The feeding ecology of the aardvark Orycteropus afer - ResearchGate

140 W. A. TAYLOR ET AL.Table 1. The overall contents of aardvark faecal samples at TdR from 1996to1998 (standard deviation in parentheses). Mean % were calculated from 12individual aardvarks and a total of 350 faecal samples. They were calculated in thefollowing way: for each faecal sample, species numbers were converted into percentagesand an average obtained from all samples for each aardvark. These were thenclumped with other aardvark averages to give the overall average. % occurrence is thepercentage of faecal samples in which a prey species was foundMean % Range % Occurrence IVAnoplolepis spp. 68)4 (27)1) 0–100)0 95)8 65)50Monomorium albopilosum 7)4 (11)8) 0–92)2 78)6 5)81Dorylus helvolus 2)8 (11)1) 0–90)3 23)9 0)67Messor capensis 1)1 (3)3) 0–35)3 55)1 0)61Formicidae sp. 1 0)4 (1)3) 0–11)6 17)7 0)07Crematogaster spp. 0)4 (3)3) 0–50)4 8)5 0)03Camponotus spp. 0)3 (1)2) 0–16)4 27)4 0)08Other species 0)3 (1)7) 0–27)7 15)5 0)05Solenopsis punctaticeps 0)3 (2)7) 0–34)2 4)5 0)01Monomorium havilandi 0)1 (0)4) 0–3)4 46)6 0)05Pheidole spp. 0)1 (0)1) 0–1)1 7)5 0)01Formicidae sp. 2 0)1 (0)5) 0–4)3 7)0 0)01Formicidae sp. 3 0)1 (0)4) 0–6)9 6)7 0)01Trinervitermes trinervoides 15)3 (22)3) 0–98)9 82)5 12)63Hodotermes mossambicus 2)9 (10)6) 0–100)0 44)4 1)29Importance value (IV)"(Mean % * % Occurrence)/100.Table 4 shows average monthly variation in aardvark faecal contents for one year. Inevery month Anoplolepis spp. were the most abundant prey, followed by T. trinervoidesand M. albopilosum. Within all species there was considerable variation between monthsbut there were no apparent seasonal patterns.Seasonal differences in the predation of A. custodians and T. trinervoides weretested statistically. May, June and July data were clumped as winter, while November,December and January data made up summer. Average percentages from nine aardvarkswere used. For Anoplolepis spp. there was no seasonal difference (t"0)84,df."16, p"0)41), while for T. trinervoides there was evidence for a seasonal difference(albeit not at the 0)05% level) (t"2)02, df."16, p"0)06). In winter aardvarksate more T. trinervoides than summer.In 1997 T. trinervoides comprised an average of 64% soldiers and 36% workers in thefaeces. Worker numbers increased in winter then decreased again in the followingsummer. January and December had the lowest proportions of workers (25% and 24%respectively) while the winter months May to July had an average of 39%. October wasthe only month when workers outnumbered soldiers (54% workers).Soldiers occurred in the faeces in larger numbers than expected (χ 2 "3184, df."1,p(0)001). Expected values were calculated by multiplying the percentage of a casteavailable (25% soldiers, 75% workers) (Adam, 1993) by the total number of soldiers andworkers in the faeces.Feeding observationsAt TdR aardvarks fed at night and exclusively from ant and termite nests. Ground feedsfor ants were mostly 5–30 cm deep, while digs as deep as 2 m were observed for the