Cathartes macrourus up to second bird then opened wings & went right into calling. It then gave beginning of cop. call, other bird sat & it deserted & sat. This elevation of head stummation to challenge is now 4:32 Saw pair feeding at distant nest. Heard begging call. Introducing note a will with in quality. (i.e. two which seem 'im'. you can't you fool but the bird can. & ii in iii notes only 3 or 4 r on same same pitch a little lower then first note & rest in descending series. This was landed member of pair which then walked back to nest & sat, mate flew off. (Recent Group of 4 which includes F.) 4:40 Water now flowing past mound rest did yesterday afternoon about this time. This channel was dry when dammed Dec 9th. 4:45 p.362 walked 10 ft N. One chased a bird by spreading wings, fluffing feathers & flinging. Grabbed bird which squealed, struggled loose & flew. Other bird in upright walked over to another spread bill soundly & other bird flew. Head not moved bill simply parted. Finally chased third bird, both, and pronounced. This last on film 16 mm 4:52 Mates of 204 + 230 both return from Spa.