88 THE MIGRATIONS OF BIRDS 



dom individuals may be found in cities^ towns, or 

 other untoward neighborhoods. With others that 

 seem equally sedentary it appears that there may be 

 true migration in greater or less extent. What move- 

 ment there may be in central latitudes among such 

 species as meadowlarks, song sparrows, flickers, 

 robins, and many others that are present through 

 the year, is as yet purely a matter of speculation. 



Many insular birds appear wholly sedentary, in 

 that there is no interchange of individuals between 

 islands which often lie within sight of one another 

 and are easily reached by moderate flights. In east- 

 ern Porto Rico a species of crow {Corvus leucogna- 

 phalus) is found in forested areas, but makes no 

 attempt to cross to the island of Vieques, in plain 

 sight only fourteen miles away. Bones of this species 

 are known from St. Croix, indicating that it was 

 found there in ancient times, but it has never been 

 reported there as a living bird by modern natural- 

 ists. Still more strange is the case of a land-rail 

 (Hypotaenidia wakensis) found on the isolated island 

 of Wake in the Pacific Ocean between Guam and 

 Honolulu. The atoll at Wake has three islands, 

 arranged in the form of a horseshoe surrounding a 

 broad lagoon, separated from one another by nar- 

 row channels not more than loo yards wide. The 

 rail is found on the northern and eastern islands but 

 does not occur on the one to the southwest. That 



