Surface‐mound formation by the Tuco‐tuco, Ctenomys fulvus (Rodentia: Ctenomyidae), with comments on earth‐pushing in other fossorial mammals

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Abstract
Surface‐mound formation by Ctenomys fulvus (and evidently most Ctenomyidae, an autochthonous South American family) differs from most other fossorial mammals in that soil is transported to the surface by kicking with the hind feet (a habit shared with most Bathyergidae. the African mole‐rats). The greatly enlarged hind feet of Ctenomys are the largest for any terrestrial fossorial group. The eyes of Ctenomys, also different from many mole types, are large and appear better protected by hind foot soil‐pushing. The manner in which the stocky tail of Ctenomys supports the body above the substratum while kicking synchronously with the hind feet is unusual for any mammal.The body facing forward while pushing soil, the position favoured by most mole‐types, allows for the scanning of the surface for predators and defence through the use of teeth, claws and direct vocalizing, while hind foot soil‐pushing conserves energy by negating the need to turn around in the tunnel after digging, and again after depositing soil on the surface. Studies are required to determine the efficiency of various predators on the capture of mole‐types as soil is being pushed on to the surface, perhaps the most significant selective pressure on the manner of pushing soil.