Using simulations of past and present elephant (Loxodonta africana) population numbers in the Okavango Delta Panhandle, Botswana to improve future population estimates

Abstract

An ability to reliably estimate population numbers, trends and densities of wildlife has a prominent role in conservation and management of wetlands. We use aerial surveys and simulation techniques to explore the results of past and present elephant population surveys in the Okavango Delta Panhandle, Botswana, and use these to propose a technique of simulation to improve counts in the future. Population numbers and density estimates from past survey results show large fluctuations, which are unlikely to come from reproduction. Reasons for such variations could be attributed to imprecision in survey techniques or may be because only part of the elephant range is being surveyed. Simulated surveys of hypothetical elephant populations were used to explore the effect of different survey techniques, spatial distributions of animals and spatial scale on the precision of aerial survey population estimates and trends. Our study reveals the usefulness of using simulations to test the reliability of survey data and plan more efficient surveys. We also find that while there may be some uncertainty in individual population estimates, there is more certainty in the recorded trends. These findings reinforce the need to address elephant management in the Okavango and surrounding wetland systems and call for the urgent consideration of management strategies such as fence realignments to affect the objectives of the Kavango Zambezi Transfrontier Conservation Area (KAZA TFCA) initiative, which will help relieve elephant population pressure.

Size, shape and maintenance matter: A critical appraisal of a global carnivore conflict mitigation strategy – Livestock protection kraals in northern Botswana

“…An alternative may be to build kraals as 'Living Walls' by planting indigenous thorny trees (Lichtenfeld et al, 2015). This could address deterioration of materials and reduce maintenance needs, however would require effective sapling protection from increasing elephant (Songhurst et al, 2015) and livestock populations for several years. This expectation appears unrealistic, given the observed lack of maintenance.…”

Chilli-briquettes modify the temporal behaviour of elephants, but not their numbers

“…The eastern Panhandle has one of the largest populations of elephants in the country, with > 18,000 individuals (Songhurst, 2016), who remain close to the river throughout the year (Pozo et al, unpubl. data).…”

Exploring movement decisions: Can Bayesian movement‐state models explain crop consumption behaviour in elephants (Loxodonta africana)?

“…We collected data in the eastern panhandle of the Okavango delta; an 8,732 km 2 area between the Namibian border fence, the northern buffalo fence and the Okavango River ( Figure 1). The elephant population in this area is estimated to be around 18,000 individuals (Songhurst, 2016), with an average growth rate of 9.5% per year (Songhurst, Chase, & Coulson, 2015). Along the Okavango River, there are 13 villages with ca.…”