While on Cayo Island, in the Gulf of Mexico, on the 10th of April 1837, I observed large flocks of the Blue and Green Herons, _Ardea cœrulea_ and _A. virescens_, arriving from the westward about the middle of the day. They flew at a considerable height, and came down like so many hawks, to alight on the low bushes growing around the sequestered ponds; and this without any other noise than the rustling of their wings as they glided through the air towards the spot on which they at once alighted. There they remained until sunset, when they all flew off, so that none were seen there next day. This shews that although these species migrate both by day and night, they are quite diurnal during the period of their residence in any section of the country which they may have chosen for a season. It is more than probable that it has been from want of personal knowledge of the habits of these birds, that authors have asserted that all Herons are nocturnally inclined. This certainly is by no means the case, although they find it advantageous to travel by night during their migrations, which is a remarkable circumstance as opposed to their ordinary habits. In the instance above mentioned, I found the birds remarkably gentle, which was probably owing to fatigue. The Blue Heron breeds earlier or later according to the temperature of the district to which it resorts for that purpose, and therefore earlier in Florida, where, however, considerable numbers remain, during the whole year than in other parts of the United States. Thus I have found them in the southern parts of that country, sitting on their eggs, on the 1st of March, fully a month earlier than in the vicinity of Bayou Sara, on the Mississippi, where they are as much in advance of those which betake themselves, in very small numbers indeed, to our Middle Districts, in which they rarely begin to breed before the fifteenth of May. The situations which they choose for their nests are exceedingly varied. I have found them sitting on their eggs on the Florida Keys, and on the islands in the Bay of Galveston, in Texas, in nests placed amidst and upon the most tangled cactuses, so abundant on those curious isles, on the latter of which the climbing Rattlesnake often gorges itself with the eggs of this and other species of Heron, as well as with their unfledged young. In the Lower parts of Louisiana, it breeds on low bushes of the water-willow, as it also does in South Carolina; whereas, on the islands on the coast of New Jersey, and even on the mainland of that State, it places its nest on the branches of the cedar and other suitable trees. Wherever you find its breeding place, you may expect to see other birds in company with it, for like all other species, excepting perhaps the Louisiana Heron, it rarely objects to admit into its society the Night Heron, the Yellow-crowned Heron, or the White Egret.