27 o Recent Literature. LApril 



The climatic and physiographic conditions are said to be quite uniform 

 throughout the area under consideration, and, with the exception of the 

 grouse, "the avian fauna is everywhere much alike." In the case of the 

 mammals, however, "it is interesting to note that with one or two possible 

 exceptions there is no species of mammal that ranges unchanged through- 

 out the whole of the region." — J. A. A. 



Tracy's ' Significance of White Markings in Birds of the Order 

 Passeriformes.' — Thesubject 1 is considered under the following captions: 

 Intrinsic factors in the evolution of color; white markings as visual clues; 

 the problem discussed for birds in the open; the problem discussed for 

 arboreal species; special study of the Mniotiltidse; sexual selection as 

 affecting white patterns; directive markings outside the order Passeri- 

 formes; conclusions. The author has here assembled an interesting array 

 of facts, and has discussed them in a liberal spirit. The Passeriform birds 

 of North America are listed in groups with regard to whether they are 

 birds of the open-ground or are arboreal, and are further subdivided with 

 regard to their having or not having concealed white, or white wing and tail 

 markings, etc. In birds of the open, nearly all those with white markings 

 are "to be classed as flocking birds," while those without white marking 

 do not flock, with a few exceptions, for which special explanations are 

 offered . 



"Coloration in birds," says the author, "whatever its cause or the 

 mechanism of its production, is conceded to be adaptive; it responds to 

 their needs, forms a part of their life adjustments. Concealment from 

 its enemies is not the only need in a bird's life, not the only adjustment 

 that affects color-patterns. The bird also needs to be made known to 

 other individuals of its kind, and to other species associated with it; arid 

 this need has certainly been met. . . .The number and variety of perils 

 that daily surround our smaller land-birds, and the extent to which these 

 may be diminished by the birds' keeping in touch with one another, point- 

 to the need of something more than concealing coloration, and admit of 

 special adaptations that shall act in harmony with it and yet serve to 

 reveal the bird to its kind. . . . 



"Starting out with a presumption in favor of some form of revealing 

 clues among the higher land-birds, and eliminating a terminology [banner- 

 marks, etc.] which has been misleading, it remains for us to determine, if 

 possible, what these clues are, and whether color features form a part of 

 them; if so, how this harmonizes with the function of the same or similar 

 color features as concealing .... But general coloration is seen to be nor- 

 mally protective, for birds that need protection ; and as for special patterns, 

 even a satisfactory demonstration of their 'obliterative' effect does not 



1 Significance of White Markings in Birds of the Order Passeriformes. By Henry 

 Chester Tracy. University of California Publ., Zool., VI, No. 13, pp. 285-312. 

 Dec. 28, 1910. 



