We measured differences in behavioural responses of territorial Tawny Owls to four stimuli: (i) hootings of a neighbouring conspecific male, (ii) hootings of a stranger conspecific male, (iii) calls of a Long-eared Owl male and (iv) barking of a Roe Deer Capreolus capreolus (L.) male (as a control). In the breeding season, responses to the playbacks of Tawny Owls' (both stranger and neighbour) and Long-eared Owls' vocalisations did not differ from one another, but they were all different (i.e. stronger) in the responses to the control stimulus (iv). Outside the breeding season, responses to the hootings of Tawny Owls (b0th stranger and neighbour) differed from responses to the other two stimuli (with no differences within the pairs). This suggests that, while conspecifics (both neighbours and strangers) are 'enemies' of Tawny Owls throughout the year, Long-eared Owls belong to that category only in the breeding season, when they establish territories and become competitors. On the other hand, Long-eared Owls in our study area are extremely reluctant to respond even to playbacks of conspecifics. Both facts seem to support Murray's hypothesis about non-adaptive interspecific territorialism.