Data from: Phenological mismatch and ontogenetic diet shifts interactively affect offspring condition in a passerine

Climate change may cause phenological asynchrony between trophic levels, which can lead to mismatched reproduction in animals. Although indirect effects of mismatch on fitness are well described, direct effects on parental prey choice are not. Moreover, direct effects of prey variation on offspring condition throughout their early development are understudied.
Here, we used camera trap data collected over 2 years to study the effects of trophic mismatch and nestling age on prey choice in pied flycatchers (Ficedula hypoleuca). Furthermore, we studied the effect of mismatch and variation in nestling diet on offspring condition.
Both experimentally induced and natural mismatches with the caterpillar peak negatively affected absolute and relative numbers of caterpillars and offspring condition (mass, tarsus and wing length) and positively affected absolute and relative numbers of flying insects in the nestling diet. Feeding more flying insects was negatively correlated with nestling day 12 mass.
Both descriptive and experimental data showed preferential feeding of spiders when nestlings were <7 days old. Receiving more spiders during this phase was positively correlated with tarsus growth.
These results highlight the need for a more inclusive framework to study phenological mismatch in nature. The general focus on only one prey type, the rarity of studies that measure environmental abundance of prey, and the lack of timing experiments in dietary studies currently hamper understanding of the actual trophic interactions that affect fitness under climate change.

The data package contains five sets:
- Contains the R script that uses the data file 1213all.csv to analyze dietary variation and make the graphs.
- Principal file containing all the prey data
- R script to analyze effect of diet on components of fitness. Reads into the data file fitndiet1213.csv and feeding1213.csv
- Contains the feeding rates of different prey types across age classes
- Contains measures of offspring condition and feeding rates