The California Jays 



fore, the situation is not one for alarm. The jays have been here for a long 

 time, longer than we have even — say for a million years longer. Per- 

 haps the average adjustment of Nature's forces has been pretty well 

 attended to. Certainly we shall not set about the destruction of all 

 jays. That would assure a violent reaction of some sort, and might 

 entail infinite hardship. But I agree with Beal 1 that a reduction of, 

 say, one-half in the number of the now ubiquitous California Jay might 

 be a good thing. 



If ever an oologist had a clear commission for "intensive study" of 

 birds' eggs, it exists in the case of the California Jay. He at least cannot 

 complain when his nest is robbed. Accordingly, we rejoice at the presence 

 in our State of some fine series of California Jays' eggs. Moreover, no 

 fitter subject for intensive study could be chosen, for the eggs of the 

 California Jay are abundant, highly variable, and of undeniable beauty. 

 It is the variability of these eggs which interests us most; for in the 

 consideration of almost any series two types present themselves, the 

 "red" and the green. This dichromatism of the egg is a prominent 

 factor in tropical bird life, notably that of India, where it occasionally 

 becomes trichromatism; but Aphelocoma calif ornica furnishes about the 

 only instance, certainly the clearest instance (save for the circumpolar 

 Murre), in America. 



The red type is much the rarer. In this the ground color varies from 

 clear grayish white to the normal green of the prevailing type; while the 

 markings — fine dots or spots or, rarely, confluent blotches — are of a warm 

 sepia, bister, verona brown, or Rood"s brown. The ground color of the 

 green type varies from pale sulphate green to lichen green, and the 

 markings from deep olive to Lincoln green. In the Museum of Compara- 

 tive Oology we have a set kindly furnished by Mr. H. W. Carriger, whose 

 markings are reduced to the palest subdued freckling of pea-green. In 

 another set, of the red type, fine Mars brown markings of absolute uni- 

 formity cover the egg; while the eggs of another set are covered as to their 

 larger ends with an olive-green cloud cap, which leaves the remainder of 

 the specimen almost free of markings. 



The precise significance of this high degree of variability is not 

 clear to our imperfect knowledge. It is one of those obscure Mendelian 

 characters whose genesis we cannot trace, but whose continuance along 

 definite lines of heredity we can confidently predict. We know now, for 

 example, that these jays breed true to their own type year after year; 

 that the owners of the coveted red type will present the enterprising 

 oologist with another set precisely similar, if their nest is found on a 



•Op. cit. p. 56. 



55 



