Tree cavity is an important breeding- and nesting-site for mammals and birds. Thus, these animals often separate the use of the cavity, partially or completely. For example, the small Japanese field mouse Apodemus argenteus nests in low height cavity to avoid competition with Siberian flying squirrel Pteromys volans (Suzuki and Yanagawa 2012, Suzuki et al. 2014). In addition, Slagsvold (1978) showed importance of different breeding season between the pied flycatcher Ficedula hypoleuco and great tit Parus major for breeding success of the flycatcher by suggesting frequently attack of the tits on the flycatchers. In this wise, cavity users’ interaction is important information for accurately understanding cavity breeding ecology, and numerous
