The Abert Towhee 



species concepts is one of 

 the most pernicious influ- 

 ences in science. We can- 

 not avoid it altogether, 

 but we can face it out and 

 persistently discredit it. 

 Thus it is that the mere 

 assignment of names 

 breaks up and artificially 

 spaces out certain groups 

 of bird species whose differ- 

 ences, though constant, 

 are almost infinitesimal; 

 and it contracts and ren- 

 ders inoperative the value- 

 distances which separate 

 certain other species whose 

 names, if we were consist- 

 ent, could not be printed 

 on the same page, or even 

 in the same book. 



As a practical illus- 

 tration of all this I would 

 cite the case of the genus 

 Pipilo. Regarding for 

 the present only those rep- 

 resentatives of the genus 

 which occur above the 

 Mexican border, and dropping for the moment sub-specific 

 terminations, we have five species to deal with : Pipilo 

 maculatus, P. erythrophthalmus, P. fuscus, P. aberti, and 

 P. crissalis. The mere enumeration of these species names gives each one dignity and 

 value, a place among its fellows. Whatever the facts may be, naming terms coordi- 

 nates them. It gives them equal value to our human apprehension. And though 

 we spend the rest of our lifetime specializing on the genus Pipilo, we shall never be 

 able to shake off this initial presumption that Pipilo aberti is as distinct, as different, 

 as important, as P. maculatus. Yet if we regard evolutionary distance, or what I 

 have called value distance (for evolution proceeds in different stocks at very 

 different rates), we shall find the three members of the Pipilo fuscus-aberti-crissalis 

 group, the Brown Towhees, as close together as three contiguous Earths; while the 

 members of the Pipilo maculatus group would figure as a constellation of Neptunes. In 

 other words, a printed list of the names of members of the genus Pipilo is as inexpressive 

 of the value distances which actually separate them, as would be a printed catalog of 

 the names of the planets to one who had never heard of the solar system. 



Taken in Riverside County 

 Photo by Donald R. Dickey 



NEST AND EGGS OF 

 ABERT TOWHEE 



399 



