UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 6, No. 13, pp. 285-312 December 28, 1910 



SIGNIFICANCE OF WHITE MARKINGS 



IN 



BIRDS OF THE ORDER PASSERIFORMES. 



BY 



HENRY CHESTER TRACY. 



CONTENTS. 



PAGE 



Introduction 285 



Intrinsic Eactors in the Evolution of Color 280 



White Markings as Visual Clues 289 



The Problem Discussed for Birds of the Open 295 



The Problem Discussed for Arboreal Species 297 



Special Study of the Mniotiltidae 305 



Sexual Selection as Affecting White Patterns 308 



Directive Markings Outside the Order Passeriformes 309 



Conclusion 309 



INTRODUCTION. 



The present investigation was undertaken fur the purpose 

 of testing the validity of one of the earliest recognized categories 

 (if coloration, that of "Directive Markings," in a single order 

 of birds. The term directive is used in the sense given it by Todd 

 (1888) and not that of later writers (Marshall, 1902), who have 

 used the word as expressing a different function of white 

 markings in butterflies' wings — protective through drawing the 

 enemy 's attack away from vital parts. As here used it resembles 

 the term recognition markings, and might be regarded as a 



* The present paper is the result of work carried on in the Department 

 of Zoology of the University of California as partial fulfillment of the 

 requirements for the master's degree, under the direction of Professor 

 Charles A. Kofoid, to whom the writer is indebted for advice and 

 criticism. He is also under many obligations to Mr. Joseph Grinnell,. 

 Director of the Museum of Vertebrate Zoology, for much information 

 placed at his dsposal. The author also had access to the large 

 collections in the Museum, and was allowed free use of these and of 

 such data on file there as proved pertinent to the problem in hand. 



