Cathartes macrourus: Each time it gave way to a bird desiring the food it was picking at. It never was seen give a challenge display but in each instance reverted to chick behaviour & was displaced from the food. This is probably abnormal behavior such a bird could hardly defend a territory or mate normally. I wonder though. Nov. 27 P. L.: Down feathers were about site when one was sitting. It seemed pretty attached to the site & an egg may be forthcoming N.-1 egg. Down scattered among rocks about nest site. Next 1 with 2 eggs (second one new today) had down & at least one contour feather about nest. D- had food down about nest site also. 235 - 1 egg - " " " " " " 209 - Down feathers about site up slope from the cavern. 77 - Φ egg. Down present about site. Witnessed one attempted copulation on hillside, and one copulation on small, snow patch during round. Also I remark seeing a pair in copuli yesterday. This is getting rare now in the shivery as eggs laying seems about to end soon.