Twelve polymorphic microsatellite loci were characterized in order to investigate an extreme case of microgeographical variation in an island-dwelling passerine (Zosterops borbonicus). Variation was examined in two distinct natural populations of 27 individuals each. The loci displayed 5–20 alleles, with observed heterozygosities ranging between 0.33 and 0.93. All but one loci (Z16) conformed to Hardy–Weinberg equilibrium. None of the pairwise comparisons among loci showed significant linkage disequilibrium after sequential Bonferonni correction. Successful cross-species amplification in additional Zosterops species and other passerines suggests their broad applicability.