A soft, flat, tonal rumble of medium duration (~2.5-4.5 seconds) and low pitch, given by adult or juvenile females in the context of caring for an infant or young calf. There are two broad behavioral contexts in which females call in this manner to a calf with whom they are in close proximity. One is when they greet, touch, suckle or generally "coo over" a calf in the absence of an expression of distress by the calf. Such calling is directed toward infants, rather than older calves, and is especially frequent when there is a newborn in the family. Juvenile females may also call in this manner when touching infants and when they encourage infants to Comfort-Suckle from them. Such touching induces calves to respond with a rumble (see As-Touched-Rumble).
Little E is 5 days old and is Suckling. His mother, Mama Little E has put her foreleg forward to adopting a Suckle-Stance. As he is Suckling she reaches her trunk and touches under his mouth (Trunk-to-Mouth) and gives a Coo-Rumble. Little E is getting the hang of Suckling, but must lift a foreleg to reach her nipple. (Maasai Mara, Kenya)