The latitudinal increase in extra-pair paternity (EPP) rates in birds suggests broad selective benefits to low EPP rates in the tropics. However, we have few EPP data from tropical birds, particularly from species with close relatives at high latitudes. Here, we report EPP rates in two resident equatorial populations of rufous-collared sparrow Zonotrichia capensis, a genus well-represented at high latitudes. We found 64% and 60% of broods contained extra-pair offspring, and 42% and 52% of all young were extra-pair. EPP rates were similar in these populations, despite clear differences in elevation, temperature, rainfall, and breeding season length. These findings provide evidence that EPP rates in tropical birds can be as high as those observed in temperate birds, and suggest that the selective pressures acting on EPP rates vary markedly across tropical birds.