<p>The characteristics of the ecology of the sibling species <i>M.</i> (<i>T.</i>) <i>majori</i> and <i>M.</i> (<i>T.</i>) <i>daghestanicus</i> in their contact places in some areas of the Greater and Lesser Caucasus are considered. An analysis of symbiotopic samples of the sibling species from two localities in the Karachai-Cherkessia (right bank of the Kizgich River and the vicinity of the rural settlement Verkhnii Arkhyz) and a mixed sample from the zone of sympatry in the vicinity of the rural settlement of Ankavan in Armenia was performed. The obtained primary data make it possible to assert that an important condition for coexistence of the sibling species <i>M.</i> (<i>T.</i>) <i>majori</i> and <i>M.</i>&#xa0;(<i>T.</i>) <i>daghestanicus</i> is their separation by occupancy stations, as well as by a number of environmental characteristics. Differences in characteristics of the population structure (age and sex composition), as well as in the reproduction strategy, allow sibling species of pine voles of the Caucasus to coexist in their contact places, even under symbiotopy conditions. Consideration is given to the previously known craniometrical characters, confirming the differences between sibling species of pine voles of the Caucasus in the nutritional adaptations, which may also be one of the factors providing for their coexistence at their contact places.</p>