318 The Naturalist in La Plata. 



from all competition with otlier birds as the solitary 

 savage is removed from the struggle of life affect- 

 ing and modifying men in crowded communities. 

 The lower kind of competition affecting humming- 

 birds, that with insects and, within the family, of 

 species with species, has probably only served to 

 intensify their unique characteristics, and, perhaps, 

 to lower their intelligence. 



Not only are they removed from that indirect 

 struggle for existence which acts so powerfully on 

 other families, but they are also, by their habits 

 and the unequalled velocity of their flight, placed 

 out of reach of that direct war waged on all other 

 small birds by the rapacious kinds — birds, mammals, 

 and reptiles. One result of this immunity is that 

 humming-birds are excessively numerous, albeit such 

 slow breeders ; for, as we have seen, they only lay 

 two eggs, and not only so, but the second egg is 

 often dropped so long after incubation has begun 

 in the first that only one is really hatched. Yet 

 Belt expressed the opinion that in Nicaragua, where 

 he observed humming-birds, they out-numbered all 

 the other birds together. Considering how abun- 

 dant birds of all kinds are in that district, and that 

 most of them have a protective colouring and lay 

 several eggs, it would be impossible to accept such 

 a statement unless we believed that humming-birds 

 have, practically, no enemies. 



Another result of their immunity from persecu- 

 tion is the splendid colouring and strange and 

 beautiful feather ornaments distinguishing them 

 above all other birds ; and excessive variation in 

 this direction is due, it seems to me, to the very 



