1638 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 3 



after one another in undulating flight high above the fields, then 

 dropping back to then* own territories. 



Occasionally a much more violent chase takes place, apparently 

 when a male bird discovers a trespasser on the ground within his 

 territory. He flies at the offending bird and chases it in a fast, erratic 

 course low over the ground until he has driven it well away from his 

 boundaries. 



Fights occur frequently along territorial boundaries. Two males, 

 each probably on his own territory, may be foraging only a few feet 

 apart. Suddenly one of them, possibly considering the other to be 

 trespassing, runs at him with lowered head. Facing each other, the 

 two join battle with fluttering wings. They may rise together to 

 a height of 4 to 15 feet before dropping separately to the ground, 

 either to go their own ways or to start the fracas again. I have never 

 seen a bird hurt in these exchanges. 



We experimented with setting up a mounted male chestnut-collar 

 about 50 feet from an active nest. The male first threatened the 

 dummy. Facing it with his head held high, he pointed his bill up at 

 a 45-degree angle and raised his breast to show as much of the black 

 as possible. He then dived repeatedly at the interloper, delivering 

 blows to the head and back. Such continued chastisement would be 

 unlikely under natural conditions where the intruder would retreat 

 or fight back. 



Courtship. — Courtship in the chestnut-collared longspur seems 

 largely a matter of staying close together. Up to the time incubation 

 starts, when the male isn't singing we can usually find the pair forag- 

 ing together quietly in the more open parts of their territory. We 

 saw a number of sexual chases, in which the male chased the female 

 low over the prairie in fast, erratic flight, apparently trying to force 

 her down. After a minute or so the male was seen to fly back to the 

 foraging area, the female following along behind. As Tinbergen 

 (1939) found with snow buntings, these chases probably result from 

 the male's unsuccessful attempt to copulate when the female is not in 

 the right state of physiological receptiveness. The only display 

 we saw a male make under natural conditions was to lift the tail 

 high over the back momentarily on two occasions. 



That a much more intense display is possible was shown by a male's 

 reaction to a mounted female placed near the nest. Approaching 

 the dummy female in a zigzag course, he erected his chestnut collar, 

 stretched his head high, and looked down at her over his lowered bill 

 from directly in front. He then fluttered to her back and attempted 

 to copulate. Dismounting, he ran away from her holding his body 

 level with the ground, wings and wide-fanned tail almost drag- 

 ging. He then circled back and tried once more to copulate, dis- 



