Alexander AGASSIZ - The naturalist in Nicaragua

clear and sparkling brook is reached, coming down to join its pure waters with the soiled river below. In the evening this was a favourite resort of many birds that came to drink at the pellucid stream, or catch insects playing above the water. Amongst the last was the beautiful blue, green, and white humming-bird (Florisuga mellivora, Linn.); the head and neck deep metallic-blue, bordered on the back by a pure white collar over the shoulders, followed by deep metallic-green; on the underside the blue neck is succeeded by green, the green from the centre of the breast to the end of the tail by pure white; the tail can be expanded to a half circle, and each feather widening towards the end makes the semicircle complete around the edge. When catching the ephemeridae that play above the water, the tail is not expanded: it is reserved for times of courtship. I have seen the female sitting quietly on a branch, and two males displaying their charms in front of her. One would shoot up like a rocket, then suddenly expanding the snow-white tail like an inverted parachute, slowly descend in front of her, turning round gradually to show off both back and front. The effect was heightened by the wings being invisible from a distance of a few yards, both from their great velocity of movement and from not having the metallic lustre of the rest of the body. The expanded white tail covered more space than all the rest of the bird, and was evidently the grand feature in the performance. Whilst one was descending, the other would shoot up and come slowly down, expanded. The entertainment ended in a fight between the two performers; but whether the more beautiful or the more pugnacious were the accepted suitor, I know not. Another fine humming-bird seen about this brook was the long-billed, fire-throated Heliomaster pallidiceps (Gould), generally engaged in probing long narrow-throated red flowers, forming, with their attractive nectar, complete traps for the small insects on which the humming-birds principally feed, the bird returning the favour by carrying the pollen of one flower to another. A third species, also seen at this brook, Petasophora delphinae, Less., is of a dull brown colour, with brilliant purple ear-feathers and metallic-green throat. Both it and Florisuga mellivora are short billed, generally catching flying insects, and do not frequent flowers so much as other humming-birds. I have seen the Petasophora fly into the centre of a dancing column of midges and rapidly darting first at one and then at another, secure half-a-dozen of the tiny flies before the column was broken up; then retire to a branch and wait until it was re-formed, when it made another sudden descent on them. A fourth species (Heliothrix barroti, Bourc.), brilliant green above, white below, with a shining purple crest, has also a short bill, and I never saw it about flowers, but always hovering underneath leaves and searching for the small soft-bodied spiders that are found there. Two of them that I examined had these spiders in their crops. I have no doubt many humming-birds suck the honey from flowers, as I have seen it exude from their bills when shot, but others do not frequent them. The principal food of all is small insects. I have examined scores of them, and never without finding insects in their crops. Their generally long bills have been spoken of by some naturalists as tubes into which they suck the honey by a piston-like movement of the tongue; but suction in the usual way would be just as effective; and I am satisfied that this is not the primary use of the tongue, nor of the mechanism which enables it to be exserted to a great length beyond the end of the bill. The tongue, for one-half of its length, is semi-horny and cleft in two, the two halves are laid flat against each other when at rest, but can be separated at the will of the bird and form a delicate pliable pair of forceps, most admirably adapted for picking out