GREENLAND WHEATEAR 301 



in Keewatin, Ontario, New Brunswick, Quebec, New York, Pennsyl- 

 vania, Louisiana, Bermuda, and Cuba." 



The wheatears are characteristic Old World birds, having a wide 

 Palearctic distribution, in which there are several Eurasian forms. 

 The species has extended its range into the northeastern corner of 

 North America in the form of the Greenland wheatear, and into the 

 northwestern corner in the form of the typical wheatear of Europe 

 and Asia. Neither form, though both are more or less established as 

 breeding birds at the two extremities of Arctic North America, has 

 established any regular migration route on this continent. The steps 

 which led up to the discovery of the two migration routes and the 

 separation of the Greenland subspecies have been fully explained in 

 an interesting paper by Dr. Leonhard Stejneger (1901), to which the 

 reader is referred. He gives the diagnostic characters of the Green- 

 land bird as "larger than Saxicola oenanthe, the length of wing vary- 

 ing between 100 and 108 millimeters; color similar, but the rufous 

 tints more bright on the average." The wing measurement of the 

 typical subspecies seldom equals 100 millimeters and is usually much 

 less. 



He adds the following comments on the strange distribution and 

 probable expansion of range of this interesting species into the Nearctic 

 region: 



The Wheatear, the most widely distributed species of the genus Saxicola, thus 

 extends its range across the entire palaearctic continent from the Atlantic to the 

 Pacific Ocean. At both extremities of its home continent, however, it has ex- 

 panded its range into the New World, and no one who follows on the map the 

 route of the retreating winter migrants can for a moment be in doubt that these 

 routes really represent the way by which the species originally invaded America. 

 It would be difficult to find a more beautiful example to illustrate that now 

 well-known law which was first formulated by Prof. Johan Axel Palmen, of Hel- 

 singfors. Moreover, no better example could be found for demonstrating the 

 necessity of minute discrimination in ascertaining the characters by which these 

 "migration route races," as Palmen calls them, are characterized. 



It seems that one more lesson can fairly be drawn from the differentiation of 

 the Greenland race, viz, that the Greenland-Iceland-England route must be con- 

 siderably older than the Alaska-Tchuktchi-Udski route, since it has resulted in the 

 establishment of a separable race. A consideration of the further fact that no 

 regular migration route could have been effected between Greenland, Iceland, and 

 Great Britain during the present distribution of land and water in that part of the 

 world also leads us back to a period when the stretches of ocean now separating 

 those islands were more or less bridged over by land. For such a condition of 

 affairs we shall have to look toward the beginning of the glacial period. At that 

 time it must, therefore, be assumed that the Wheatear extended its range into 

 Greenland. The advent of the typical form into Alaska, on the other hand, is 

 probably one of very recent time, an assumption corroborated by the somewhat 

 uncertain and erratic distribution of the species in that northwestern corner of our 

 continent. 



