428 U. S. NATIONAL MUSEUM BULLETIN 211 



Of the arboreal display, which is the commonest and best known, 

 Friedmann writes: 



The display is often, but not always, begun by the bird pointing its bill toward 

 the zenith. This is usually done whenever another bird, especially another male, 

 is very close to the displaying bird. Next it fluffs out the feathers of its hind 

 neck, breast and sides and flanks. * * * It is during this part of the display that 

 the bubbling guttural notes are given. Wetmore has written it bub ko lum and 

 I cannot improve on his description. These notes are quite low and not audible 

 in the field at a distance of more than fifty feet. During this stage of the per- 

 formance the bird sometimes rises and falls gently on its legs in a vertical direc- 

 tion, the rise hardly ever amounting to as much as the length of the tarsus. 



After this the bird begins the display proper by arching its neck and spreading 

 its tail * * *. Then it begins to raise its wings and bend forward * * *. All 

 this time the feathers of the back are fluffed out just as are those of the under- 

 pays. Then the wings are brought out to their full expanse * * *, and the 

 toppling over proceeds from now on with accelerated rapidity, the tail being lifted 

 before the body pivots and swings over. * * * The display ends when the 

 wings are brought back to the body * * *. The bird then rights itself and is 

 ready to repeat the whole performance. [See plates 28 and 29.] 



The entire display lasts about three or four seconds and the tseee note [see under 

 "Voice"] usually has a duration of about a second or a little over. The frequency 

 of display is extremely variable. I have seen a male display with almost clock- 

 like regularity at intervals of five seconds for several minutes when no female was 

 in sight, and I have also watched a male display once and not do it again for over 

 an hour. Display becomes less and less frequent as the season wears on and is 

 usually not indulged in to any extent after the middle of June, while song continues 

 until a month later. Those displays that are given after the middle of June are 

 usually incomplete. This incomplete display consists of spreading the tail, 

 hunching the back and slightly arching the wings, but the bird does not fall for- 

 ward. 



A male bird, observed by Wetmore (1920) in New Mexico, "would 

 sit quietly for a few seconds, then expand the tail and draw the tip 

 slightly forward, erect the feathers of the back and to a less extent 

 those of breast and abdomen, and then sing bub ko lum tsee. In 

 giving the first three notes he rose twice to the full extent of his legs 

 and sank back quickly." 



C. J. Maynard (1896) describes the courtship flight as follows: 



Two or more males often pay their attentions to one female, singularly, without 

 attempting to quarrel, when she will suddenly take wing and all will start in 

 pursuit. The flight of a female at this time is exceedingly swift, for she will 

 usually manage to keep ahead of her followers who ardently press on, giving a 

 rather sharp, prolonged cry as they dart through the air. All the males within 

 hearing join in, and it is not unusual to see a half dozen at a time after one of the 

 other sex who will lead them a long chase, now darting upward to a considerable 

 height, then doubling, will glide through the tangled branches of a clump of trees, 

 emerging on the opposite side with great rapidity. This exciting race is evidently 

 maintained merely as a matter of sport, for when the object of chase becomes 

 weary she will quietly settle on the branch of a tree, and her admirers gather 

 around her, calmly arranging their feathers. After resting for a time one will 



