182 BULLETIN 142, UNITED STATES NATIONAL MUSEUM 



they worked out into comparatively deep water where in feeding it is necessary 

 to immerse the head over the eyes nearly to the ear openings. When dis- 

 turbed flocks rose with soft notes that resembled tseet tsect or tscup to circle 

 to new feeding grounds on the lake shore. 



The spring migration route is apparently northward along the 

 Atlantic coast of South America and through the West Indies to 

 the United States. Only a few migrate along our Atlantic coast, 

 as the main flight is northward through the interior, during May and 

 the first few days of June. Many reach their breeding grounds 

 before the end of May. 



Courtship. — Doctor Wetmore (1926) gives an attractive account of 

 what seems to be a beginning of courtship in Argentina; he writes: 



Occasional parties of males, animated by the approaching breeding season, 

 broke into soft songs and called and twittered, often for several minutes, in 

 a musical chorus in low tones that had so little carrying power that they 

 merged in the strong wind, and it was some time before I succeeded in picking 

 out the sweet individual songs tsep a tscp a tsep a or twee twee tee tee ty tee 

 given as the head was bobbed rapidly up and down. Occasionally when the 

 fall sunlight came warmly I sat in the mud and let little bands of white rumps 

 work up around me until they were feeding and calling within a meter or so, 

 eyeing me sharply for any cause of alarm. At such times their twittering 

 choruses came sweetly and pleasantly, clearly audible above the lap of waves 

 and the rush of the inevitable winds of the pampas. Between songs the search 

 for food continued without cessation. At short intervals, activated by the 

 warmth of the sun, they suddenly indulged in dozens of combats with their 

 fellows, bloodless affrays, of bluff and retreat, where they lowered their heads 

 and with open mouths ran at one another pugnaciously. The one attacked 

 sidled quickly away or fluttered off for a short distance, save where two of 

 equal temperament chanced to clash when first one and then the other threat- 

 ened with raised wings in alternate advance and retreat until the fray was 

 concluded to their mutual satisfaction. At such (imes the movements of these 

 otherwise plain little birds were sprightly and vivacious to a degree. Their 

 loquacity at this season was marked as it contrasted strikingly with their 

 silence and quiet during the resting period of southern summer. Flocks fre- 

 quently rose to perform intricate evolutions and then returned with a rush to 

 sweep along the shore and join less ambitious comrades. As they passed the 

 white rump flashed plainly, certain advertisement of the species. At times 

 the chattering of these active flocks reminded me of the twittering of swallows. 



J. Dewey Soper found this species quite common at various places 

 on Baffin Island, and has sent me some very full notes on it, from 

 which I quote as follows: 



The species was encountered at Nettilling Lake, June 10, 1925, when a mated 

 pair was flushed from a marshy upland near the Takuirbing River. The sexual 

 organs in both were fully developed, the female being almost on the point of 

 laying. By the 14lh the species had become quite common. The males prac- 

 tised their vocal performance on the wing immediately upon arrival. They rise 

 to a height of about 60 feet above the tundra and there they hover with rapidly 

 beating wings giving utterance to their nuptial song in notes so weak that when 

 a wind is blowing nothing may be heard of it even at comparatively close 



