ABSTRACTSmall, isolated and fragmented bird populations are more vulnerable to extinction and studies have shown that they can have a high proportion of unpaired males. Female-biased natal dispersal could be an explanation of the low male pairing success. Indirect evidence has shown that such an effect operates between populations with different degree of isolation. How isolation affects male pairing success within a population is not well known, and in this study I examinedisolation within the population of the endangered ortolan bunting (Emberiza hortulana), both between patches and between males in relation to pairing success. The aim was to test thehypothesis presented by Dale, that pairing success within small and fragmented populations may also be affected by degree of isolation. The ortolan bunting population has a skewed male-biasedsex ratio, with a high number of unpaired males. Other factors that could have an effect on pairing success, like habitat and territory quality, patch size and patch population size were alsoexamined. I found no effect of isolation on male pairing success within the population, neither on a territorial level nor on patch level. Patch size and patch population size did not have an effecton male pairing success, but habitat in territory showed a highly negative effect on pairing success within the habitat category recently cleared ground. I found no effect of isolation whenincluding habitat in the main analysis. Even though Dales hypothesis was not confirmed in this study, there is indirect evidence from the last years research on the species, that it could operateon a larger scale within the population.