Cathartes melancphalus 36 Make 1960 No. 18 + Station drew head in & folded wings raised neck & went into "bill down" pose Turning head away from opponents at same time. They challenged & ended in bill down (neststone did not sure of role). Bird sat where it was. Other bird 10 feet away & believe associated with it didn't move. An incubating bird gave interesting challenge - began in head up bill down (then opened bill) gave challenge call & finally raised head & called. All done in smooth sequence while remaining sitting on nest. Wingpenea raised. 4:09 Rty-0 left nest + flew to Lty-0 on mound. A third bird had landed next to Lty-0. The bird flew a both Y-0s challenged, Left Y-0 sat stone, Rty-0. Stands there. 4:11 Lty-0 flies to nest & sits near it. Rty-0 still standing 4:13 Lty-0 gets up, walks 2 feet to nest + settles on it. Rty-0 standing on mound. 4:25 Rty-0 eating snow on side of mound. 4:32 Rty-0 gone. 4:45 Lty-0 landed 9 feet from nest Rty-0 began shelling the mate walked slowly over from 15 feet away sat in bowl 3-4 feet from