice with certain sunbirds and weaverbirds, especially in Africa. It occurs too often to be chance. The question naturally arises as to how much the birds understand of it all—do they actually seek out the association? That's difficult to say, but the facts of the association are still there.
Though some of these associations are evidently fairly common and chosen deliberately by the birds—and one can easily visualize how the protection works—field observations as to the natural enemies against which they are effective, and how effective they are, are largely lacking. Usually the records are something like those of Van Rossem for the Giraud's flycatcher in El Salvador, in which he points out that this bird usually nests in certain mimosa trees armed with numerous heavy, curved thorns. These thorns are hollowed out and inhabited by swarms of small but extremely hostile antlike insects, so that the nest is well protected. However, the effectiveness of ant and bee protection against human predation can be seen in the following.
Take the case of Mr. M. E. W. North, who arranged a rope to climb to a fish eagle's nest in East Africa. He had gotten about fifty feet up and was considering going out on the big limb on which the nest was, when he noticed a wild bee on his sleeve. Realizing that he was disturbing a wild-bee hive, and knowing that the sting of these vicious bees can be dangerous, fatalities having been reported, he came down his rope at express speed, crashing through projecting branches and brambles. Reaching the ground, he freed himself from the rope and fled to a safe distance, considering himself lucky to have received only three stings.
On another occasion, again in East Africa, Mrs. R. E. Moreau attempted to reach a hawk's nest to measure the eggs, but when she was up in the tree, savage, biting red ants drove her out.
BIRD GUIDES TO HONEY [Ref]
In Africa there are birds which lead men to honey. They are called honey-guides and their family name, Indicatoridae, has the same idea incorporated into it. Though there are several species of these small, dull-colored birds, which are related on the one hand to woodpeckers and on the other to barbets, it is only one species, the common or black-throated honey-guide that is well known as a guide to honey.
The traveler in the country may find one of these birds chattering and flying ahead of him. The natives, who know this bird well and favorably will tell the traveler to follow; it will lead to a bee tree. The native, as he follows this guide, gives occasional whistles, as if to encourage the bird. The bird continues, flying from perch to perch, ahead, and chattering noisily. Sometimes it may return to see if the men are following; sometimes it remains chattering on its perch until the followers catch up. Finally the bird will go no farther. It flies about aimlessly and allows one to approach closely. This is the spot. In a hole in the tree trunk, or in the ground nearby the bees' nest is to be found.
When the beehive is opened, and the honey taken, the honey-guide will eat the comb that is left, and apparently it is for this that the complicated behavior of leading of man to the beehive is developed.
Wax of the honeycomb is a usual food of this species, judging by stomach examinations, and one wonders how they get it when man is not about to open the bee trees for them. The birds have no special adaptation for getting into the hives; indeed their only apparent adaptation for this habit is a thick skin, perhaps a protection against bee stings. Perhaps, as has been suggested, other animals, squirrels, monkeys, or honey badgers may unwittingly aid them by opening up bee trees for their own purposes and allow the honey-guides to snatch food for themselves.
An amusing side of the picture is that sometimes the honey-guides may lead the honey hunter to a beehive owned by a native.
There are also records of the honey-guide leading men to big game: leopard or lions. That this occurs is amply documented, but one wonders whether or not this was accidental; the honey-guide leading the way to honey perhaps by accident leads the way past the resting place of one of these big cats so that the man stumbles over the big game and perhaps gets the impression he was led to the animal.
OXPECKERS [Ref]
The lives of oxpeckers are so linked to those of large, hoofed game or domestic cattle that in West Africa where game is scarce the birds depend on cattle, and their range is restricted accordingly. There the cattle are confined to the higher and more northern areas, free of tsetse flies, from Senegal to Northern Cameroon. Thus tsetse flies help to determine the limits of the oxpeckers' range.
Except for their nesting, which is in holes in trees, and their sleeping, most of their time is spent on the bodies of the larger herbivores. There they run about over the hides and legs of the beasts, like woodpeckers on a tree. They stay remarkably close to the animals, and even ride on them as they travel. The oxpeckers' food is largely ticks, which it gets from the hide of the animal by working over it with the side of its bill, shearing off the ticks with a scissorlike action of its mandibles. But when an animal has sores or cuts or scratches the oxpecker may peck into them, and eat flesh and blood of its host.
Correlated with this unusual and close relationship, a modification in the oxpeckers has taken place. There are only two species, both African, and they are dull-colored, modified starlings. The legs are stout, with curved, very sharp claws for clinging to the hides of animals, and the bill, very sharp at the tip, with the cutting edge of the mandible very sharp to aid in scissoring off ticks.
All the larger herbivores are attended by oxpeckers except the elephant and the hippo, but the favorite seems to be the rhino, and for this he's sometimes called the rhino bird as well as tickbird and oxpecker. The rhino gives the bird its food, and in return the bird provides a service of a value difficult to evaluate. It acts as a sentinel and may warn the rhino of the approach of hunters, for which habit it is execrated by sportsmen.
It would seem that such relationships could have developed only where the supply of big game was large. With the introduction of cattle and other domestic animals it was natural the oxpecker should turn its attention to them. Here the question arose as to the attentions of the oxpeckers being harmful or otherwise to the herds. Mr. R. E. Moreau, formerly of the East African Research Station at Amani, has investigated the problem. He finds that white men who own herds tend to consider the oxpecker a nuisance; Africans tend to consider it beneficial and some African cattle owners object to having the birds killed; the beasts themselves tolerate the birds.
There is the possibility on the one hand of oxpeckers spreading certain cattle diseases that are mechanically transmitted, and on the other hand they may help reduce disease by eating ticks, the vectors of certain diseases. Of course dipping the cattle takes care of ticks on them, and here we see another indirect effect of civilization on bird life. When cattle have been dipped the oxpeckers disappear from the herd. Perhaps it is because there is no longer food for them there; perhaps they get enough of the poison dip left on the beasts' hair to be lethal.
WINGS IN FEEDING [Ref]
The obvious adaptation of a bird's wings is for locomotion; to fly in the air. It is true that some few birds are flightless, and some like the penguins use their wings for underwater swimming, but this does not spoil the generalization.
Secondary uses, some with special adaptations, occur: the owl at bay spreads its wings wide, with the effect of increasing its apparent size and being more terrifying to a predator. The young bird, begging to be fed, flutters its wings in a characteristic way, and the female, in some of her mating behavior, may also flutter her wings like those of a young bird.
In courtship the wings may play an important part in display. In the Australian rifle bird they are held out, fully spread on each side of the bird like a velvet curtain against which the vivid iridescence of the throat patch stands out more vividly. The argus pheasant has the inner secondaries greatly elongated and ornamented in a fashion recalling the decoration of a peacock's tail and these he spreads to show in his courtship, while the ruffed grouse uses his wings to make instrumental music, his drumming.
Wings in geese and swans may be used in fighting, and tame birds may severely buffet humans who take too close an interest in their young. In the related screamers of South America the bend of the wing is equipped with long, very sharp spurs, which undoubtedly make formidable weapons in fighting.
In addition wings are used in at least three different ways in feeding. The red-tailed hawk may spread its wings as it sits on its prey, perhaps a behavior adapted to help the bird maintain its balance when dealing with struggling prey, perhaps to help smother the struggles of its prey.
The secretary bird of Africa is said to feed on snakes, poisonous and non-poisonous ones, and is said to use its huge wings as shields for its body in attacking them.
But the strangest use of wings in feeding is that practiced by a blackish African heron. In feeding in shallow water it takes a few rapid steps, apparently to bring it within reach of fish it has sighted, then spreads its wings, bringing them forward until they meet, and with the tips of the quills in the water. The head is in the canopy formed by the wings, and apparently it is here under this canopy that the fish on which it feeds are caught. The suggestion as to the correlation that presents itself is that the dark canopy thrown over the fish confuses them and makes them easier to catch.