Mothers with Babies (or sometimes dads): Bighorn Sheep

Prior to the mating season or rut, the rams attempt to establish a dominance hierarchy that determines access to ewes for mating. It is during the pre-rut period that most of the characteristic horn clashing occurs between rams, although this behavior may occur to a limited extent throughout the year. Ram's horns can frequently exhibit damage from repeated clashes.  Females exhibit a stable, non-linear hierarchy that correlates with age. Females may fight for high social status when they are integrated into the hierarchy at 1–2 years of age. 

Rocky Mountain Bighorn rams employ at least three different courting strategies. The most common and successful is where a ram follows and defends an estrous ewe. Tending takes a lot of strength and dominance and thus ewes are more receptive to tending males, feeling that they are the most fit. Another tactic is coursing which is when rams fight tending rams for temporary access to defended ewes.  Ewes tend to avoid coursing males so the strategy is not effective. Rams will also employ a blocking strategy. They will prevent an ewe from accessing tending areas before she even goes into estrous.

Bighorn ewes exhibit a six-month gestation. In temperate climates, the peak of the rut occurs in November with one, or rarely two, lambs being born in May. Most births occur in the first two weeks of the lambing period. Pregnant ewes of the Rocky Mountains migrate to alpine areas in spring, presumably to give birth in areas safer from predation but are away from areas with good quality forage.  Lambs born earlier in the season enjoy greater survival than lambs born later. Ewes that give birth late in the season are at an earlier stage of lactation when forage quality declines and may not produce sufficient milk to ensure lamb survival. Newborn lambs weigh from 8 to 10 pounds (3.6 to 4.5 kg) and can walk within hours. The lambs are then weaned when they reach 4–6 months. The lifespan of rams is typically 9–12 years, with 10–14 years for ewes.

Rocky Mountain Bighorn Sheep: Ewe nursing Kid