Popular Science Monthly/Volume 44/January 1894/Night Hawks and Whip-Poor-Wills

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NIGHT HAWKS AND WHIP-POOR-WILLS.
By Dr. R. W. SHUFELDT.

THERE is hardly a season goes by that I am not asked, by some one more or less interested in our native birds, "What is the difference between a night hawk and a whip-poor-will?" Generally the belief is that these two very interesting forms are one and the same species; but this is by no means the case, and a full reply to the question leads us to the consideration of one of the most attractive groups in the entire range of our American avifauna. A number of years ago the writer made a very careful study of the representatives of this family as they occur in our country, and some of the more important facts as brought out by that research will be set forth in the present article. Those most familiar with the habits and anatomical structure of night hawks and whip-poor-wills and their allies place them in a suborder Caprimulgi, which primarily presents us with a family Caprimulgidæ, which family in the United States contains at least the four very distinctive genera Antrostomus, Phalænoptilus, Nyctidromus, and Chordeiles. To the first-named genus belong the true whip-poor-will (A. vociferus), together with Stephen's whip-poor-will, and the chuck-will's-widow of the Southern States, with others. Phalænoptilus Nutalli, the interesting little poor-will of the Western States, is found in the second genus, while Nyctidromus albicollis is representative of the third. Finally, in Chordeiles we have the night hawks, as the common form, C. virginianus, as well as the Western night hawk, the Cuban night hawk, and the Texan night hawk (C. texensis).

To start with these it will be seen that our night hawk and our whip-poor-will belong to two very different genera of the Caprimulgidæ. Not only is this the case, but these two birds are in habits and in structure more widely separated from each other than is the whip-poor-will from any other genus of the family. Indeed, night hawks are quite aberrant types, while, as a matter of fact, none of our United States caprimulgine birds give us any hint of the extraordinary foreign representatives of this suborder, some of which will be referred to further on.

Upon comparing a night hawk with a whip-poor-will we find that, apart from the very well defined difference these birds exhibit in their internal structure and in the general tone and markings of their plumage, there are a few external striking features that ought to enable any person to distinguish one from the other at the most casual glance.

I refer especially to the long, conspicuous bristles projecting from about the mouth of the whip-poor-will, a character almost entirely absent in the night hawk. Further, the tail of the former is very much rounded, with its four middle feathers like those of the back, the three outer ones, on either side, having their terminal halves white. In the night hawk the last-mentioned portions are black, and the form of the tail is very different. Our night hawk also has a distinctive white patch on the outer aspect of each wing, which is not present in the whip-poor-will. Again, the habits of these two birds are by no means similar. The whip-poor-will, with rare exceptions and under certain circumstances, is active and feeding from dark until daylight, and sleeps on the

PSM V44 D321 The night hawk c virginianus.jpg
Fig. 1.—The Night Hawk (C. virginianus),♂. Drawn by the author and much reduced.

ground in the forest all day, the very reverse of this being the case with the night hawk. In some localities the latter is known by the name of the "bull bat," the first word undoubtedly having reference to the booming noise it emits during its plunging freaks through the air, in which it indulges while out abroad for food. Audubon and Wilson disagreed on the score as to how this noise was produced by the bird, the former claiming that it was performed by the wings, and the latter that it was "doubtless produced by the sudden expansion of his capacious mouth." I am inclined to the opinion of Audubon in this matter.

Among our native-born Americans I have never heard the name of goatsucker applied to our whip-poor-will, whereas that is a very common appellation for the species in many parts of Europe, where still all manner of crimes are accredited to this very harmless bird—that is, to its European congener. It is now, of course, an old story that long, long ago the goatherds of Italy and Greece, observing those birds at dusk flying around the goats among their hilly pastures, and associating this fact with the known gaping mouth of a Caprimulgus, soon put the scandal on foot that they suck the teats of the animals, and thus rob them of the milk. That ancient philosopher Aristotle also believed the story, and enlarged upon the legend when he wrote that the "bird called ægothelas is a mountain bird, a little smaller than the cuckoo. It lays two or three eggs, and is of a slothful nature; flying upon the goats, it sucks them; they say when it has sucked the teat it becomes dry, and the goat becomes blind."

That charming naturalist White, of Selborne, did much toward breaking down this kind of rank superstition, informing us, as he has, that "the country people have a notion that the fern owl, or churn owl, or eve jay, which they also call a puckeridge, is very injurious to weanling calves, by inflicting, as it strikes at them, the fatal distemper known to cow-leeches by the name of pucker idge. Thus does this harmless, ill-fated bird fall under a double imputation which it by no means deserves: in Italy, of sucking the teats of goats, whence it is called the Caprimulgus, and with us, of communicating a deadly disorder to the cattle. But the truth of the matter is, the malady is occasioned by a dipterous insect, which lays its eggs along the chines of kine, where the maggots, when hatched, eat their way through the hide of the beast into the flesh, and grow to a very large size." Another name for this European goatsucker (C. europæus) is the "nightjar," and a popular writer on the natural history of the class thus accounts for its origin: "The jarring sound, which gives name to the bird, is uttered sometimes while flying, but usually when it is at rest; it seems to be produced in the same manner as the purring of a cat, and resembles it, though much louder. One of them, emitting this sound while sitting on the cross of a small church, communicated a sensible vibration to the whole building." (I doubt that that story will find many believers among us at the present day!)

If the accounts of the habits of such gentle creatures, as recorded by men, have passed, in time, through the various stages of traditional superstition, myth, and inaccuracy, to one of enlightenment, fact, and exactness, it has been none the less so with the various ideas of natural historians in the matter of their opinions as to the place occupied in the system by the Caprimulgi. One chapter is quite as full of interest as the other. More intelligent observation has cleared and is clearing away the mist that enshrouded the first, while this, combined with modern methods of scientific research, is rapidly rectifying the latter. Erroneous classification, in other words, is being corrected through the steady progress of our knowledge of the morphology or structure of the class Aves. From an evolutionary point of view such changing taxonomical advances stand among the most engaging of all lessons to the philosophic ornithologist. External appearances, it has taught among other things, are by no means a safe guide to the orderly classification of any series of objects. Some old works upon my library shelves, formerly considered "standard" and "classic," contain many chapters in those premises which are highly instructive on this point. One of them now open before me places, according to its author, such utterly diverse bird-groups as the trogans, the kingfishers, the swifts, the goatsuckers, and the humming birds, all among the Passeres. Linnæus and a number of his successors had no better appreciation of the truth, for the scientific light shed over such fields was to them still quite dim. He placed, with all confidence, the Caprimulgi in his order Passeres. Later, this created the usual intelligent, incredulous smile of the scientific taxonomer, and in the next epoch we find in their writings an "order" created to contain, among other types, the swallows, the swifts, and the goatsuckers! Then, too, think of Huxley, who as late as 1867, upon osteological grounds made a division Cypselomorplhæ, to which he restricted the swifts, the humming birds, and the goatsuckers. A decision of that kind coming from such an influential quarter has carried with it the weight of conviction to the minds of our most recent ornithological writers and systematists. And we find Elliott Coues, in his last revised edition (1890) of his Key to North American Birds, still adhering to the old order Picariæ, in the first group of which, the Cypseliformes, he places the swifts (Cypselidæ), the goatsuckers (Caprimulgidæ), and the humming birds (Trochilidæ). But a far more unnatural grouping is seen in the Manual of North American Birds, by Mr. Robert Ridgway, where an order Macrochires is retained to contain the goatsuckers, the swifts, and the humming birds, and in this he is followed by the check list of the American Ornithologists' Union. What special kinship the systematist sees between a humming bird and a whip-poor-will, the morphologist in these days certainly fails to appreciate. Anatomically the writer has examined in great detail several species of different genera of both humming birds and goatsuckers, as he also has many swifts and swallows, and is of the opinion that the Caprimulgi are most nearly related to the owls, while the swifts are but profoundly modified swallows. To thoroughly appreciate such affinities it is necessary that we should have before us the so-called "outliers" of the various groups just named.

Representatives of the suborder of birds, United States species of which we are here considering, are found in many parts of the world, though they appear to be entirely absent from the avifaunæ of Polynesia and New Zealand. In South America, in Asia, in Africa, and in Australia we meet with goatsuckers of the most varied kinds, both in the matter of form and plumage. One of the most evident types exemplifying the kinship between the Caprimulgi and the owls is the extraordinary species found in the caves of Caripe in South America and in Trinidad. This is the well-known "oil bird," the Steatornis caripensis of science, and also called the guacharo by the natives, who enter every season the caves where it breeds to collect the young. This is done to obtain the grease by trying out their fat-laden bodies, and thus the species has a certain economical importance. In its structure Steatornis is much like some owls, and its two to four white eggs, laid

PSM V44 D324 The whip poor will a vociferus.jpg
Fig. 2.—The Whip-poor-will (A. vociferus)♂. Drawn by the author and much reduced.

in a nest built by the bird of clay, closely resemble the eggs of certain birds of that group. Likewise it is nocturnal in habit, and markedly differs from the average goatsucker inasmuch as it feeds upon fruit and certain oily nuts. Structurally it has been examined with some care by the British anatomist Garrod, who fully appreciated its relation to the owls. Well it may be said that most owls have long legs which they can use to full advantage, which our night hawks and whip-poor-wills do not possess, those members being so short in them that they can only shuffle over the ground with difficulty. Yes, but there is also a Central and South American species of goatsucker, with legs so long that it can run upon terra firma with all the swiftness and ease of one of our peculiar little burrowing owls of the Western prairies (Speotyto). Again, it is said that such owls as our screech owls (Megascops) exhibit a dichromatism of plumage, being "rufous" in one and, when adult, "gray" in the other, and that they have "ear tufts" or plumicorns ornamenting their heads. Here it is interesting to know that in the Malay Archipelago and in China we meet with the goatsucker Lyncornis, which is also characterized by the possession of "aural tufts" and a dichromatism of plumage—the same species having been taken in both a rufous and a gray one. And so we might pass from one species to another, gathering one habit here, and another point in anatomical structure there, until the most skeptical person in the world would at last be convinced that the two groups (Caprimulgi and Striges) were in some strange way related.

Plumicorns are also possessed by the remarkable Indian caprimulgine bird Batrachostomus, a species which also occurs in the Malay Archipelago, and still other very curious genera of other parts are the Nyctibius and Ægotheles and Podargus; Podargus cuvieri being fully three times as large as any known North American species of goatsucker, being found in the island of Tasmania, where its peculiar cry has caused it to receive the name of "morepork" by the colonists of that distant quarter of the globe. But for the greatest oddities among these birds, especially in the matter of plumage, we must turn to Africa, and that paradise for the explorer, Madagascar. For instance, the Macrodipteryx of Africa has the ninth primary feather of either wing developed to a pennant-like length, and when the bird is seen during flight these appendages float out in the most striking manner; being still more peculiar in an allied species where the shaft of these elongated feathers is naked, and it is only at their extremities that a spatulate form of the web is retained. Madagascaran species exist that even have still more remarkably developed wing feathers, while in the South American Psalurus, again, it is the lateral tail feathers that are greatly lengthened.

In concluding this brief paper I would invite attention to the fact that we find the family of goatsuckers immediately following the family of owls in Audubon's Birds of America, and of the former he observes that they are "very nearly allied in some respects to the owls"; and I am strongly inclined to the belief that that "careful dissector of birds," the "Scotch anatomist" William Macgillivray, had much to do with bringing the mind of our distinguished Franco-American ornithologist to that opinion.