WILD LIFE OF ORCHARD AND FIELD 



But his dress is one of the least of the flicker's 

 diversities from his family type. This indepen- 

 dent cousin does not at all mind sitting crosswise 

 upon a branch, like a pigeon or any other percher, 

 whereas good form in the Picus family requires 

 its members to cling upright, with equally distend- 

 ed toes and the tail pressed in against the bark as 

 a support. A nicker also possesses this climbing- 

 irons kind of a tail, and spends a fair share of his 

 time in scrambling up and down tree-trunks and 

 fence-posts in search of the worms, wood-lice, and 



a problem of no small importance. It is a common thing 

 in birds to find the males and females differing decidedly 

 in color, and the young differing from adult specimens or 

 the same birds altering with change of season; but apart 

 from this there is a condition called dichromatism (sometimes 

 it seems to be even trichromatism), which is quite another 

 thing, and as yet not well explained. In dichromatism, 

 one species presents two different styles of permanent and 

 normal colors or styles of coloration. Examples of these 

 are found in certain parrots, which may be either red or green, 

 in some American hawks and sea-birds where both light and 

 dark colored individuals regularly occur, and in many owls^ 

 most commonly the familiar little screech-owl (Megascops 

 asio), where gray and reddish ones will grow up in the same 

 nest. Thus many birds, formerly regarded as separate, 

 have been shown to belong to one and the same species 

 whose members are sometimes in one dress and sometimes 

 in another equally normal. In the light of this fact Dr. 



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