loo THE MIGRATIONS OF BIRDS 



is perhaps trite to state that the majority of acci- 

 dental visitors appear during the seasons when they 

 are in migration. The first group — those found 

 casually a short distance beyond their normal range 

 — may represent attempts at extension beyond pres- 

 ent boundaries, which, if successful, may result in 

 final establishment of a species in a new area. Dr. 

 J. Grinnell ^ has discussed this matter rather fully as 

 regards the State of California, and considers these 

 accidental occurrences as representing a trial and 

 error method whereby a part of the surplus of 

 the stock of any particular species pushes out into 

 new territory where it may be lost or may survive. 

 Wastage is severe, but is of small moment in the 

 working of the laws which through the ages control 

 distribution of millions of individuals. Again, these 

 accidental records may represent sporadic attempts 

 of a species to reestablish itself in regions from which 

 it has been forced to retreat. 



Of another kind are records of birds at points far 

 from their normal range, which are assumed to rep- 

 resent individuals that have wandered uninten- 

 tionally from accustomed paths through the agency 

 of storms or other untoward circumstances that they 

 have encountered. These may include strange visi- 

 tors of every description, sea-birds found far in- 

 land, land-birds blown at sea, or tropical and sub- 



^ /f«^,l922, pp. 373-380. 



