Breeding success and several breeding parameters were studied at 5 feral pigeon colonies. We found that density and the age of breeding pairs affect reproduction, with also the age of the nest significantly influencing reproductive indicators and success. Hatching, fledging and breeding success were higher in colonies with lower breeding pair densities. These indicators were also higher for experienced pairs compared to first time breeders. The number of nests in a pair’s territory had little effect on breeding performance. Among all the breeding parameters studied (timing of breeding, length of the breeding season, number of broods per year) only the latter was positively correlated with the density of birds. Breeding pairs had significantly more broods during a year in highly dense colonies compared with those of low density. The remaining factors studied were similar in all breeding colonies regardless of their density. Breeding parameters were primarily dependent on breeding pair age – experienced pairs began breeding earlier, ended later, conducted a longer breeding season and, as a result, produced more broods per year. The age of a nest also influenced the breeding season. Many factors were found to cause egg and nestling loss. Mechanical damage to eggs, eggs and nestlings falling out of nests, embryo death, jackdaw predation, competition among fledglings, and nestling disease were dependent on the level of pigeons’ reproductive activity, especially in overly dense colonies.