Part 17

Reason in woodpeckers' hoarding, 62.

Red-head. See Woodpecker, red-headed.

Robins, 39.

Sap, not used as an insect-lure, 41. how its loss harms the tree, 44, 45.

Sapsucker, orange, 65. See, also, Woodpecker, red-bellied. red-breasted, 122. red-naped, 121. Williamson's, 122. yellow-bellied, 7, 15-17, 33-45, 59, 102, 103, 105, 106.

Skull of woodpecker figured, 101.

Sparrow, English or house, 21, 62, 65.

Spears, 12, 13.

Spruce, acorns stored in, 47, 49, 53.

Squirrels, thievishness of, 23, 53.

Subspecies defined, 114.

Swallow, eaves or cliff, 61, 64, 65.

Swallow, tree, 21.

Swift, chimney, 5, 20, 61, 87, 88.

Tail, shape, 89. number of rectrices, 95. experimental demonstration of shape a priori, 91. reason for shape, 98.

Tail-feathers studied, 94-97.

Taste in the woodpeckers, 38, 39.

Telegraph poles resorted to by woodpeckers, 7, 18, 48.

Thumb, of birds, 80.

Tin roofs resorted to by woodpeckers, 17, 55.

Titmouse, crested, 21.

Toes, numbering of, 79, 80.

Tongue, appearance of, 99. figured, 99. bones of, 13, 100-103.

Trogons, yoke-toed, 82.

Vanessa butterfly, 16.

Vegetable food of woodpeckers, 3, 31.

Vireos, 30.

Warblers, 30.