OXPECKERS
D. Bannerman, 1948, Birds of Tropical West Africa, Vol. 6, p. 105 (oxpecker).
WINGS IN FEEDING
J. Delacour, 1946, Auk, Vol. 63, p. 441 (black heron).
CONDITIONING IN BIRDS
A. L. Rand, 1942, Bull. Amer. Mus. Nat. Hist., Vol. 79, p. 517 (shrikes).
POISONOUS BIRDS
E. H. Forbush, 1927, Birds of Mass., etc., Vol. 2, p. 34 (ruffed grouse). D. L. Serventy and H. M. Whittell, 1948, Birds of Western Australia, pp. 73, 74 (Australian pigeons). R. Meinertzhagen, 1912, Ibis, p. 96 (Mauritius pigeon).
BIRDS WASHING FOOD
F. G. Evenden, 1943, Condor, 45, p. 120 (dipper). For divers records of washing food see British Birds for 1946, 6 and 8.