Chiffchaff (Phylloscopus collybita) Science Article 1
abstract
Two cases of year-to-year mate fidelity in Chiffchaff occurred in the subpopulation of 6 males and their females in a region of South Bohemia. The first nesting of both females failed in the first season. One of them was secondary female in the first season. Both pairs renested in a new territory in the second season. The nesting of both of them was successful in this season. This is probably the first record of remating between seasons in this species
Pavel Brandl, J. Orn. 137: 528-531