National Geographic : 1951 Aug
Dinner Is Served! Few Other Birds Feed Their Young While Hovering, Like Hummers Wings beating rapidly, the Broad-tail thrusts her long, sharp bill deep into the youngster's gullet (page 256). Feeding by regurgitation, she supplies a diet of nectar, spiders, and insects. In about three weeks, the expanding bodies of the young have pressed the little nest out of all shape. They are now as large as the parents and wear a full covering of feathers. For a time they exercise their wings at the nest, then take off in flight. Though they still are fed by the mother for a few days, they soon have mastered the art of hummingbird flight-up, down, forward, sideways, and even backwards. Backward Flight Is No Illusion In 1867 the Duke of Argyll, in his The Reign of Law, stated that no bird could fly backwards. He conceded that the humming bird might appear to do so as it left a flower, but held that this was an optical illusion; that the bird really fell away, turned, and flew ahead. Undoubtedly the noble author never watched a hummer fly, because it is easy to see that the bird does fly backwards. To demonstrate the performance photo graphically, we contrived a switch to set off three flashes in extremely rapid succession, so that the hummingbird would appear in three positions on the same film. The first flash showed the bird's bill leaving the feeding bottle; the second and third proved actual backward flight (page 247). This photograph shows graphically another hummingbird feature, the long, protruding tongue, the organ that distinguishes the hum mingbird sharply from other bird groups. A sort of double-barreled tube, split and fringed at the tip, the tongue can be extended beyond the bill tip nearly as far as the bill's own length. This remarkable implement acts as a sucking tube to extract nectar from flowers and also as a probe or sticky brush for collect ing small insects found there. Since our pictures were made at varying distances from the subject, it was not possible to make the reproductions to scale. To give some idea of relative size, here are significant dimensions of the Broad-tail: length from tip of bill to tip of tail, 42 inches; length of bill, 34 inch; over-all diameter of nest, 15/l inches. In mid-July we returned to the Evans Ranch in Colorado to look for the Rufous Humming bird (Selasphorus rufus). During a lull in the rain, Van Riper and Niedrach went to the meadow behind camp to look for birds. Sud denly Van Riper shouted to his companion, "Come quick, the Rufous are here!" Three adult males, with fiery throats and copper colored backs, darted about, sipping nectar from the common mountain flower, the pent stemon.