Part 8

Then in Britain came a whole host of records, after an observation in Holland in 1946 of curlew sandpipers washing food. The birds were probing the dry mud at the edge of a little creek. When one of the birds got a small sand worm, it at once ran with quick steps to the creek and stepped into the shallow water, where it dipped the worm a few times into the water before swallowing it. Then it trotted away for more. The editor of _British Birds_, the journal in which this was published, suggested that this might be a more common habit than the scanty published records would indicate, and invited observations.

A spate of records resulted in the succeeding numbers of the journal: a whimbrel washing crabs; a snipe, earthworms; godwits washing their food; with curlews it was reported to be normal; dunlins, greenshanks, redshanks, ringed plover, and oyster catchers were all reported doing this until it appears that with the group of birds we call shore birds--sandpipers, snipes, plovers, and their relatives--it may indeed be normal. The details of the observations strongly suggest that the reason for the washing, in many cases at least, is the same one that underlies our washing spinach; to get the sand and mud out of it.

HOW ANIMAL VOICES SOUND TO FOREIGN EARS

When in El Salvador in 1951, I found that the common barnyard animals had much the same voices as the ones with which I was familiar in the United States. But when I saw their utterances written down it was another matter. The voices written in Spanish sometimes looked as different as the names of the animals written in Spanish. Take the donkey, for example (or _burro_, as they call it in Spanish). In English we call its "song" "Heehaw!" In Spanish they wrote it for me, "Aja! Aja! Ija! Ija!" There were a number of German scientists at the Instituto Tropical de Investigaciones Científicas, where I was working, and for comparison I asked them to write for me what the same animals said in German. The burro (_Esel_, they call it in German) says, "_Ihå! Ihå!_" in German. Despite the difference in the appearance of these words, when they were pronounced by the various nationalities they sounded very similar. Compared with the original assinine pronunciation, the Spanish version was awarded the prize for being the best rendition of the beast's voice.

The cat's "_Miau, miau, miau_" in Spanish, "_Miau, miau_" in German, and "Meow" in English were all very similar in appearance as well as sound. The duck's voice came out differently. In Spanish it was "_Cuá, cuá, cuá_," in German "_Wack, wack_," and in English the initial "Cu" or "Q" sound of the Spanish, and the final "k" sound of the German are united into "quack." The hoot owl came out much the same in pronunciation, though it looked different in the Spanish "_Ju_," in German "_Hu_," and in English "Who."

The cow's, the pig's, and the frog's voices were also rather similar in the three languages: the cow's in Spanish being "_Meu, meu, muuu_," in German "_Mŭh, mŭh_," and in English "Moo"; the pig's "_Grup-grup, wink_," "_Óŭik, Óŭik_," and "Grunt, oink"; and the frog's "_Cruac, croac, croac_" "_Quak, quak_," and "Croak." The barnyard rooster has a difficult voice to transcribe in letters. In Spanish it was "_Quiquiriguiiii_," in German "_Kickeriki_," and in English "Cock-a-doodle-do." After listening to the various renditions by the various nations I could see how each rendition came into being, but as for deciding which was closest to the original I hesitated to choose.

When it came to the dog, the discrepancy was surprising: in Spanish it was "_Guán, guán, guán_," in German "_Waŭ, waŭ_," and in English "Bowwow." The German and the English are close enough. But though I went outside and listened to the dogs in Salvador, never did they seem to say, "_Guán, guán, guán_," though I must admit that neither did they seem to say, "Bowwow."

SIGHT IDENTIFICATION

Sometimes when I'm trying to decide whether the birds of the Cameroon Mountains of West Africa are the result of one invasion and variation _in situ_, or of two invasions, or whether the Himalayan red-billed choughs of Ladak are different from those of Nepal, or how the molt of the cassowary resembles that of penguins, I am called to the telephone to identify a bird someone has seen.

The chances are it's a starling. I've not kept a record, but I fancy half the questions are on identification of starlings. In the distance starlings are black, and people know them. But close up, where details can be seen, they puzzle people with their variety. The young may be dull brownish; the adults may be speckled in the winter; in the spring the speckled tips of the feathers wear off and they're all black. But the black is iridescent, and in sunshine glitters purple or greenish. And the bill color changes too: it becomes yellow in the spring.

Sometimes it's surprising how you can spot a bird from a brief description. Take this one: a bird that sits with its stomach on the ground, and has a big mouth, and long whiskers; a whippoorwill obviously. Or take this one: a bill like a chicken and with flat feet at the back; obviously a pied-billed grebe.

There was one that absolutely stumped me for a day. The lady said it had a bill like an eagle, and a tail that stuck up. For the rest she was vague. Often habits, actions, or habitat are a help to me in placing a bird, but I could get nothing to help--not even where she had seen it. I admitted I couldn't help her. The next day someone brought in a picture puzzle out of a newspaper, and there, right in the center, was my bird. It was a dodo! We don't mind helping people learn things, indeed we consider it part of our job, but to help them work puzzles is too much!

MY LESSON Sight identifications of most students probably contain errors. On common species it's not important, as quantitatively they cancel out. But when a bird tripper, anxious to make a new record, wants me to help him decide he saw an exotic tern, I'm very careful--I've had experience. Rarities have to be checked on all points, not identified by elimination or on a few key characters. One of the best lessons of caution I had in New Guinea. It was in the mountains. Each morning I hunted in a forest where I'd found a new genus of bowerbird. Anything might occur, I thought. Then I saw flying through the treetops what could only be a magpie. A long-tailed, black and white bird, its pattern was unmistakable. There was nothing like it known from New Guinea. It would be an extension of range from Asia. Or it was a new and unknown species. Anyway I needed it as a specimen. But it was shy and eluded me. Morning after morning I haunted the forest. Finally I got the bird. And it turned out to be a partly albinistic specimen of a common, black, long-tailed bird of paradise. The abnormal white areas in its plumage had fooled me completely. But it helped teach me caution as to sight identifications.

One of my Gary friends, Mr. Raymond Grow, who is a keen bird student, has the proper approach, as his identification of a winter duck showed. There were a number of unusual winter birds that season (1951-52): brown-headed chickadees, pine and evening grosbeaks, and red-breasted nuthatches, all from the North, were present. It was the sort of winter one expects other rarities from the North.

DUCK CAUSES CONFUSION Mr. Grow had seen at the edge of Lake Michigan a duck he didn't know; it was boldly patterned in black and white, a big duck. An immature male eider seemed the only possibility. He came into the museum and we went over specimens, noting the difference in the shape of the head between the king and the common eider. He studied the descriptions and the plates. Nothing quite fitted. Unsatisfied, he went back to Michigan City, found the duck again, and suddenly realized it was a muscovy duck, partly albinistic, and escaped from someone's barnyard.

It's not the first time a muscovy has caused confusion. Only a year or so ago we had a duck sent us from the Philippines that our correspondent wrote was shot swimming in a river with a Philippine mallard and surely represented a new species. But it turned out to be a muscovy whose original home is tropical American but has become domesticated and transported by man to far parts of the globe. Occasionally birds escape and take to the wild, even as this Philippine bird had done.

GREEN HUNTING JAYS TURN BLUE

Sometimes in "working out" a bird collection things get dull. In identifying the specimens, and writing down why they are this species, or that species, or subspecies, it seems routine; as though it were simply routine putting things in the categories ready for them.

Such was my feeling one day as I worked over Himalayan jays and magpies from Nepal. I'd done the yellow-billed blue magpie, and the red-billed blue magpie, which both fell into their places smoothly. Then I got out the literature, the pertinent keys, and descriptions for the next species, the green hunting jay. It's a beautiful, pale, apple-green bird, with a green crest, and set off by dark red wings. It checked with the descriptions, and I wrote _Kitta chinensis_, its scientific name, on the label. Then, to check the species' identification and to determine the subspecies, I turned to the collection, to the birds from India, Siam, and north Indochina, which should all be the same.

I pulled out the drawer--and blinked at the jays, rows of them; all pale blue with brown wings. I looked at the name on the case, on the tray, and the name on each specimen. They all said the same, _Kitta chinensis chinensis_, and it was the bird described as green, like my new specimen. It was uncanny. The new green specimens and the old blue ones were identical in size, in structure of bill, crest, feet, tail; they must be the same. And they were. The book, I found, described how the colors changed with age, and in John Gould's magnificently illustrated folio, _Birds of Asia_, published in 1861, he had the green hunting jay depicted both as a green bird with red wings and, in the background, a "blue" green hunting jay like our museum specimens. When alive, and when freshly killed, the birds are green. But with the passing of time the green changes to pale blue, and the red wings to brown wings. Probably my new specimen, now a year old, is less green than it was when fresh. And when twenty years old, like our museum skins, it will be blue too.

The riddle was solved, and it fits into a well-known phenomenon, "museum age" or post-mortem change. "Foxing," we call it for short. We see it in the male American merganser, where the lovely rich salmon color of the fresh bird becomes plain white. The emerald cuckoo of Africa has vivid rich yellow under parts when fresh, and this too becomes dingy white. Gray Canada jays become more brownish. Birds that are olive or other shades of green tend to become more olive; brown birds tend to become more russet or foxy (hence the term "foxing"). We keep all our specimens in dustproof, lightproof metal cases. The change is not caused by fading. Apparently it's a change in the pigment, perhaps from oxidation.

Taxonomists, the men who classify and name birds, have been fooled by it. Old skins used to represent the birds of an area may give a quite different idea of what they are like than do fresh skins, and when skins of different age are compared, the conclusions may be wrong.

Foxing is one of the pitfalls for the unwary taxonomist, and something he has to guard against.

HOW BIRDS USE COWS AS HUNTING DOGS

The sportsman out for quail or woodcock uses dogs to drive out the birds for him. Starlings and cowbirds about Chicago use the same principle in hunting grasshoppers. Instead of dogs they use cows, though of course the cows are intent on something else and presumably unconscious of the fact that they're helping the birds.

As the cow grazes slowly across a meadow, it scares up grasshoppers close in front of it. The cowbirds and starlings take advantage of this. Instead of covering the meadow on foot, constantly alert for a sitting grasshopper, or to chase one they flush, the birds keep with a grazing cow. They take up a position by the head, or a foot, and catch the insects the cow disturbs. The cow is so much larger than the bird that it is likely to flush more insects. The grasshoppers on the wing are much easier to see than when at rest in the concealing grass, and some fly directly toward the bird. Too, the grasshoppers fleeing a cow are less likely to be alert to other dangers.

CONFIRMED BY OBSERVATION The advantages of this to the bird are obvious. But we've just assumed they were, and we had no data on the relative efficiency of the two methods of hunting. A few years ago, however, while in El Salvador, I was able to get quantitative data proving that using a cow as a beater was advantageous, as we suspected, and showing how much more effective it was, something we did not know.

The bird concerned was not the starling, which does not occur there, or a cowbird, which occurs but consorts little with cows, but was the grove-billed ani, a black cuckoo about twelve inches long of the tropics of Central and South America. Like our starling and our cowbird, it kept with cows, catching the grasshoppers and other insects that flew up. Both anis and cows were common in the grassy fields about our headquarters in San Salvador. We decided, my son Stanley and I, to watch anis with cows for a few hours, and then without cows for a few hours; thus getting the average rate for each type of feeding. We quickly found it wasn't as easy as that. Something always happened; even on the levelest and most open fields the birds were constantly disappearing behind a tuft of grass, or in a hollow, or, if nothing else, behind the cow's head or feet. Then, too, the ani we elected to watch wouldn't pay attention to the job in hand. It would wander off, or go to sleep. And sometimes, when we were about to discontinue watching a somnolent bird, it would snap up an insect. Perhaps it had been watching all the time. Finally we found we had to record observations of many short periods, of from three to fourteen minutes each, and add them together.

By dint of much patient watching we got our data. In the dry season when insects were scarce and the grass short, it took an ani, hunting alone, two minutes on the average to find an insect. In the same length of time hunting with a cow the catch averaged three insects. Thus hunting with a cow as a beater was three times as effective as hunting alone.

The effect of the change of the season in abundance of food for the ani was very striking. In the wet season the grass began to grow fast, and insects became common. Then the anis had an easy time. Without a cow an ani averaged between three and four insects a minute, more than six times as much as in the dry times. There was less incentive to use a cow as a beater, with food so abundant, but when the ani did so, its rate of finding insects was still higher: between four and five insects per minute. In a table it looks like this:

_Average Number of Insects Per Minute Found by Ani Feeding_

WITHOUT COW WITH COW

Dry Season .5 1.5 Wet Season 3.4 4.7

But the three-times-greater-results in a given time in the dry season do not tell the whole story as to the effectiveness of using a beater. When an ani was hunting by itself it walked about, covering a surprisingly large amount of ground. When using a cow as a beater, not only did it catch more insects in a given length of time, but it also walked about much less, saving a great deal of energy.

This is not true co-operation between cow and bird, for they're not working together toward a common end. It's not exploitation of the cow by the birds, for the cows lose nothing. It is closer to a form of harmless parasitism, for the ani profits from the activities of the cow without either harming or helping the cow. It also illustrates how sharp birds are--ready to take advantage of any factor in their environment that will help them get their food.

EARLY BIRD LISTING

I wonder how many of the people who go out making lists of spring birds know that bird listing goes back to ancient times. It's a modern sport, but earlier bird watching was serious, and a competitive listing of birds played a part in as important an event as the selection of the site of the city of Rome.

The story, as Plutarch tells it, is that Romulus wanted the city on what became known as Roma Quadrata; Remus wanted it on the Aventine Mount. As was the custom in those days, they concluded at last to decide by a divination from a flight of birds. The twins placed themselves apart at some distance and watched. Remus, they say, saw six vultures, a truly notable flight; Romulus saw twelve and from this rare and unusual occurrence Romulus' choice of the site for the city was accepted.

VULTURES HIGHLY REGARDED Partly from this the vulture became chiefly regarded by the Romans in their divinations from birds. But even before this the vulture was highly regarded. Hercules, it was said, was always very joyful when a vulture appeared to him upon any occasion. He considered it the least harmful of creatures; not pernicious to corn, fruit tree, or cattle, it never killed or hurt any living thing. It was also thought not to eat other birds, a weighty point in its favor, as Plutarch quotes from Aeschylus, "What bird is clean that preys on fellow bird?" And apparently its deciding claim to esteem was its rarity and infrequency, which gave rise to the opinion in some that it came from another world, an opinion foisted by the soothsayers of the day.

Earlier yet, birds played a part in Rome's history. Plutarch warns that some give you mere fables of the origin of Rome, but it is widely current that Remus and Romulus, fathered by Mars, the God of War, were exposed in a remote place to perish. This would have taken place, but for a she-wolf that nursed them, and birds of various sorts that brought little morsels of food which they put into their mouths. Some, however, hold the belief that not birds of various sorts but a woodpecker was the bird that constantly fed and watched the twins, and even in Plutarch's time the Romans still worshiped and honored the woodpecker for this service to the founder of the city.

BATTLE OF THE SEXES AND ITS EVOLUTIONARY SIGNIFICANCE

I used to think that the battle of the sexes so ably portrayed by James Thurber was artificial, a man- and/or woman-made thing. But recently I've come to see it as old--probably as old as sex itself in the animal world.

Under the severe tide, "Secondary Sexual Characters and Ecological Competition," in a paper from the Bird Division of the Chicago Museum, I've outlined the possibility of competition for food, between the sexes, being a factor in evolution, responsible in part for characteristics of structure and traits that distinguish them.

In circles that discuss evolution the idea is current that food competition is important between species. It may even be stated as a rule: two species with the same food habits cannot live in the same place. Competition drives one out, unless they have different food habits. These differences seem especially evident when you look at closely related species, and they are accomplished in a variety of ways. A habitat difference is very common. The long-eared owl hunts in the woods--its cousin, the short-eared owl, hunts the meadows; the song sparrow favors the drier shrubbery while its cousin, the swamp sparrow, lives in wetter shrubbery.

THE SIZE FACTOR Sometimes the difference is accomplished by size; take the downy and hairy woodpeckers of our wood lots, very similar except that one is larger and is adapted for larger prey, the other smaller and adapted for smaller food items. Sometimes they feed differently, as the Baltimore oriole, which picks flowers and pecks through their sides, while the orchard oriole probes into flowers as they hang on the branches. Thus more individuals of several species live in an area.

When a pair of birds "sets up housekeeping" and starts "raising a family" they can no longer drift about, looking for easy living and places where food is plentiful. Their wanderings are restricted by having a fixed point, the nest, as their center of interest. Two individuals must draw on the food supply from an area about the nest. Competition would be extreme, and, if there were a scarcity, perhaps critical.

We know how different the sexes may be; how different the rooster is from the hen in our domestic fowl, or the drake and the duck in the mallard, or the red male and the green female of the scarlet tanager. These sexual differences have mostly correlated with display and mating. But logically there should be differences in feeding behavior and adaptations between the sexes.

The basic idea is contained in the old nursery rhyme:

Jack Sprat could eat no fat, His wife could eat no lean; And so between them both, They licked the platter clean.

The two birds of a mated pair, limited to a single area, could be expected to have different food preferences or adaptations for getting it. And we find that there are cases of this. The most striking is that of the huia from New Zealand, of which I've written in a Chicago Museum bulletin. Both sexes have similar food preferences, especially wood-inhabiting insects, but they get them in different ways. The male has a short, straight, stout bill for digging out the wood-boring grubs, woodpecker fashion; the female has a much longer, slender, and curved bill for probing into holes for them, creeper fashion. The female may get grubs in wood too hard for the male to chisel. They supplement each other.

DIET VARIATION BY SEX It is possible that further study may show more sexual differences to have a feeding advantage; the larger size of female hawks fitting them to take larger prey; the smaller size of certain female songbirds fitting them for smaller prey, the smaller bills of female hornbills, the straight bill of the male western grebe, and the upturned bill of the female. Perhaps all are of advantage to the species in giving each sex slightly different advantages in getting food.

Selection could have its effect in the populations with most sexual difference in feeding habits being most successful in raising and leaving progeny. Thus, slowly, differences between the sexes would accumulate. However, it must be kept in mind that this sort of evolution would be limited. The drifting apart of the sexes would be checked by the necessity for their coming together periodically for at least a short period, at nesting time.

WATER IN THE DESERT

Water is a precious thing in the desert. Without it no life is possible. When rains come plants spring into vigorous growth. During the long stretches without rain they rest, some as seed, while some plants store water in root systems, or in large trunks. Animals have developed a number of ways of surviving long dry spells in arid country.

Among mammals the kangaroo rat of our Southwestern desert seems able to get along without water. This is caused by an arrangement within the body whereby the necessary water is manufactured within the animal from other foodstuffs: metabolic water.

The accessibility of drinking water in a desert may be the determining factor in whether or not some birds can survive there. The nests of Gambel's quail must be close enough to drinking water for the newly hatched young to walk there, else they perish of thirst. It has been said that newly hatched chicks of the related valley quail of California cannot travel more than a few hundred yards from their hatching places without water. Broods hatched farther away are doomed to die.