Elephant population responses to increased density in Kruger National Park
The elephant population in the Kruger National Park (KNP) has been increasing since the cessation of culling in the mid-1990s. This contrasts with recent trends in elephant populations in many parts of Africa where poaching continues to decrease numbers. Logistic growth theory predicts that increase...
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doaj-eaf786c6526b4e78bf1378339998cf412021-07-02T08:43:59ZengAOSISKoedoe: African Protected Area Conservation and Science0075-64582071-07712021-06-01631e1e1310.4102/koedoe.v63i1.16601257Elephant population responses to increased density in Kruger National ParkAlbertus S. Louw0Sandra MacFadyen1Sam Ferreira2Cang Hui3Department of Mathematical Sciences, Faculty of Natural Sciences, Stellenbosch University, StellenboschDepartment of Mathematical Sciences, Faculty of Natural Sciences, Stellenbosch University, StellenboschConservation Services, South African National Parks, SkukuzaDepartment of Mathematical Sciences, Faculty of Natural Sciences, Stellenbosch University, Stellenbosch, South Africa; and Department of Theoretical Ecology Group, African Institute for Mathematical Sciences, Cape TownThe elephant population in the Kruger National Park (KNP) has been increasing since the cessation of culling in the mid-1990s. This contrasts with recent trends in elephant populations in many parts of Africa where poaching continues to decrease numbers. Logistic growth theory predicts that increased competition for vital resources when densities increase should serve to constrain population growth, implying a negative density-growth correlation. We tested this prediction using 28 years of elephant census data to investigate how the growth of the KNP’s elephant population responds to increasing elephant density from the period 1985 to 2012. We expected a spatially variable population growth pattern in response to the distribution of elephant densities in the park and thus classified the park into zones with low, medium or high long-term (28 years) average, dry-season elephant density. Zones were named ‘peripheral’, ‘semi-peripheral’ and ‘core’ zones, respectively, and represent proxies of resource availability to elephant herds. Using a Stochastic Ricker growth model, we tested for the presence of negative density-dependence in population growth in the core versus peripheral zones. In response, we only detected density-dependent growth in the core zone. Overall the population grew at 4.1% per year, coupled with local recruitment rates that increased over time, particularly in the peripheral zones. These density-dependent trends support previous observations of homogenisation of elephant distribution and density across the KNP landscapes. Conservation implications: Density-dependent changes to elephant growth rates are scale-dependent (local vs. park level). Only core areas with long-term high density show signs of density-dependent growth. Overall, the distributions of elephants are homogenising in the KNP. Conservation authorities should monitor the impact of such homogenisation to landscape heterogeneity. The spatial variation of the negative density-growth correlation, especially between the core and peripheral zones, can be considered when developing effective strategies to manage the KNP elephant population.https://koedoe.co.za/index.php/koedoe/article/view/1660african elephants loxodonta africanapopulation growthdensity dependencespatial distributionsconservation management. |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Albertus S. Louw Sandra MacFadyen Sam Ferreira Cang Hui |
spellingShingle |
Albertus S. Louw Sandra MacFadyen Sam Ferreira Cang Hui Elephant population responses to increased density in Kruger National Park Koedoe: African Protected Area Conservation and Science african elephants loxodonta africana population growth density dependence spatial distributions conservation management. |
author_facet |
Albertus S. Louw Sandra MacFadyen Sam Ferreira Cang Hui |
author_sort |
Albertus S. Louw |
title |
Elephant population responses to increased density in Kruger National Park |
title_short |
Elephant population responses to increased density in Kruger National Park |
title_full |
Elephant population responses to increased density in Kruger National Park |
title_fullStr |
Elephant population responses to increased density in Kruger National Park |
title_full_unstemmed |
Elephant population responses to increased density in Kruger National Park |
title_sort |
elephant population responses to increased density in kruger national park |
publisher |
AOSIS |
series |
Koedoe: African Protected Area Conservation and Science |
issn |
0075-6458 2071-0771 |
publishDate |
2021-06-01 |
description |
The elephant population in the Kruger National Park (KNP) has been increasing since the cessation of culling in the mid-1990s. This contrasts with recent trends in elephant populations in many parts of Africa where poaching continues to decrease numbers. Logistic growth theory predicts that increased competition for vital resources when densities increase should serve to constrain population growth, implying a negative density-growth correlation. We tested this prediction using 28 years of elephant census data to investigate how the growth of the KNP’s elephant population responds to increasing elephant density from the period 1985 to 2012. We expected a spatially variable population growth pattern in response to the distribution of elephant densities in the park and thus classified the park into zones with low, medium or high long-term (28 years) average, dry-season elephant density. Zones were named ‘peripheral’, ‘semi-peripheral’ and ‘core’ zones, respectively, and represent proxies of resource availability to elephant herds. Using a Stochastic Ricker growth model, we tested for the presence of negative density-dependence in population growth in the core versus peripheral zones. In response, we only detected density-dependent growth in the core zone. Overall the population grew at 4.1% per year, coupled with local recruitment rates that increased over time, particularly in the peripheral zones. These density-dependent trends support previous observations of homogenisation of elephant distribution and density across the KNP landscapes.
Conservation implications: Density-dependent changes to elephant growth rates are scale-dependent (local vs. park level). Only core areas with long-term high density show signs of density-dependent growth. Overall, the distributions of elephants are homogenising in the KNP. Conservation authorities should monitor the impact of such homogenisation to landscape heterogeneity. The spatial variation of the negative density-growth correlation, especially between the core and peripheral zones, can be considered when developing effective strategies to manage the KNP elephant population. |
topic |
african elephants loxodonta africana population growth density dependence spatial distributions conservation management. |
url |
https://koedoe.co.za/index.php/koedoe/article/view/1660 |
work_keys_str_mv |
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