Code and data to investigate the effects of parental pair-bond tenure (length of parental partnership) and parental pair-bond fidelity (whether pair-bond is maintained) on components of offspring fitness in the Seychelles warbler. Offspring fitness was characterised using measures of condition at the juvenile stage (telomere length, body mass, haematocrit) and long-term components (lifespan, lifetime reproductive success). Data was gathered from the long-term Seychelles warbler database and the pedigree available for the Seychelles warbler population on Cousin Island, Seychelles between 1997 to 2021 over all breeding seasons that were monitored. There are multiple datasets, all including a separate metadata file describing all variables used, with the same name as the file including "_metadata". All analyses and figures can be reproduced using the R-scripts using the datafiles supplied. Analyses were performed using R version 4.4.0.

R, 4.4.0

In many species, individuals form socially monogamous pair-bonds lasting multiple breeding seasons, or even whole lifetimes. Studies often suggest social monogamy to be adaptive, but this is usually quantified through the survival and annual reproductive success of the partners. However, beyond the number of offspring produced, parental partnerships may also affect their offspring’s phenotype, health, and ultimately fitness. Using multigenerational data on the Seychelles warbler (Acrocephalus sechellensis), we investigated the impact of parental pair-bond tenure (pair-bond duration) and pair-bond ending (pair-bond ended across breeding seasons) on offspring fitness components. First, we addressed juvenile-stage fitness components using indicators reflecting physiological state (haematocrit, telomere length, and body condition). Second, we assessed long-term fitness components using offspring lifespan and lifetime reproductive success (LRS). We found no consistent evidence of pair-bond tenure or pair-bond ending effects on short-term (telomere length, haematocrit, body condition) or long-term (lifespan, LRS) fitness components. To our knowledge, this is the first study quantifying long-term parental effects of pair-bond tenure and pair-bond ending on offspring fitness components in wild populations. This work provides insights into the lack of intergenerational implications of long-term socially monogamous partnerships.