Short communication: Abundance, distribution and population trends of Nile crocodile (&lt;i&gt;Crocodylus niloticus&lt;/i&gt;) in Gonarezhou National Park, Zimbabwe

E Gandiwa,H Van Der Westhuizen,J Jakarasi,J Muvengwi,P Zisadza-Gandiwa

doi:10.4314/wsa.v39i1.16

Short communication: Abundance, distribution and population trends of Nile crocodile (<i>Crocodylus niloticus</i>) in Gonarezhou National Park, Zimbabwe

E Gandiwa, H Van Der Westhuizen + Show 3 more

Open Access

https://doi.org/10.4314/wsa.v39i1.16

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Abstract

The Nile crocodile ( Crocodylus niloticus ) is an iconic or keystone species in many aquatic ecosystems. In order to understand the abundance, distribution, and population trends of Nile crocodiles in Gonarezhou National Park (GNP), southeastern Zimbabwe, we carried out 4 annual aerial surveys, using a Super Cub aircraft, along 3 major rivers, namely, Save, Runde and Mwenezi, between 2008 and 2011. Our results show that Runde River was characterised by a significant increase in Nile crocodile abundance whereas both Save and Mwenezi rivers were characterised by non-significant increases in Nile crocodile abundance. Overall, we recorded a significant increase in total Nile crocodile population in the three major rivers of the GNP. The non-significant increase in Nile crocodiles in the Mwenezi and Save rivers was likely due to habitat loss, through siltation of large pools, and conflicts with humans, among other factors. We suggest that GNP management should consider halting crocodile egg collection in rivers with low crocodile populations and continuously monitor the crocodile population in the park. Keywords: Abundance, aerial survey, Nile crocodile, population, river, Zimbabwe

Highlights

The Nile crocodile (Crocodylus niloticus, Laurenti 1768) is among the largest and best known biologically of all the crocodilians (Martin, 2008; Fergusson, 2010; Leslie et al, 2011)
Aerial surveys were used in gathering data on crocodiles in Gonarezhou National Park (GNP)’s 3 major rivers, namely, Save, Runde and Mwenezi
Our results show that GNP has a relatively low crocodile population, with most of the crocodiles being concentrated in Runde River relative to the other two major rivers

Summary

Introduction

The Nile crocodile (Crocodylus niloticus, Laurenti 1768) is among the largest and best known biologically of all the crocodilians (Martin, 2008; Fergusson, 2010; Leslie et al, 2011). Nile crocodiles are ectothermic and regulate their body temperature behaviourally by moving between sun-exposed sandbanks and the water (Leslie et al, 2011). Top predators such as crocodiles often reflect ecosystem degradation (Ferreira and Pienaar, 2011), and are worth monitoring in protected area systems

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