Summary

From 2011-2015, we noted that 2.8 – 5.6% of male penduline tits in southwest Primorye, Russia, started the breeding season by repairing nest-baskets unfinished from the previous year. In 55% of these cases, occupation of old nests took place in the first days after males returned from their wintering grounds. After pair formation, both the male and the female finished building the nest together before occupying it. The presence of pendant, basket-like nests in the colony is explained by the polygynous nature of penduline tits. These nests, which sum 34.3% – 35.4% of all nests by the end of the breeding season, are built exclusively by unpaired males. Only 36.6% of the previous year’s nests were fully completed. The adaptive meaning of this behavior is discussed.