Note the black tips on the primaries, below the rump, of the little blue.

One theory has it that the white plumage of the immature, all-white, little blue heron allows it to be accepted among the great egrets, while the adult, mostly-blue, little blue herons are harassed & driven off. I haven't seen many adults, only 4 individuals in 10 years on Douglas Lake; they were either solitary or among juveniles. On the other hand, I've seen as many as 40 juveniles at one time there; great egrets are always numerous, in the hundreds, by late summer.