Feeding ecology and diet

African mole-rats favor areas in which energy-rich bulbs, corms, and tubers abound. Although these constitute their main food source, they will also eat roots and the aerial parts of plants. These geophytes often occur in clumps and are encountered by the mole-rats as they dig their foraging tunnels, most of which are dug after rain when the soil is moist and easily worked. In arid regions where rainfall is unpredictable and often widely spaced, the mole-rats have to make the most of each digging opportunity in order to find sufficient food to last them until it next rains (sometimes a year later). Clumps of food in these arid regions also tend to be spaced further apart than in mesic regions, or to occur as large isolated tubers. The limited opportunities in which to dig, and the distribution of food in these arid regions, exclude solitary species from these areas. Social species can mobilize their workforce

The dune mole-rat (Bathyergus janetta) primarily uses its claws to dig. (Photo by J. Visser/Mammal Images Library of the American Society of Mammalogists.)

to search a wide area in a short time to locate sufficient food to see them through the dry periods. Colonies of naked and Damaraland mole-rats have been known to dig up to 0.6 mi (1 km) in a single session of digging after a rainfall.

Small-sized geophytes are either immediately consumed or carried to a central store situated near the nest. Large geo-phytes are left growing and eaten in situ. Sometimes these partly eaten geophytes are abandoned, then they regenerate, and thus provide the mole-rats with a renewable resource. This is important because field studies on the naked molerat, Damaraland mole-rat, and the common mole-rat show that colonies remain resident in an area; they do not simply exploit it and then move on. The diet of dune mole-rats includes about 60% aboveground vegetation (forbs, grasses); the mole-rats come up under a plant, loosen its roots, and pull the entire plant into the burrow. They can thus forage with minimal exposure to predators.

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