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Foraging strategies of co-existing lacertid lizards in the arid Tankwa Karoo Basin of South Africa

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Author(s): Johan du Plessis | leFras Mouton

Journal: African Zoology
ISSN 1562-7020

Volume: 47;
Issue: 1;
Date: 2012;
Original page

Keywords: resource partitioning | foraging strategy | movements per minute | proportion time spend moving | proportion of attacks on prey whilst moving | Pedioplanis laticeps

ABSTRACT
Four lacertid lizards, Pedioplanis laticeps, P. lineo-ocellata, Meroles knoxii and Nucras tessellata, occur sympatrically on the arid plains of the Tankwa Karoo Basin in South Africa. The aim of this study was to evaluate the significance of foraging strategy in resource partitioning among the four species, allowing them to co-occur in a structurally simple system with a limited number of potential niches. Previous workers already identified P. lineo-ocellata and M. knoxii as sit-and-wait foragers and N. tessellata as an active forager. We recorded data on three foraging variables: movements per minute, proportion of time spent moving, and proportion of attacks on prey whilst moving, for juveniles and adults of P. laticeps. By comparing the foraging data obtained for P. laticeps to those for other lacertid species, we were able to demonstrate that adult P. laticeps are ambush foragers. We also noted a significant ontogenetic shift in foraging behaviour in P. laticeps, and, due to a significantly higher frequency of short brief movements, we classified juveniles as mixed foragers. The sharing of an ambush foraging strategy by at least three of the four lacertid species co-occurring on the Tankwa plains, suggests considerable overlap along the trophic dimension of ecological space. We concluded that this overlap will preclude syntopic occurrence of the three ambush foragers in the Tankwa Karoo Basin.

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