Z. Säugetierkunde 57 (1992) 163-168 © 1992 Verlag Paul Parey, Hamburg und Berlin ISSN 0044-3468 Burrow structure in the subterranean rodent Ctenomys talarum By C. D. Antinuchi and Cristina Busch Departamento de Biologia, FCEyN, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina Receipt of Ms. 4. 6. 1991 Acceptance of Ms. 30. 10. 1991 Abstract Analysed the structure of completely excavated burrow Systems of Tuco-tuco (Ctenomys talarum). Burrow Systems of males and females show the same basic design. The main tunnel occupies 48 % of a burrow in total length and is formed by basic units (interfork distances) of 0.9 ± 0.4 m. Subterranean plant biomass was correlated with burrow length and with the number of branches. Soil granulometry affected the diameter and depth of tunnels and soil humidity was correlated with the main tunnel length. Introduction South-American caviomorph rodents of the genus Ctenomys, called Tuco-tucos are the most numerous in species number of all fossorial rodents (Reig et al. 1990). Tuco-tucos spend most of their lives within plugged burrows, evident by the mounds that result from pushing loosened soil out of the tunnels. Burrow structure is of main importance in terms of energy costs or burrowing. As a consequence, foraging efficiency and escape from predators are the ultimate factors shaping burrowing behavior (Andersen 1988). Thus, burrows of different mammalian taxa have evolved into broadly convergent structures. Studies on burrow architecture of North American geomyd rodents suggest that subterranean rodents maximize the energy expended per meter of burrow (Vleck 1981) and that architecture of burrow Systems is not adaptive to resource availability (Cameron et al. 1988). Reichman et al. (1982) reported that total length of the burrow and the average number of branches are inversely related to plant productivity. Furthermore, these authors suggest that any spacing rule involves basic building units of the burrow System. This unit can be combined in such a way as to increase overall burrow length in response to resource availability. The literature contains little Information concerning the structure of Tuco-tuco burrow Systems, although numerous studies have centered on those of the northern pocket- gopher. For a review on subterranean burrow structures, see Hickman (1990). The present report offers information based on field observations on the structure of completely excavated burrow Systems of the Tuco-tuco, Ctenomys talarum, and relates the major features of the burrow with characteristics of the surrounding habitat. Material and methods This study was conducted from January to December 1989 at the sandy dune belt from Mar del Cobo (Pdo. Mar Chiquita, Prov. Buenos Aires). Plastic live traps were set at fresh surface mounds. Weight and sex of the Tuco-tuco trapped were recorded. Burrow Systems were excavated with a shovel. Tunnels, Chambers and mounds were mapped on graph paper. The length of all tunnels in the entire burrow System of each individual Tuco-tuco was measured from the maps and the total above area covered by each individual was also measured from the maps using the minimum convex polygon U.S. Copyright Clearance Center Code Statement: 0044-3468/92/5703-163 $ 02.50/0 © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/