740 Bulgarian Journal of Agricultural Science, 22 (No 5) 2016, 740–744 Agricultural Academy ATTRACTION–AVOIDANCE RESPONSE OF MOUND-BUILDING MOUSE, MUS SPICILEGUS IN AGROECOSYSTEMS TO CONSPECIFIC AND HETEROSPECIFIC ODOURS D. SIMEONOVSKA-NIKOLOVA Sofia University “St. Kl. Ohridski”, Department of Ecology and Protection of Nature, Faculty of Biology, BG-1164 Sofia, Bulgaria Abstract SIMEONOVSKA-NIKOLOVA, D., 2016. Attraction-avoidance response of mound-building mouse, Mus spicilegus in agroecosystems to conspecific and heterospecific odours. Bulg. J. Agric. Sci., 22: 740–744 The behavioral responses of male mound-building mice Mus spicilegus to odours from males of their own species and odors from males of another species – house mouse Mus musculus musculus and yellow-necked mouse Apodemus flavicollis were studied in an attraction–avoidance test in order to clarify the role of odour in their relationships in wild populations in ag- ricultural land. The experiments were carried out in the breeding season. M. spicilegus males showed attraction to conspecific odours from the same sex, but indifference to heterospecific odours of male M. m. musculus, and avoidance to odours of male A. flavicollis. The behavioural responses to conspecific and heterospecific odours are discussed in terms of attractiveness of odour cues, according to their significance in social relationships and spacing behaviour. Key words: behavioural response, odour discrimination, olfactory cues, Mus, Apodemus, competition *E-mail: mammals@abv.bg Introduction Rodents often colonise agricultural lands. In the region of North Bulgaria the mound-building mouse, Mus spicilegus is a species adapted to agroecosystems. At the beginning of autumn, mound-building mice build complex mounds and supply them with seeds. In these mounds, they spend the winter (Figure1). In spring, mound-building mice leave the mound and begin to reproduce in agricultural fields (Orsini et al., 1983; Milishnikov et al., 1998; Sokolov et al., 1998; Simeonovska-Nikolova, 2007a; Poteaux et al., 2008). In the region M. spicilegus is sympatric with Mus musculus mus- culus during the spring-autumn period (Orsini et al., 1983; Bonhomme et al., 1984; Sokolov et al., 1998). At the be- ginning of autumn M. m. musculus returns to houses, where it spends the winter. Acording to Sokolov et al. (1998) and Dobson, Baudoin (2002) from spring to autumn, mound- building mice and house mice may be found in the same habitats, but little is known about their interspecific relation- ships. Besides, M. spicilegus and wood mice Apodemus fla- vicollis and/or Apodemus sylvaticus are often dominant spe- cies in communities of small mammals in agroecosystems of North Bulgaria. Often wood mice are found close to mounds of M. spicilegus, which suggests that some eco-ethological mechanisms exist in their natural populations. A number of recent studies demonstrated that in Bulgaria A. flavicollis is more common than A. sylvaticus (Minkova and Popov, 2002; Popov, 2000, 2007, 2015). According to Peshev et al. (2004) the breeding of the yellow-necked mouse in Bulgaria occurs from March to the end of October. Responses to conspecific and heterospecific odours can provide insight into the socio- ecology of species even when little is known about the rela- tionships of the animals in nature. Odour communication is widespread in the animal world. With regard to small rodents olfactory cues are the most important cues used for conspecific, kin, sex, repro- ductive and social status recognition (Brown, 1979; Cox, 1984, 1989; Halpin, 1986; Hurst, 1989, 1990; Laukaitis et