Michigan Ornithological Club 15 



have only met \vith the opinion of two authors who have attempted to indi- 

 cate the spring route of migration. Chapman ('99, p. 290) says : "Thus 

 during the winter Kirtland's Warbler apparently ranges throughout the 

 Bahamas, having been found from Caicos to Abaco, though it has not 

 as yet been recorded from Inagua. Its northward migration begins in April, 

 South Carolina being reached toward the end of the month, either by direct 

 flight from the Bahamas, or, what is more probable, by advancing northward 

 along the Southeast Atlantic Coast (St. Helena April 29, Worthington). 

 This is the most northern, spring cis-Alleghanian record, the migratory 

 route of the species now leading it northwestward into the Mississippi 

 Valley." 



The other author referring to the Spring route is Butler ('97, p. 1072) 

 who says : "The line of its spring movements seems to be a narrow route 

 from the Bahamas past the western end of Lake Erie toward Lake Superior." 



It is unfortunate that so little is known about this bird south of the 

 Ohio river. The above quotations clearly emphasize this lack of data and 

 show the desirability of further light upon this subject. 



After coming to Ann Arbor jSIr. A. B. Covert called my attention to 

 this bird and its relative abundance in this locality, four specimens havings 

 been taken here. And being familiar with the idea of migration routes T 

 was led to infer that Ann Arbor was located on such a route. This idea 

 seemed to be in harmony with the fact that the number of birds recorded 

 from here is not due to the relative numbers of collectors in the field, because 

 only two specimens have been recorded from the vicinity of Chicago, with 

 its nuich greater number of collectors, but to its favorable location on an 

 important migration route. 



The geographically scattered records of Kirtlandi suggested to me the 

 similarity of their occurrence to that of stragglers of other species and the 

 routes followed by such birds. For example, in southern Michigan the 

 Prothonotary Warbler is generally speaking rare, although it breeds in 

 abundance along the St. Joseph river in the southwestern part of the State 

 Stragglers have been found elsewhere in the State and have been known to 

 breed, but in general there is a definiteness in the occurrence of these 

 stragglers, as will be seen later. The similarity of this straggling phen- 

 omena to the occurrence of the migrant Kirtland's suggested to me a pos- 

 sible analogy in the migration routes of the two species. The farther this 

 comparison was carried the more significant it appeared to become. Louck's 

 paper ('95) on the geographical distribution of the Prothonotary Warbler in 

 Illinois and Lidiana has been used as the basis for the comparison, supple- 

 mented by a few other records. But in order to understand this com- 

 parison some of the general facts of the distribution of the Prothonotarv 

 Warbler must be fresh in mind. For this reason I have adapted and 

 supplemented Louck's map of this species to show especially the occurrence 

 of stragglers and isolated colonies. An examination of the map w^ill show 

 how closely this swamp warbler is restricted to the streams. Tn addition 

 to the shaded area in which it is known to breed regularly, it occurs also 

 as a .*;traggler in the northivard eontimiatious of the same valleys, as indi- 



