When conditions are harsh in the dry season, impalas come together in mixed herds, which may number in the hundreds, to search for food. During the more plentiful wet season, males and females separate into different groups, with males competing for territories. Successful males mark their territories with urine and feces and then lure females into them with tongue-flashing displays. This signal has the effect of making the females group together as they pass through the displaying males. Non-resident males run away or flash their own tongues in defiance.