Trends in populations of elephant and other large herbivores in Gonarezhou National Park, Zimbabwe, as revealed by sample aerial surveys

Abstract

For 30 years, regular aerial surveys in Zimbabwean protected areas were funded, designed and executed primarily to estimate elephant numbers. Other large herbivores were recorded, even though some species were not easily seen from the air in savannah woodlands. Population estimates for species other than elephant provided indices of abundance that could be used to determine temporal trends in population size. This study tests for significant trends in the abundance of large herbivores in Gonarezhou National Park, assuming that data from aerial sample surveys designed for elephant also provide accurate estimates of real trends in the populations of other herbivores. For each species, the exponential rate of population change was calculated using weighted regression, with the variance of this rate based on the sampling variances of the population estimates. Significant population trends were detected for eight species. Before the 1992 drought, elephant number was held approximately constant by frequent culls, but afterwards, it increased at a mean annual rate of 6.2% (confidence limits 4.0% and 8.6%). Elephants in cow herds increased at 7.3%, significantly faster than elephants in bull herds (−0.5%). Buffalo, eland, kudu, nyala, waterbuck, wildebeest and zebra all increased in number, after population declines during the drought.

Status of African baobab (<i>Adansonia digitata</i>) across Gonarezhou National Park, Zimbabwe

“…4314/jasem.v18i1.18 Although precipitation may be the primary determinant of vegetation biomass in dry savanna ecosystems (Deshmukh 1984;Prins and Loth 1988;Sankaran et al 2005), in Gonarezhou National Park (hereafter, Gonarezhou), disturbances, such as herbivory, mainly from African elephant (Loxodonta africana) herbivory on baobabs (Adansonia digitata), droughts, fires and human activities may also likely influence baobab woodlands (Tafangenyasha 1997;Mpofu et al 2012;Kupika et al 2014). Between the year 1980 and 2012, elephant population in Gonarezhou increased from approximately 4700 to 9125 (Dunham 2012). Taken with the results of other aerial elephant surveys conducted post 1992 drought, elephants in Gonarezhou have increased at a mean annual rate of 6% during the past sixteen years.…”

Trends in Illegal Killing of African Elephants (Loxodonta africana) in the Luangwa and Zambezi Ecosystems of Zambia

“…Based on 2012 population estimates by Frederick (2013) combined with the MIKE data, we derive 5.17% elephant-carcass ratio in South Luangwa MIKE area. This maybe unsustainable as it exceeds the natural elephant population growth rate of 5% (Dunham, 2012;CITES et al, 2013). Based on the 2012 aerial survey results of the Lower Zambezi (Viljoen, 2013), the calculated elephant carcass ration is 2.68%.…”

Relationship between burden of infection in ungulate populations and wildlife/livestock interfaces

“…Buffalo density in the northern part of KNP is higher than in the GNP (1·4 vs. 0·5 buffalo per km 2 ) [28,29]. In informal interviews, Pesvi farmers indicated that buffalo were regularly seen crossing from KNP into Zimbabwe.…”