KNOWLEDGE. 



[January, 1903. 



been celebrated for its remarkable love display. Collecting 

 in small parties of l)oth sexes, tiie males come forward and 

 perform a series of stran<je evolutions, in which a pair of 

 sass, one on either side of the neck, play a conspicuous 

 part. When the bird is quiet these sacs or bags are 

 hidden by the feathers, but during the paroxysms of 

 excitement they are inflated so as to form a pair of huge 

 bladder-like organs, of a bright orange colour. As soon 

 as these pouches are filled certain elongated feathers of 

 the nape of the neck are shot forwards, the winQ:s are 

 trailed upon the ground like thcise of the turkey-cock, and 

 the body, with the feathers bristling like the quills of the 

 fretful porcupine, is inclined forwards. Suddenly the bird 

 starts to run, rushing in among the amazed females and 

 giving voice at the same time to a loud booming noise, 

 audible, on a still morning, for a couple of miles. Then 

 follows a momentary period of quietude, and the process 

 is repeated. Sometimes as many as twenty cocks take 

 part at a time in these displays. 



The depletion of our British bird-fauna which has taken 

 place daring the last fifty years has robbed us at one fell 

 stroke of our largest British bird, as well as the only nember 

 thereof which boasted a true ornamental air-sac. This was 

 the great bustard To witness the display of this bird in 

 a wild state to-day one must travel to Spain. To the 

 bird-lover the journey is well worth the making, for a more 

 wonderful, and at the same time a more grotesque sight, 

 would be hard to find, since the inflation of its wind-pouch 

 is accompanied by the art of the contortionist. 



Approaching his mate with a series of short, mincing 

 steps, he next proceeds to throw his tail forwards so as to 

 lie flat upon his back, where it is held down by the long 

 quills of the wing. Thus he contrives to display a 

 magnificent, billowy mass of white feathers which normallv 

 lie under, and are concealed by the tail. Next he ruffles 

 up the feathers of the back and wings in such a wav that 

 certain feathers forming the inner lining of the wing are 

 brought prominently into view ; these also are white 

 as the driven snow. Finally the head is thrown back, 

 and the wind-pouch or air-sac as it is called, is 

 inflated to an enormous size, almost burying the head 

 therein This done, the head is .■still further masked by 

 the erection of a number of long feathers, which normally, 

 when the bird is at rest, hang down like a long beard. 

 Erected, they stand up on either side of the head like a 



Fio. 1. — The display of tlie Groat Bus-tard, Otis tarda. 

 (After AVolf.) 

 From tile *' Dictionary of Birds," by Prof. A. Newton. 



palisade. What the general effect of such a displav is like 

 may be gathered from the annexed^ picture. 



This air-sac deserves further notice, for it is a peculiarly 

 interesting structure both from an anatomical and a 

 historical point of view. 



Well known to the older naturalists, it was generally 

 regarded by them as a receptacle for water, a view which 

 gained colotir from the fact that the bird frequented 

 arid and sandy wastes where water was naturally scarce, 

 so that the possession of a water-bottle seemed by no 

 means a striking feature. This tradition, in more critical 

 times, first became suspect by the discovery that the 

 male only possessed the pouch. Further enquiry showed 

 that not even all the males were so provided, and this led 

 many to believe that the whole story of the existence of 

 the pouch at all was a myth. If its use was to store water, 

 they contended, it should be found in both sexes, since 

 both would have equal need thereof. The fact that many 

 adult male birds had been dissected without revealing the 

 presence of a pouch seemed to confirm their doultts as to 

 the probability of the story. 



Later observation, however, has definitely settled the 

 question. Careful dissection has proved the existence of 

 the pouch, whilst the field naturalist has shown us its 

 purpose, which turns out to be ornamental rather than 

 useful. 



Structurally, this air-chamber or wind-bag, as it proves 

 to be, differs, as we have already hinted, from those which 

 have so far been described, inasmuch as these have been 

 formed simply by inflation of the food-pipe or gullet, 

 whilst in the case of the bustard the chamber is an entirely 

 independent structure. Extremely thin-walled, it extends 

 from the base of the tongue down the front of the neck, 

 immediately beneath the skin, to its base. In fully- 

 developed examples this remarkable pouch is found to 

 have a bulb-shaped termination, the which lies between the 

 arms of the merry-thought. Air is admitted through a 

 small hole at the base of the under-side of the tongue, and 

 when the display of the proud performer is finished, the 

 air is expelled again from the same aperture. During 

 the display small quantities of air appear to be expelled 

 for the purpose of producing a sound said to resemble the 

 word " oak," possibly to attract the attention of the lady 

 of his choice, who often affects an absolute indifference or 

 even ignorance of the fantastic performance which is 

 intended for her eyes alone. 



Some doubt still exists as to whether this pouch is 

 retained throughout the year, or whether, after the season 

 of courtship, it becomes absorljed to be re-developed in 

 the succeeding spring. 



It seems but natural to suppose that the method of 

 courtship displayed by the great bustard would be adopted 

 by the bustard tribe in general. As a matter of fact, 

 however, such is bv no means the case. No other bustard 

 has succeeded in attaining such a pitch of artistic display. 

 The nearest approach thereto, perhaps, is that made by the 

 giant Australian bustard, Enpvdotis audrnhs. But he has 

 not the skill of his British cousin. His attitude at this 

 time is distinctly " wooden." Throwing the tail upward 

 and forward over the back, the neck is then stretched to 

 its greatest length and held stiffly upwards, whilst at the 

 same time great gulps of air are drawn into the gullet till 

 a long pendulous and feather-clad bag is produced which 

 hangs down considerably below the level of the breast. 

 At the throat is a great bulbous swelling which causes the 

 feathers in this region to stand on end, and therel)y add 

 to the effectiveness of the whole display. The attitude 

 complete, the ardent swain stands motionless, mutely 

 pleading for the approval of his prospective mate. Here 

 again, be it noted, no special apparatus, no true air-sac or 

 wind-bag has been produced. The same methods have 

 been resorted to which are employed by the frigate-bird and 



