152 BULLETIN 191, UNITED STATES NATIONAL MUSEUM 



young ones and might have been captured more easily than old ones. 

 In a report on the food habits of hawks in Canada, Munro (1929) men- 

 tions the flushing of a goshawk from the still-warm body of a magpie. 



A special study of the invertebrate fauna of oc.cupied magpie nests in 

 Montana was made by Jellison and Philip (1933). The extreme in- 

 festations of the blood-sucking dipterous larvae of Protocalliphora 

 avium, which they observed, indicated that the large, twig-canopied, 

 mud-plastered, fiber-lined nests of magpies served as favorable habita- 

 tions and the nesting birds as excellent hosts. From five of the magpie 

 nests examined, 108, 187, 190, 343, and 373 larvae were taken, respec- 

 tively. The last was the greatest number reported to that time from a 

 single nest of any bird. Two hymenopterous parasites, Mannoniella 

 vitripennis (Walker) and Morodora armata Gahan, both chalcids, were 

 reared from the puparia. Larvae of the beetle Dennestes signatus Le- 

 Conte were observed to be predacious on the puparia of the flies. 



Blood-gorged midges, Culicoides crepuscularis Malloc.h, were abundant 

 in nests built close to a stream and seemed to be at home in the debris 

 of the nests. Two kinds of Mallophaga were taken from the nestlings, 

 Docophorus communis Nitzsch and Myrsidea eurysternum (Nitzsch). 

 Additional kinds of beetles found in the nests were: Dcrmcstcs talipiniis 

 Mannerheim, Anthrenus occidens Casey, Helops convexulns LeConte, 

 and Cratraea sp. 



Migration. — The migratory habit is developed to different degrees 

 in the various kinds of magpies, but nowhere is it well marked. In the 

 southern part of the range the birds move scarcely at all. Farther north 

 they migrate, sometimes great distances, but always probably in im- 

 mediate response to severe winter c.onditions. In the United States fall 

 and winter movements are noted regularly within the general range of 

 the bird, and in some years well-defined migrations occur outside that 

 range. 



In many parts of the range of the black-billed magpie local move- 

 ments of the birds may be detected in fall, usually in September. On the 

 Taku River, Alaska, in the latter half of September, Swarth (1911) 

 observed numerous flocks of eight or ten individuals flying from the 

 interior out toward the coast, where they spent the winter. The same 

 observer (1926) reported a similar migration, also in September, in 

 northern British Columbia. Fall dispersal of magpies was detected from 

 August 28 to late in September by Taylor and Shaw (1927) on Mount 

 Rainier. 



The return to the interior takes place early in spring by way of the 

 major passes through the mountains. In one example, cited by Dawson 

 (1909), D. E. Brown saw, on March 4, several bands of magpies passing 



