Leaving the creek the next morning by starlight, I passed large flocks of geese and ducks, while Whooping-cranes (Grus Americanus) and Sand-hill cranes (Grus Canadensis), in little flocks, dotted the grassy prairies, or flew from one swamp to another, filling the air with their startling cries.  Both these species are found associated in flocks upon the cultivated prairie farms, where they pillage the grain and vegetable fields of the farmer.  Their habits are somewhat similar, though the whooping-crane is the most wary of the two.  The adult Whooping-cranes are white, the younger birds of a brownish color.  This species is larger than the Sand-hill Crane, the latter having a total length of from forty to forty-two inches.  The Sand-hill species may be distinguished from the Whooping-crane by its slate-blue color.  The cackling, whooping, and screaming voices of an assembled multitude of these birds cannot be described.  They can be heard for miles upon the open plains.  These birds are found in Florida and along the Gulf coast as well as over large areas of the northern states.  They feed upon soft roots, which they excavate from the swamps, and upon bugs and reptiles of all kinds.  It requires the most cautious stalking on the part of the hunter to get within gunshot of them, and when so approached the Whooping-crane is usually the first of the two species which takes to the wing.  The social customs of these birds are most entertaining to the observer who may lie hidden in the grass and watch them through a glass.  Their tall, angular figures, made up of so much wing, leg, neck, and bill, counterpoised by so little body, incline the spectator to look upon them as ornithological caricatures.  After balancing himself upon one foot for an hour, with the other drawn up close to his scanty robe of feathers, and his head poised in a most contemplative attitude, one of these queer birds will suddenly turn a somersault, and, returning to his previous posture, continue his cogitations as though nothing had interrupted his reflections.  With wings spread, they slowly winnow the air, rising or hopping from the ground a few feet at a time, then whirling in circles upon their toes, as though going through the mazes of a dance.  Their most popular diversion seems to be the game of leap-frog, and their long legs being specially adapted to this sport, they achieve a wonderful success.  One of the birds quietly assumes a squatting position upon the ground, when his sportive companions hop in turn over his expectant head.  They then pirouette, turn somersaults, and go through various exercises with the skill of gymnasts.  Their sportive proclivities seem to have no bounds; and being true humorists, they preserve through their gambols a ridiculously sedate appearance.  Popular accounts of the nidification of these birds are frequently untrue.  We are told that they build their cone-shaped nests of mud, sticks, and grass in shallow water, in colonies, and that