The Warblers are migratory birds, the majority of them passing rapidly across the United States in spring on the way to their northern nesting grounds, and in autumn to their winter residence within the tropics. When the apple trees bloom they revel among the flowers, vieing in activity and numbers with the bees; "now probing the recesses of a blossom for an insect, then darting to another, where, poised daintily upon a slender twig, or suspended from it, they explore hastily but carefully for another morsel. Every movement is the personification of nervous activity, as if the time for their journey was short; as, indeed, appears to be the case, for two or three days at most suffice some species in a single locality." We recently saw a letter from a gentleman living at Lake Geneva, in which he referred with enthusiasm to BIRDS, because it had enabled him to identify a bird which he had often seen in the apple trees among the blossoms, particularly the present season, with which he was unacquainted by name. It was the Orchard Oriole, and he was glad to have a directory of nature which would enable him to add to his knowledge and correct errors of observation. The idea is a capitol one, and the beautiful Kentucky Warbler, unknown to many who see it often, may be recognized in the same way by residents of southern Indiana and Illinois, Kansas, some localities in Ohio, particularly in the southwestern portion, in parts of New York and New Jersey, in the District of Columbia, and in North Carolina. It has not heretofore been possible, even with the best painted specimens of birds in the hand, to satisfactorily identify the pretty creatures, but with BIRDS as a companion, which may readily be consulted, the student cannot be led into error. THE RED BREASTED MERGANSER. Why this duck should be called red-breasted is not at first apparent, as at a distance the color can not be distinguished, but seen near, the reason is plain. It is a common bird in the United States in winter, where it is found in suitable localities in the months of May and June. It is also a resident of the far north, breeding abundantly in Newfoundland, Labrador, Greenland, and Iceland. It is liberally supplied with names, as Red-Breasted Goosander or Sheldrake, Garbill, Sea Robin, etc. There is a difference in opinion as to the nesting habits of the Red-Breast, some authorities claiming that, like the Wood Duck, the nest is placed in the cavity of a tree, others that it is usually found on the ground among brushwood, surrounded with tall grasses and at a short distance from water. Davie says that most generally it is concealed by a projecting rock or other object, the nest being made of leaves and mosses, lined with feathers and down, which are plucked from the breast of the bird. The observers are all probably correct, the bird adapting itself to the situation.