76 



The Canadian Field-Naturalist. 



Vol. XXXV. 



8WARTH ON THE FOX SPARROW. 

 By p. a. Taverner. 



This monograph on the Fox Spcirrows is 

 an excellent example of the species-splitter 

 at his best, and worst. That sixteen sub- 

 species are recognized is testimony to the 

 fineness of the splitting, but the use made 

 of these fragments goes a long way to 

 justify the process. Too often systematists 

 have assumed, .when they have divided their 

 species into as many fractional parts as 

 possible, that their responsibility was end- 

 ed, whereas they have only just laid out 

 their tools for serious scientific effort. Mr. 

 Swarth realizes that splitting is a means to 

 an end and not an end in itself, and has 

 developed his subject with a grasp and ap- 

 preciation of the problems involved that 

 is all too rare in revisions of this kind. 



The first 29 pa^es are taken up by an 

 introduction and chapters on Materials 

 and Methods of Treatment, Histoiy, Varia- 

 tion in Passerella iliaca and Distribution 

 and Migration that ^re models of their 

 kinds. The remainder is composed of 

 systematic treatment, description and dis- 

 cussion of the races considered, a list of all 

 the material examined and a beautifully 

 drawn and colored plate from the brush of 

 our countrj^man Major Allan Brooks illus- 

 trating the extremes of two subspecific 

 groups. 



The species is remarkably homogeneous 

 over most of the continent but breaks up 

 into many races within and west of the 

 Rocky Mountains. These races are dis- 

 cus.sed, their relationships pointed out. 

 they are traced from their summer to their 

 winter, habitat, and many interesting prob- 

 lems regarding them are suggested. 



An interesting conclusion is derived 

 from the movements and distribution of the 

 l^ritish Columbia and Alaska coastal forms. 

 Tliose that summer farthest north winter 

 the farthest south. The more southern 

 breeders winter more northerly, and so on 

 [irogressively to the Vancouver Island 

 vicinity bii-(ls which are practically station- 

 ary throughout the year. 



Another important point brought out is 

 tliat the birds In-eediiig in the most humid 

 climates are not the darkest or the largest 

 of the species. Unalosrhnisin, summering 

 in the extremelv moist Ahiskan Peninsula, 



does not reach the extreme development of 

 size or depth of color that is attained by 

 fidiginosa, resident on the comparativeh' 

 dry Vancouver Island region. This per- 

 plexing fact that would otherwise serious- 

 ly shake one of our most cherished ecolo- 

 gical principles is explained by the fact 

 that tjie northern race spends its winter 

 in arid southern California, and probably 

 experiences a much lower annual average 

 moisture than does the darker and larger 

 race. It is thus brought forcibly to our 

 notice that, in studying the relationship 

 between the bird and its environment, 

 winter ranges and probably migrational 

 routes should also be taken into considera- 

 tion. 



Some distributional anomalies are point- 

 ed put. Some forms range widely over 

 varied and more or less discontinuous con- 

 ditions unmodified, whilst very slight bar- 

 riers have induced specialization in others. 

 Kadiak Island, but slightly isolated from 

 adjoining territory, has its definable sub- 

 species, insularis, yet the Queen Charlot- 

 tes, situated far out to sea and noted for 

 their peculiar forms, have developed no 

 specialization in this species. 



Mr. Swarth divides the Fox Sparrow, 

 Passerella iliaca, into sixteen subspecies 

 falling into three groups which for con- 

 venience he calls after their most char- 

 acteristic coniponoiit members. Thus he 

 gives us : — 



I. — The Iliaca group. 



1. P. i. iliaca 



2. P. i. altaiuif/diis 



11. — The Hnalaschensis grou]). 



1. P. i. unalaschcnsis 4. P. i: annectena 



2. P. i. insularis 5. P. i. townsendi 

 ;5. P. i. sinuosa 6. J\ /. fnligiiwsa 



III.- -Tlic Schistacea group. 



1. /-'. /. schistacea 5. P. i. conascens 



2. /'. /. fulva (). /'. /. monolensis 

 '■>. P I. niegarhijHcliKs 7. /'. /. mariposac 

 '■>. P. i. hrevicavdd S. /'. /. stcphensi 



Of these we have nine in Canada either 

 as l)reeders or migrants, including all the 

 first two groups and the first of the tliird. 



