The lifespan of most cervid ranges from 11 to 12 years, however, many are killed before their fifth birthday due to various causes including hunting, predation, or motor vehicle collisions. In most species, males have shorter lifespans than females and this is likely a result of intrasexual competition for mates and the solitary nature of most sexually dimorphic males, resulting in increased risk of predation. However, recent studies show that sex-biased mortality rates are tightly linked to local environmental conditions. Captive deer tend to outlive their wild counterparts as they are subjected to little or no predation and have access to an abundant supply of food. The lifespan of cervids decreases as the number of deer exceeds the local environments carrying capacity. In this case, young and old cervids tend to suffer from starvation, as stronger, middle-aged deer outcompete them for forage.