1594 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 3 



at him repeatedly, sometimes actually striking his back." Adds 

 Mickey (1943), "On several occasions the birds were seen hovering 

 over a ground squirrel, chirping and darting at it in an effort to drive 

 it away from the nest site," suggesting that the birds recognize these 

 animals as predators. 



While the elements and the animal predators undoubtedly take a 

 yearly toll of McCown's longspurs, the species has been subject to 

 their onslaughts for millenia with little evidence of any serious 

 reduction of the population. The real threat, whether recognized, 

 minimized, or ignored, as DuBois (1936), states, is man — "man whose 

 poisoned baits set out for ground squirrels apparently kills more 

 birds than spermophiles." Man with his plow and his agricultural 

 achievements: "Many nests were of course plowed under by the 

 breaking plows of pioneer farmers," DuBois remembers. "I have seen 

 one or two go over with the turning sod, when it was too late to 

 prevent it." 



To DuBois' list of enemies Mickey (1943) adds the cat, the badger 

 (Taxidea taxus), and among birds the prairie falcon and western crow. 

 "A pair of Swainson's Hawks, Buteo swainsoni, and a pair of Marsh 

 Hawks, Circus hudsonius, were frequent visitors to this field. They 

 swooped over the field in search of rodents, quite indifferent to the 

 smaller birds. A Prairie Falcon, Falco mexicanus, occasionally visited 

 the field, but did not seem to bother the longspurs. Sometimes the 

 longspurs ignored the hawks, but oftener a group of buds would rise 

 and twitter noisily as they flew around the hawk. * * * Although I 

 did not actually witness any depredations by the crows, it is my 

 belief that they were responsible for the disappearance of some of the 

 eggs and young of the smaller birds." 



Frequently the forces of nature itself are antagonistic. Unseason- 

 ably cold rainstorms and late spring snows often bring disaster to 

 the young of McCown's longspur. DuBois (1937a) describes a 

 Montana storm that brought a deep fall of snow on May 25 and 

 continued into the 26th. 



I had previously marked a nest in which the bird was known to have begun 

 incubating her four eggs on the morning of the 19th. The snow covered every- 

 thing so completely that I could not find my marker; but in the afternoon of the 

 26th the marker-rock showed through the melting snow, and I uncovered the 

 nest. The eggs had been in cold storage all of one day and part of another; 

 but an hour or two after the nest was uncovered the female was sitting on the 

 eggs. She continued to incubate until the 8th of June. That day she was absent 

 morning and evening, though in the nest at noon. Before my return early the 

 next morning the eggs and nest had been mysteriosly destroyed. The bird had 

 continued incubation about nine days beyond the normal period. Perhaps it 

 was her first experience with eggs under snow. 



