WESTERN BURROWING OWL 393 



Enemies. — Burrowing owls have few natural enemies, though rattle- 

 snakes doubtless destroy some eggs and young. Dr. J. F. Brenckle 

 suggests in his notes that the nests may sometimes be invaded by cats 

 and says that "the highway seems a favorite feeding ground, and, 

 with the bright lights and speed of cars, many are killed or wounded." 

 Undoubtedly many are killed by the indiscriminate use of carbon 

 disulphide in campaigns against ground squirrels; no distinction is 

 made between the holes occupied by squirrels and those in which the 

 owls are nesting; all the holes are poisoned and sealed, thus killing 

 many a family of owls, the farmer's best friends. 



Migration. — Throughout the more northern portions of their range 

 burrowing owls are more or less migratory. Bendire (1892) says: 

 "In Washington, Idaho, and Oregon, they appear to migrate about 

 the beginning of November and sometimes earlier, returning to their 

 summer homes in the early part of March. At any rate, without 

 actually examining any of their burrows during the winter months, 

 to ascertain their presence, I never saw one of these birds, as far as I 

 can remember, sitting in front of these at such times, and I have lived 

 where they were very common and certainly would have noticed one 

 occasionally if actually about." 



Dr. J. F. Brenckle, who has banded some 300 burrowing owls near 

 his home in North ville, S. Dak., has sent me some interesting notes on 

 his returns. Many of the returns were of birds killed on highways at 

 nearby points, and one was killed on a railroad track. Of the more 

 distant returns, one was found wounded on a highway near Royal, 

 Nebr., on October 1, 1931; one was captured at Gunter, Tex., on 

 January 7, 1932; one was taken at Edmond, Okla., on December 12, 

 1932; and one was captured at Willow, Okla., on April 4, 1933. Evi- 

 dently some of these owls indulge in extensive migratory movements. 



Winter. — Apparently some of these little owls remain on their 

 northern breeding grounds all winter, for Dr. G. S. Agersborg (1885), 

 referring to "southeastern Dakota", says: "In the winter as many as 

 twenty of these birds may be found nestling together in one hole. 

 They are always at such times abundantly supplied with food. I 

 have found at one time forty-three mice and several Shore Larks 

 scattered along the run to their common apartment. They forage in 

 fine weather and retreat to their dirty adobes when cold weather 

 threatens." 



Dr. Coues (1874) quotes Townsend as saying: "I found both the 

 prairie-dogs and the Burrowing Owls abroad and very active on pleas- 

 ant days in December and January, on the plains of Western Kansas, 

 although the temperature often fell nearly to zero (Fahrenheit) during 

 the nights following. I was also assured by old residents of the plains 



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