A. C. Bent, 1937, _U. S. Nat. Mus. Bull._ 167, p. 151 (red-tailed
hawk), p. 296 (golden eagle). M. R. Lieff and N. P. Jordan, 1950,
_British Birds_, Vol. 43, p. 56 (carrion crow). E. H. Forbush,
1929, _Birds of Mass., etc._, Vol. 3, p. 141 (purple martin). A. L.
Rand, 1936, _Bull. Amer. Mus. Nat. Hist._, Vol. 72, pp. 487, 490
(weaverbird).