The historical ecology of the large mammal populations of Ngorongoro Crater, Tanzania, east Africa

Abstract

Abstract Ngorongoro Crater is an ecologically important protected area in Tanzania, east Africa. We review published and unpublished data on the crater's large mammal community from the first recorded visit by a European in 1892 to 2010. Early estimates often exaggerated large herbivore numbers and regular scientific censuses have only been made since the 1960s. Since then, most large herbivore populations have declined, particularly wildebeest Connochaetes taurinus, which have been replaced by buffalo Syncerus caffer as the dominant herbivore in terms of biomass. The internationally important population of black rhinoceros Diceros bicornis has reduced from over 100 in the 1960s to around 30 in 2011. The lion Panthera leo population is genetically isolated, has declined since the 1960s and has consistently been held below carrying capacity. Buffalo and warthogs Phacochoerus aethiopicus are relatively recent colonizers. Wild dogs Lycaon pictus were present in the 1960s but are probably now absent. Small numbers of elephants Loxodonta africana use the crater floor and cheetahs Acinonyx jubatus appear to be intermittent visitors. Primary drivers of changes in herbivore populations are disease and vegetation change. Poaching has been implicated as the cause of decline in rhinoceros. Disease associated with anomalous weather conditions appears to be the main driver for population change in lions. Recent scientific research on the large mammal community has largely been focused on lions and rhinoceros. The output of research on other species has not increased since the 1960s. A wider dissemination of research on the crater's mammal populations would help to secure its status as an important site for conservation in the eyes of the wider scientific and conservation community.