Prey preference and dietary overlap between the aardvark and Temminck's pangolin in the kalahari

Abstract

The aardvark (Orycteropus afer) and Temminck's pangolin (Smutsia temminckii; hereafter pangolin) feed on ants and termites. Previous research in the Kalahari (Tswalu Kalahari Reserve) in southern Africa has indicated that the diet of the two species does not overlap, with aardvark preying predominantly on harvester termites (Hodotermes mossambicus) and pangolin preying predominantly on ants (mainly Crematogaster spp). However, the research on each species was conducted at different times, so the dietary differences might have been due to various factors that differed between the study periods. We therefore studied the diet of aardvark and pangolin simultaneously by analysing faecal samples that were collected from the two species over 1 year at Tswalu Kalahari Reserve. We used pitfall trapping to assess the relative abundance of ant prey species bimonthly; however, this method was ineffective for sampling termites. Termite abundance was inferred from their widespread presence in aardvark diets and visible termite activity at the study site. Aardvark preyed predominantly on Trinervitermes termites in spring (88 %) and summer (43 %), and Hodotermes termites in autumn (50 %) and winter (47 %), while pangolins fed primarily on Crematogaster ants in spring (62 %) and winter (51 %), and Anoplolepis ants in summer (60 %) and autumn (48 %). Although Anoplolepis and Crematogaster are commonly consumed, they were not frequently captured in pitfall traps, representing only 16.4% and 1.5% of the ant species collected, respectively. Pianka's index revealed that there was considerable overlap in dietary niche between the two mammals when resources were abundant in summer (60 %) and autumn (73 %), but less dietary overlap when resources became scarcer in winter (45 %) and spring (44 %). Less dietary overlap when resources are scarce likely reduces direct competition between these two myrmecophagous species, but it is also possible that differences in foraging over time and space may allow the aardvark and pangolin to coexist while exploiting the same food resources. Our study was conducted during an unusually wet year in the Kalahari, so whether niche partitioning occurs to the same extent in drier years remains to be determined.