INDEX. 
Acquaintance with birds, 230. 
Aftershaft, 28. 
Air currents, in flight, 174. 
Air sacs, colored, 46, 140. 
Air spaces, not for buoyancy, sup- 
plementing lungs, 20; ia pelican 
forms, 140. 
Albatross, flight and wing, 172, 178. 
Allen, Grant, on origin of choice, 48. 
Altricial birds, without down usu- 
ally, 29; molt of wing quills of, 
38 ; affected by hatching heat, 100 ; 
traits of, 123-125; origin of a de- 
generation, 124; mostly tree build- 
ers, 127; outlined on diagram, 202. 
Altruism, 52; automatic, 53; invol- 
untary, 57. 
Ambiens muscle, 157, 193. 
Amphibians, differ from birds, how, 
3. 
Antelopes, signal marks on, 54; pe- 
culiar weapons of some, 60. 
Antics, as charming factors, 45 ; with 
display and choice, 48 ; chapter on, 
69; vigor, 69; on the wing, 71; 
older than wing, 77. 
Apteryx (Kiwi), with hairlike plu- 
mage, 34; smell of, 75 ; lays largest 
egg relatively, 126; feeding habits 
of, 137 ; kinship of, 138, 204 ; origin 
of beak of, 145, 150; roosting of, 
155. 
Aquatic birds, and downs, 27; feet 
of, 161 et seq.; outline on diagram, 
202 ; near precocial, 214 ; diagnosed 
213 et seq. 


Archeopteryx, lizardlike, feathers 
on legs and tail of, 5, 8; flight of, 
9; bones of wing free, 10 ; thumb 
of, alongside, 10 ; use of claws, 11; 
bipedal motion of, 15; quills par- 
tially flossy, 34; leg of, 167, 202, 
203. 
Arcties, origin of birds in, 117, 178, 
179. 
Argus pheasant, 58. 
Asia, some birds from, 187. 
Attention in bird study, 231. 
Audubon, notes on flicker and wood- 
pecker battles, 65. 
Auks, skin about bill of, 45; kinship 
and aquatic habits, 139, 207, 208. 
Backbone, origin of, 1; in water, 6; 
on skin, 30. 
Bare tracts, 22; and flight, 24; on 
aquatic birds, 27. 
Barrel of feather, 27 ; once flat, 33. 
Battle, indifference of female to, 45 ; 
by females, 50; in general, 59. 
Beak (bill), lengthened in charming 
season, 44; colored, 45; bent side- 
wise, 47 ; modified for food taking 
only, 60; of Apteryx flexible, 137 ; 
of snipes, ete., bent into a hook, 
138 ; fringed in ducks, 139 ; knife- 
like in a gull form, 140; sac be- 
neath in pelican group, 140 ; pierc- 
ing in waders and hooked in birds of 
prey, 141 ; of Apteryx, 150 ; affected 
by use and environment, 145, 146 ; 
of parrots hooked, file in roof of, 
21 201 
