Oscine passerine birds learn their songs principally through cultural transmission. However, habitat fragmentation might induce cultural variation in song, leading to restrictions in the transmission of cultural information. In this study, we aim to evaluate individual responsiveness to conspecific vocalisations within and between two nearby bird populations to assess within-species behavioural changes with distance. To do so, we used song playbacks of'Elepaio Chasiempis sandwichensis in a fragmented landscape on the north-east slope of Mauna Loa Volcano (Hawaii Island, USA). We evaluated the response of'Elepaio males to songs recorded in their own populations and to those recorded in another population. We also compared vocalisations between both populations to assess acoustic differentiation. Our results indicate behavioural divergence in song responsiveness over a small spatial scale for this species as well as significant differences in acoustic traits. However, contrary to what was expected,'Elepaio individuals from both populations did not vary in their response pattern to songs depending on their origin. This suggests that acoustic differentiation may not be strong enough to drive behavioural divergence in response of'Elepaio individuals despite the existence of differences in the acoustic traits between both populations.—Oñate-Casado, J., Sebastián-González, E. & Hart, P.J. (2020). Response of male Hawaii Elepaio Chasiempis sandwichensis to conspecific songs: a small-scale playback study. Ardeola, 67: 387-400.