<p>Nest building can be time and energetically costly. For this reason, the construction of multiple non-breeding nests by some birds has been of scientific interest for decades, especially when it is associated with complex social interactions. However, neither the variety of study systems nor the potential hypotheses have been totally exploited. Here, we reveal that male chestnut-capped blackbirds <i>Chrysomus ruficapillus</i> are among the birds constructing the highest numbers of nests, most of which are never chosen by females for breeding. Significant correlation between the number of nests constructed by males throughout the breeding season and the number of social clutches, as well as the observation of males having up to four active nests at a time provided support to a polygyny strategy. We failed to show that the number of constructed nests is a signal that can be assessed by females because females chose nests following a pattern that did not deviate from random. In terms of sexual conflicts, because the numbers of non-breeding nests did not provide increased survival for breeding nests, the reduced female investment in nest construction and the increased possibility of mating with the higher quality males just because of random nest choice are variables likely making of this an evolutionarily stable reproductive strategy.</p>