1910] 



Tracy: Whit< Markings in Birds 



301 



Frixmi.udae 



Pyrrhula cassini 



Carpodacus purpurt us 



Carpodacus cassini 



Carpodat us mi a icanus frontalis, 



and other subsp. 

 < '.a podacus amplus 

 Lu.no curvirostra 



Am ii I Ins Unarm 



dcanthis hornt manni 

 Spinus pinus 

 Astragalinus lawri net i 

 Cardinalis cardinalis 

 Mi lospiza an lodia 

 Mi lospiza n< orgiana 

 Mdospi:a lincohii 

 Zonotrichia albicollis 

 Zonotrichia It ueophrys 

 Zonotrichia coronata 

 Zonotrichia qiicrnla 

 Passerella iliaca 

 Empidonax difficilis 

 Empidonax flaviventris 

 Empidonax trailli 

 Empidonax minimus 



Empidonax hammondi 

 Empidonax wrighti 

 Empidonax virt set ns 

 Empidonax grist us 

 Empidonax fulvifrons 

 Pyroct phalus rubint us 



can lis 



Camptostoma irribt rbt 



lln;l OINIDAE 



Progne chalybea 

 Proline Stlbis 



I' ognt cryptolt uca 

 Iridoproctu bicolor 

 Biparia riparia 



BOMBYCILLIDAE 



Bombycilla cedrorwm 



YlREONIDAE 



Virt osylva olivact u 



V in -os ill va philadt Iphica 



Vireosylva gilva 



I. nun in i> flu: i Irons 

 I a i a atricapillus 

 I'm a nri- 1 us 

 Virt o i i' inior 



The facts as to the distribution of white markings among 

 birds lit' the various local associations may be gathered from a 

 study of the first list. It also affords a basis for finding any 

 agreement of physical or temperamental characters among birds 

 so marked, or the occurrence of habits that may have a bearing on 

 their coloration. A similar purpose is served by the second list 

 — with this drawback: it includes a number of color features that 

 may be of a value similar to that of white patterns, and even 

 more revealing. Accordingly we need not be surprised it' we 

 find among species bearing such features, for example, nearly all 

 the crows and blackbirds, the habits and distribution that 

 are characteristic of white-marked birds. 



There is, moreover, a correspondence, especially among the 

 unmarked groups, that appears to be due primarily to intrinsic 

 influences producing family characters; like all color characters 

 these are too inconstant for the systematist to utilize. Still, in 

 some cases they suggest a persistence of some ancestral type 

 dominating extrinsic influences. Such a correspondence is seen 



