in mud holes to cool down. The white rhinoceros is thought to have changed the structure and ecology of the savanna's grasslands. Comparatively, based on studies of the African elephant, scientists believe the white rhino is a driving factor in its ecosystem. The destruction of the megaherbivore could have serious cascading effects on the ecosystem and harm other animals. White rhinos produce sounds which include a panting contact call, grunts and snorts during courtship, squeals of distress, and deep bellows or growls when threatened. Threat displays (in males mostly) include wiping its horn on the ground and a head-low posture with ears back, combined with snarl threats and shrieking if attacked. The vocalizations of the two species differ between each other, and the panting contact calls between individual white rhinos in each species can vary as well. The differences in these calls aid the white rhinos in identifying each other and communicating over long distances. The white rhinoceros is quick and agile and can run . White rhinos live in crashes or herds of up to 14 animals (usually mostly female). Sub-adult bulls will congregate, often in association with an adult cow. Most adult bulls are solitary. Dominant bulls mark their territory with excrement and urine. The dung is laid in well defined piles. It may have 20 to 30 of these piles to alert passing white rhinos that it is his territory. Another way of marking their territory is wiping their horns on bushes or the ground and scraping with their feet before urine spraying. They do this around ten times an hour while patrolling territory. The same ritual as urine marking except without spraying is also commonly used. The territorial male will scrape-mark every or so around its territory boundary. Subordinate males do not mark territory. The most serious fights break out over mating rights with a female. Female territory overlaps extensively, and they do not defend it. Reproduction Females reach sexual maturity at 6–7 years of age while males reach sexual maturity between 10 and 12 years of age. Courtship is often a difficult affair. The bull stays beyond the point where the cow acts aggressively and will give out a call when approaching her. The bull chases and or blocks the way of the cow while squealing or wailing loudly if the cow tries to leave his territory. When ready to mate the cow curls her