THE INTERACTIONS AND RELATIONSHIPS OF MAL ES OF COMMON (CLETHRIONOMYS-GLAREOLUS) AND NORTHERN (CLETHRIONOMYS-RUTILUS) REDBACKED VOLES UNDERFIRST MEETINGS IN EXPERIMENTAL GROUPS

The behavior of common and northern redbacked voles in two-species gro ups (2 females and 4 males of each species in each group) were studied in 120 sq. m enclosures. In 13 cases the voles were previously mainta ined in monospecific groups throughout a month. 3 two-species groups w ere formed by simultaneous housing of all voles in the enclosure. Obse rvations were carried out on 1, 3, 5, 8, 11, 14, 17 and 20th days over a 10-hour nightlong period (1290 hours in all). All interactions and types of activity of tile voles were recorded, 11200 contacts includin g 4500 interspecific ones were analyzed. No considerable differences b etween the searching behavior of northern and common redbacked voles a t a new territory were found. The interactions of the animals of diffe rent species under the first meetings were similar to those of conspec ific animals in analogous situation. The greatest number of interspeci fic interactions of males could be considered as either aggression or avoidance. The hierarchical structure of the males in mixed groups of northern and redbacked voles was similar to intraspecific social struc ture. A male of either of two species could become a dominant. The soc ial rank of a male in two-species systems depend to a large extent on its rank in monospecific group, The dominant individual was the main i nitiator of both intra- and interspecific aggressive interactions. Hie rarchical structure in the groups formed by simultaneous housing of ti le volts was less stable.