STABILITY OF EOOKEEY OUTLINES. 87 



Aside from the mass of downiight misinformation a good deal of harm has been 

 done by the often too sweeping generalizations based upon a few isolated facts and 

 caused by ignorance of the true relations of the latter as exceptions and not as rules. 



It must not for one moment be imagined that the lines are as tightly drawn in 

 nature as in many books and reports. It will probably be possible to cite more or 

 less isolated occurrences contrary to nearly every habit of the seals as generally 

 outlined. These exceptions are not frequent enough nor important enough to affect 

 the general result, and it may be confidently asserted that the investigations which 

 have of late been carried on by the American Bering Sea Commission of 1891 and 

 quite recently by the United States Pish Commission have brought out correctly the 

 main facts relating to the life-history of the seals. 



We have frequently seen, however, that the various exceptions alluded to have 

 been brought forward in the controversies relating to this theme as particularly 

 essential, thus obscuring the main questions, while on the other hand conditions have 

 been described and depicted as so uniform and stable that it has been easy for the 

 opposite side to controvert these assertions, thus throwing doubt upon the correctness 

 of the whole argument and the soundness of the conclusions. It may be useful, 

 therefore, to review a few of these questions. 



A protracted stay at the rookeries reveals two facts. The one which probably 

 first impresses the observer is the curious stability of the general outline of the 

 groups of breeding seals, especially if the comparisons be made at frequent intervals 

 during the earlier part of the season. The masses of seals assume certain definite 

 shapes which in many cases have no apparent relation to the nature of the ground 

 upon which they are lying. Thus, on the North Eeef Eookery on Bering Island, a 

 very peculiar feature of the distribution of the breeding seals this summer was a 

 narrow band of seals which extended obliquely across the northern end of the 

 "parade grounds," cutting off from the latter a small oval portion, visible in most of 

 the photographs (pis. 19, 21, 22) and also indicated in the map (pi. 8), and connecting 

 the masses of seals on the western side of the reef with those on the eastern side. 

 I have walked over the territory thus curiously occupied many a time, but I have 

 failed to find any difference in the ground which will account for this belt or answer 

 the question why the seals do not also occupy the bare oval island it surrounds. 



To appreciate this general stability of the outline it is necessary to have had an 

 opportunity to observe the rookery for some length of time. A person who had only 

 a few days at his disposal for examining the same rookery might, on the other hand, 

 be impressed by the fact that on two different days, or at different hours of the same 

 day, the outlines thus referred to present entirely different aspects, and if he offered 

 photographs in evidence of this fact he might seemingly prove the instability of these 

 lines. Thus the "baud" of seals on the North Eeef Eookery above alluded to did 

 occasionally entirely disappear, particularly during the warmer portion of bright, 

 sunny days, or after the rookery had been disturbed by a recent drive (see pi. 26). 



Nevertheless this "band" was a very characteristic feature of the seals on that 

 rookery. Single photographs are therefore of no particular value for comparison /rom 

 year to year unless they are talcen by a person familiar with the characteristic distribution 

 and the view is selected by him for that particular purpose. The main reliance must, 

 therefore, be placed upon the observer, and his statements must be received in 

 accordance with his known experience, accuracy, and intelligence. 



