Moose make grunting sounds most of the year, and during breeding season cows make longer calls in a variety of lengths to attract bulls. Bulls make aggressive grunting noises to challenge other bulls during breeding season.
Cow moose make broadcast calls to attract bulls from long distances. The cow moves her head around to create high and low pitched sounds, and makes the call for eight to ten seconds.
Cows make the in-estrus call when the bull is moving towards her, but stops. This call has a lower volume than the broadcast call and lasts for three to four seconds. The in-estrus whine has an "err" or humming sound and lasts two to three seconds. Cows use this when the bull is close to her but does not close the distance between them.