Abstract:
In the Western Cape three species of mole-rat occur in sympatry, however, little is known about differences in their dietary
preferences. Dietary composition of the three species; the common mole-rat (Cryptomys hottentotus hottentotus), the Cape
mole-rat (Georychus capensis) and the Cape dune mole-rat (Bathyergus suillus) were examined using stable isotope analysis.
Blood, fur and claw samples were collected from 70 mole-rats, in addition to several potential food items, to assess food
selection of the three species under natural conditions. Overall there was a significant difference in the isotopic composition
(d13C and d15N) between all three species and significant differences in their diet composition. There were also significant
differences between tissues in all three species suggesting temporal variation in diet. The small size and colonial lifestyle of
C. h. hottentotus allows it to feed almost 100% on bulbs, while the solitary and larger species G. capensis and B. suillus fed to
a greater extent on other resources such as grasses and clover. B. suillus, the largest of the species, had the most generalized
diet. However, overall all species relied most heavily upon geophytes and consumed the same species suggesting
competition for resources could exist. We also showed a high level of individual variation in diet choices. This was most
pronounced in B. suillus and G. capensis and less so in C. h. hottentotus. We demonstrate that stable isotope analysis can
successfully be applied to examine dietary patterns in subterranean mammals and provide insights into foraging patterns
and dietary variation at both the inter and intra population level.
