IRREGULAR MIGRATION 99 



be considered in this category of vagrants, since 

 they are regularly migratory toward the south, and 

 on occasion merely extend the length of their jour- 

 neys. Part of their journey is regular, though its 

 extent may be subject to variation. 



Casual Records 



The student of local avifaunas, intent on main- 

 taining a complete list of the birds of his region, with 

 notes on their abundance and occurrence, is al- 

 ways elated to detect the unusual visitor. Some un- 

 expected stranger well repays hours or days passed 

 in careful scanning of abundant birds of usual oc- 

 currence, whose habits and movements are wholly 

 familiar. A glance through any state list or compre- 

 hensive check-list reveals frequent instances of this 

 sort, and almost every number of the current maga- 

 zines dealing with ornithology records others. The 

 steady increase of record of such unusual occur- 

 rences is due to the steadily increasing number of 

 persons interested in observing birds — a factor that 

 submits the avian population to close scrutiny and 

 offers more frequent chance of detection of the 

 unusual. 



Casual or accidental records are, roughly, of two 

 kinds: first, birds recorded just beyond the margins 

 of their normal ranges, and second, birds from dis- 

 tant areas whose occurrence is wholly fortuitous. It 



