Moose, like many ungulates, will sniff a female’s urine to see if she’s close to being receptive. They will then push the odor back into the nostril’s in what’s called a flehmen response. Many animals do this but male ungulates can often be seen doing it during the breeding season. The female moose was to my left and while she allowed the bull to stay close, she wasn’t quite ready to breed. He will stay close by until she is ready and chase off any challengers.