Spalacopus cyanus (Rodentia : Octodontidae): an extremist in tunnel constructing and food storing among subterranean mammals

Burrow systems of two coastal populations (El Alamo and Los Maitenes) of th e social octodontid rodent Spalncopus cyanus were studied in central Chile. Tunnel systems were estimated to be up to 600 m long, ran at a depth of 15 cm and had a diameter of 6 cm. Tunnel openings were usually unplugged, and a minor preference toward southern and south-eastern direction of entrance s was apparent. Nests, frequently found in the root system of Berberis acti nacantha at a depth of 30 cm, consisted of grasses, roots and plastic bags. Nests serve for sleep, care of the pups and as latrines. Many staphylinid beetles of the genus Edrabius and other invertebrates were found in the bre eding nests. Food chambers contained up to 13.2 kg of bulbs of the geophyte Dioscorea longipes collected by a single colony consisting of 26 animals ( including 10 adults) and were frequently found at El Alamo. However, no bul bs were found at Los Maitenes, where the coruros forage above ground on lea ves of Convolvulus arvensis within a radius of about 10 cm of the entrances . Apparently, the burrow design is also affected by food availability, soil quality, and colony size.