This study begins by discussing how density dependence is well understood in temperate regions but few studies have been conducted in tropical regions where there are many limiting resources such as food and water. Elephant populations in southern Africa have reached unprecedented levels because of conservation efforts. However, as populations rise, the availability of resources is reduced. Competition for resources leads to a negative feedback system between population size and population growth. Researchers believe identifying the interactions between resource availability, aggregation levels and population size will allow them to better understand density dependence. Researchers also believe that the elephant biomass is related to the mean annual rainfall, which suggests a relationship between elephants and their resources. In this study, the world’s largest elephant population in Hwange National Park in Zimbabwe was the group of interest. With research beginning 1967 and ending in 2005, data was collected from 45 watering holes from across the park. Researchers studied changes in the abundance of elephants with regard to rainfall to see if resources affected their populations. The population of elephants increased, doubling in size since culling ceased and also due to immigration. However, population growth rates were negatively related to population density. Growth rates and density had a convex relationship. Growth rates were also negatively related to population density on annual rainfall by a linear relationship. Researchers concluded that elephant populations decreased during dry years when rainfall was little and the elephant density was high. During dry years there were few waterholes that retained water and therefore the number of