204 BULLETIN 14 6, UNITED STATES NATIONAL MUSEUM 



an hour during the coldest weather." M. P. Skinner of the Yellow- 

 stone Park writes : "Although the killdeer is not a song bird I have 

 heard some quite musical notes and even tuneful sequences from him. 

 On the 4th of April one was heard singing while flying low in a 

 circle over the nesting ground, and the performance was strongly 

 suggestive of a nuj^tial flight song." 



S. F, Eathbun of Seattle has communicated the following interest- 

 ing account of his observations on the subject : 



The evolutions were participated in by both birds of the pair that I watched 

 on several occasions, and, as my knowledge goes, very early in spring prior to 

 nesting. At this time these birds were evidently mated. As they fed about 

 the margin of a small pond, one invariably following the other, suddenly the 

 bird in the lead would spring into the air and mount upwards by a succession 

 of wide, sweeping spirals, with its mate in pursuit constantly uttering its notes 

 in a short and hurried manner. Higher and higher was the flight, but restricted 

 over the certain area of the pond until both disappeared from one's vision, 

 although the note continued to be faintly heard. As I continued to watch, the 

 birds' cry ceased and down from the sky I first noted a speck falling, then 

 both came into plain sight, one following the other, and then both alighted. 

 This descent was as quickly made as if the birds fell out of the ether. After 

 alighting the former actions were again indulged in, and shortly after the 

 high flight was again made. These actions were repeated several times during 

 my stay of over two hours in the vicinity. 



From these reports it is evident that the courtship flight is per- 

 formed in various ways, and, as Audubon (1840) says, " It skims 

 quite low over the ground, or plays at a great height in the air, par- 

 ticularly during the love season, when you may see these birds per- 

 forming all sorts of evolutions on the wing." 



Of courtship display on the ground Theed Pearse (1924) writes: 



On two occasions that I saw one getting up he ran a short distance and then 

 went through what looked like a sexual display. Crouching on the ground 

 and leaning toward one side with wings lowered and then opening the tail in 

 fan shape over the back so that the cinnamon tail coverts came conspicuously 

 into view, at the same time uttering a trilling note. 



Aretas Saunders (1926) thus describes the display: 

 Two birds would crouch side by side but facing in opposite directions. Then 

 they would droop the tips of the wings so that they exposed the ochraceous 

 patch of the lower back, spread the tail, and tip the breast forward, slowly 

 lifting the wing tips till they came way above the back, but never covered it 

 from view. All the while they kept up a continual call, the long-trilled note 

 t-r-r-r-r-rrrrr. The displaying birds would often begin the performance or end 

 it with a little fighting. 



Ira N. Gabrielson (1922) reports a case where — 



the male had taken his station some distance from the female and at intervals 

 whirled rapidly about, uttering a curious stuttering note as he did so. Every 

 few seconds the female advanced a few steps toward the male, but when he 

 stopped to observe the effect of this display she quickly turned her back and 



