Abstract. We studied song dialects of the Rufous-collared Sparrow (Zonotrichia capensis) in espinal woodland and steppe surrounding Guatraché Lake in Argentina. We recorded 150 individuals and analyzed 14 quantitative song variables. There were significant differences between habitats in song temporal structure. In particular, the internote interval of trills was shorter in the closed compared to the open habitat. This pattern is the reverse of what is usually found in this species, although it has previously been detected in another area of the region in which this study was conducted. This region is characterized by strong winds, which could be related to the reversed pattern found. Song frequencies were lower in the closed woodland habitat than in the open steppe, which also contrasts with the pattern usually found in this species. We also recorded and analyzed the songs in a portion of the area in which the woodland was converted into grassland during the last century. The temporal structure of songs in the converted area was intermediate between song structures in the original habitats and frequencies were lower in the converted area than in both original habitats. Song structure appears to have changed after habitat conversion, but this cannot be confirmed with the data at hand because of the lack of recordings obtained before habitat change.