Ecological drivers and fitness consequences of incubation period in <i>Ficedula albicollis</i> (Collared Flycatcher): Insights from a long-term data set

Abstract Using a 37-year dataset of Ficedula albicollis (Collared Flycatcher) we examined how incubation duration is influenced by environmental conditions and female characteristics. In our study, we clearly demonstrated that the length of the incubation period exhibits variability and may be subject to selection. Our findings indicate that the duration of the incubation period tended to affect hatching success but played a more substantial role in recruitment, which is a key indicator of fitness. We found that incubation duration is significantly affected by laying date, clutch size, female body condition, and ambient temperature, including its variability. Interestingly, both low and high ambient temperatures are linked to shorter incubation periods. In turn, an increase in temperature variability is associated with shortening incubation periods. Further research is needed to explore the long-term impacts of these incubation strategies on population viability, particularly in the face of increasing climate variability.