Is it true? Did it really happen? The implications and correlations are my own, and some of the accounts on the previous pages are based on my experiences. But many of the facts come from the writings of others. Where the incidents are well known no documentation is given. But when the behavior described is little known or only recently discovered I've given a reference so that the source can be consulted. These are arranged under the appropriate chapter headings. BIRDS USING TOOLS Edna Fisher, _Jour. Mammalogy_, Vol. 20, p. 21 (sea otter). P. A. Gilbert, 1939, _Emu_, Vol. 39, pp. 18-22 (satin bower bird). D. Lack, 1947, _Darwin's Finches_, p. 59 (woodpecker finch). D. Morris, 1954, _British Birds_, Vol. 47, p. 33 (song thrush). A. C. Bent, 1921, _U. S. Natl. Mus. Bull._ 113, p. 111 (gull and crow). BIRDS AS BRIGANDS A. L. Rand, 1954, _Fieldiana-Zoology_ (Chicago), Vol. 36, p. 35 (eagle, skua, frigate bird). BIRDS BATHING F. N. Bassett, 1922, _Condor_, Vol. 24, p. 63 (hummingbirds). A. C. Bent, 1937, _U. S. Natl. Mus. Bull._, 167, p. 370 (osprey). HOW BIRDS ANOINT THEIR FEATHERS W. L. McAtee, 1938, _Auk_, Vol. 55, p. 98 (review). TRAVELING BIRDS' NESTS H. S. Swarth, 1935, _Condor_, Vol. 37, p. 84 (barn swallows). M. A. Common, 1942, _Auk_, Vol. 59, p. 43 (tree swallow). D. L. Serventy and H. M. Whittell, 1948, _Birds of Western Australia_, p. 243 (welcome swallow). MALADAPTATION IN BIRDS J. Grinnell, 1926, _Condor_, Vol. 28, p. 97 (robin). W. H. Bergtold, 1930, _Auk_, Vol. 47, p. 571 (robin). H. W. Henshaw, 1921, _Condor_, Vol. 23, p. 109 (California woodpecker). D. Bannerman, 1933, _Birds Tropical West Africa_, Vol. 3, p. 415 (thick-billed honey-guide). FEATHERED BABY SITTERS AND CO-OP NURSERY NESTS D. Davis, 1940, _Auk_, Vol. 57, p. 179 (ani). A. C. Bent, 1925, _U. S. Natl. Mus. Bull._, 130, p. 85 (eider duck). R. C. Murphy, 1936, _Oceanic Birds of South America_, Vol. 1, p. 398 (penguins). BIRDS' NESTS AND THEIR SOUP Gibson-Hill, 1948, _Malay. Nat. Jour._, Vol. 3, p. 190; F. H. Giles, 1935, _Jour. Siam Soc. Nat. Hist. Suppl._, Vol. 10, p. 137; and Jabouille, 1931, _L'Oiseau et Rev. Franc. d'Ornith._, Vol. 1, n.s., p. 219 (swiftlets). WALLED WIVES OF HORNBILLS R. E. Moreau, 1937, _Proc. Zool. Soc._ London, 1937, p. 331 (hornbills). BURIED EGGS AND YOUNG A. Newton, 1893, _Dictionary of Birds_, p. 733; and D. Bannerman, 1931, _Birds Trop. West Africa_, Vol. II, p. 205 (crocodile bird). Deusing, 1939, _Auk_, Vol. 56, p. 367 (grebe). Bent, 1925, _U. S. Natl. Mus. Bull._, 130, p. 98 (eider duck). THE SNOWY OWL AS A TRADE INDEX A. Gavin, 1947, _Wilson Bull._, Vol. 59, p. 202 (snowy owl). MONKEY BIRDS A. L. Rand, 1954, _Fieldiana-Zoology_ (Chicago), Vol. 36, p. 23 (various "monkey-birds"). BIRD-MADE INCUBATORS