Common warthogs are seasonal breeders. Rutting begins in the late rainy or early dry season and birthing begins near the start of the following rainy season. The mating system is described as "overlap promiscuity"; the males have ranges overlapping several female ranges, and the daily behavior of the female is unpredictable. Boars employ two mating strategies during the rut. With the "staying tactic", a boar will stay and defend certain females or a resource valuable to them. In the "roaming tactic", boars seek out estrous sows and compete for them. Boars will wait for sows to emerge outside their burrows. A dominant boar will displace any other boar that also tries to court his female. When a sow leaves her den, the boar will try to demonstrate his dominance and then follow her before copulation. For the "staying tactic", monogamy, female-defense polygyny, or resource-defense polygyny is promoted, while the "roaming tactic" promotes scramble-competition polygyny.