Factors that influence population density include environmental conditions, resource availability, and social behavior of species. Resources such as food, water, and shelter can limit or promote population growth, while competition for these resources also plays a key role. Additionally, predation, disease, and climate can affect survival rates and reproductive success, shaping population dynamics. Social structures, such as group living or territoriality, can influence how individuals distribute themselves within a habitat, impacting overall density levels in particular environments.