BRANCH CtfORDATA; CLASS AYES: THE BIRDS 361 



lie severer North at the beginning of winter and going 

 >ack with the coming of spring; these are winter resi- 

 ients. Some are to be found in the locality only in spring 

 ind autumn as they are migrating north and south 

 >etween their tropical winter quarters and their northern 

 lummer or breeding home; these are migrants. And 

 mally an occasional representative of certain bird species 

 vhose normal habitat does not include the given locality 

 it all will appear now and then blown aside from its 

 egular path of migration or otherwise astray; these are 

 visitants. As to the relative importance, numerically, 

 >f these various categories among the birds which may be 

 bund in a certain region and thus form its bird-fauna we 

 nay illustrate by reference to a definite region. Of the 

 551 species of birds which have been found in the State 

 >f Kansas (a region without distinct natural boundaries 

 ind fairly representative of any Mississippi valley region 

 )f similar extent), 51 are all-year residents; 125 are 

 ;ummer residents; 36 are winter residents; 104 are 

 nigrants, and 35 are rare visitants. 



It must also be kept in mind in using bird-keys and 

 lescriptions to determine species that the descriptions and 

 :eys refer to adult birds, and in ordinary plumage. 

 \mong numerous birds the young of the year, old enough 

 o fly and as large as the adults, still differ considerably 

 n plumage from the latter; males differ from females, 

 nd finally both males and females may change their 

 dumage (hence color and markings) with the season, 

 [he seasonal changes of plumage accomplished by molt- 

 ng may be marked or hardly noticeable. "All birds 

 ;et new suits at least once a year, changing in the fall. 

 ome change in the spring also, either partially or wholly, 

 , T hile others have as many as three changes perhaps, to 

 slight extent, a few more. ... It is claimed by some 

 bat now all new colors are acquired by molt, and by 



