DEMOGRAPHIC AND REPRODUCTIVE ATTRIBUTES OF DISPERSERS IN 2 POPULATIONS OF THE SUBTERRANEAN RODENT CTENOMYS-TALARUM (TUCO-TUCO)

The demographic and reproductive characteristics of dispersers in the fossorial rodent Ctenomys talarum, the tuco-tuco, were studied by remo ving animals from two experimental plots. Data on dispersers' attribut es were compared with those of resident and transient individuals from previous capture-mark-release and removal studies performed in the sa me localities. Average weekly dispersal by tuco-tucos was 2.38% (range 0-5.75%) at Necochea and 5.75% (range 0-15.75%) at Mar de Cobo. The l ow proportion of dispersers reflects their fossorial habit. At Mar de Cobo, the sex ratios of dispersers and transients showed a 1:1 relatio nship, whereas residents showed an excess of females. All groups did n ot differ from a sex ratio of 1:1 at Necochea. At both localities, dis persers did not differ qualitatively from residents in age composition , litter size, or body mass. Transients and dispersers of both populat ions were characterized by a higher proportion of immature individuals than residents. We conclude that dispersal may be an important factor regulating the C. talarum population and may counteract the restricti ons imposed by its subterranean habitat.