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Nest Reuse by Eurasian Blackcap Sylvia atricapilla

Reusing old nests for breeding might provide birds with benefits such as saving the time and energy needed to build a new nest, or by decreasing the risk of predation while building a nest. Despite these benefits, many species use their nests only once. This study aimed to determine how frequently Eurasian Blackcaps Sylvia atricapilla, which build delicate open cup nests that are particularly susceptible to damage, might reuse their nest within a season and if extensive damage to a nest limited its reuse. I conducted the study in 2002–2008 in forests next to the city of Bydgoszcz in central Poland. I examined 479 Blackcap nests after the failure or success of the nest was known. Nests were classified as damaged or undamaged (73.7% of the sample). Only four nests were reused, representing 0.8% of all nests and 1.1% of the undamaged nests. The large number of undamaged but inactive nests indicated that the extent of damage was unlikely to be the reason that nests were rarely reused. The study also showed that Blackcaps rarely used material from an old nest to build a new nest.