1626 U.S. NATIONAL MUSEUM BULLETIN 237 part 3 



mainly responsible, although the activities of the ground squirrels 

 were restricted entirely to the gravel-covered stream bottoms where 

 longspurs were relatively scarce. 



After the young leave the nest they are particularly vulnerable to 

 avian predation, and at Cape Thompson two species of jaegers, the 

 parasitic and the long-tailed, feed on them regularly. James W. Bee 

 (1958) reported that he observed short-eared owls and pigeon hawks 

 preying regularly on longspurs in the vicinity of Point Barrow, 

 Alaska. I watched a northern shrike capture and kill a young long- 

 spur in Mt. McKinley National Park. 



Heavy precipitation at the time of hatching caused many nest 

 losses at Cape Thompson. In 1961 rain associated with wind and low 

 temperatures fell June 14 to June 21 following the peak of hatching on 

 June 13. In the 66 nests under observation, 10 nest losses resulted 

 from this storm, while only one before and one after that period were 

 attributed to weather. Considering the relatively small number of 

 nests I was able to observe, the loss must have been very great on a 

 regional basis. At such times the females brood the young effectively 

 for a while, but nevertheless must leave to feed, and frequently the 

 resulting exposure is sufficient on a cumulative basis to cause losses of 

 young. By contrast, in 1960 with 46 nests being watched, only one 

 nest loss was attributed to the heavy rain that fell June 19 to 27, 

 apparently because the young birds were by then sufficiently well 

 feathered to endure the sporadic absence of the female. 



Stormy weather is a well-known peril for migrating passerine birds, 

 and the Lapland longspur is no exception. T. S. Roberts (1932) 

 describes a spectacular mass kill in Minnesota during a March snow- 

 storm in 1904: 



On two small lakes, with an aggregate area of about two square miles, the ice 

 was still intact and nearly bare from the melting snow. This exposed surface 

 was thickly and evenly strewn with dead longspurs. By measuring a number of 

 squares, counting the birds in each, and averaging these counts, it was possible 

 to make a fair estimate of the number of bodies on the whole area. A conservative 

 calculation showed that there were at least 750,000 dead longspurs lying on these 

 two lakes alone! The adjoining uplands, the streets of the town, and the roofs 

 of the buildings were strewn with bodies in equal numbers. And this was only 

 one locality in the extensive area throughout which the birds were killed. 



Roberts adds that the total area involved was found to be approxi- 

 mately 1,500 square miles. This mass mortality had no noticeable 

 effect on the numbers of migrating longspurs in succeeding years. 

 With respect to such winter kills Lincoln (1939) writes "Almost 

 every winter brings reports of storm destruction of thousands some- 

 where in the Middle West until it seems amazing that the species 

 is able to survive * * * catastrophes have been reported from eastern 

 Colorado, Nebraska, and North Dakota." 



