It is early June and this female grizzly is not in the water to cool off, actually the male should be in the water to cool off. Mating occurs from May through July with a peak in mid-June. Female grizzlies begin bearing young at 3 to 8 years of age, and litter size varies from one to four cubs, with an average litter of two. Grizzly bears have a promiscuous mating system: cubs from the same litter can have different fathers. The different fathers can be very obvious when the siblings have dramatically different colours or colour patterns. This male persisted and the female was in the water for more than two hours.