snarl with its mouth wide open, the eyes staring threateningly ahead and the ears folded backward. This may be accompanied by moans, hisses and growls, and hitting the ground with the forepaws. Cheetahs have rarely been observed scavenging kills; this may be due to vultures and spotted hyena adroitly capturing and consuming heavy carcasses within a short time. Reproduction and life cycle Cheetahs are induced ovulators and can breed throughout the year. Females can have their first litter at two to three years of age. Polyestrous, females have an oestrus ("heat") cycle is 12 days long on average, but it can vary from three days to a month. A female can conceive again after 17 to 20 months from giving birth, or even sooner if a whole litter is lost. Males can breed at less than two years of age in captivity, but this may be delayed in the wild until the male acquires a territory. A 2007 study showed that females who gave birth to more litters early in their life often died younger, indicating a trade-off between longevity and yearly reproductive success. Urine-marking in males can become more pronounced when a female in their vicinity comes into oestrus. Males, sometimes even those in coalitions, fight among one another to secure access to the female. Often one male will eventually win dominance over the others and mate with the female, though a female can mate with different males. Mating begins with the male approaching the female, who lies down on the ground; individuals often chirp, purr or yelp at this time. No courtship behaviour is observed; the male immediately secures hold of the female's nape, and copulation takes place. The pair then ignore each other, but meet and copulate a few more times three to five times a day for the next two to three days before finally parting ways. After a gestation of nearly three months, a litter of one to eight cubs is born (though those of three to four cubs are more common). Births take place at 20–25 minute intervals in a sheltered place such as thick vegetation. The eyes are shut at birth, and open in four to 11 days. Newborn cubs might spit a lot and make soft churring noises; they start walking by two weeks. Their nape, shoulders and back are thickly covered with long bluish grey hair, called a mantle, which gives