Chicks of cavity-nesting birds do not ‘exercise’ prior to fledging

Fledging represents a key life-history transition involving a rapid increase in workload associated with a rapid transition from sedentary nestling to volant, active fledgling. Here, we tested the idea that chicks might prepare for fledging through increased voluntary activity (‘exercise’) and whether this would impact somatic and physiological development. European starling (Sturnus vulgaris) chicks, in cavity nests, increased levels of putative exercise (wing flapping) and more general active behaviours (e.g., perching, standing) in the five days up to fledging. However, facultative mass loss and wing growth between days 15 – 20 were independent of time spent wing flapping, standing, or perching, and – counterintuitively – we found a weak negative relationship between hematocrit (a measure of aerobic capacity) and time spent wing flapping or standing. Thus, although exercise is commonly associated with an increase in hematocrit in other species, this does not appear to be a mechanism ..., , # Data from: Chicks of cavity-nesting birds do not ‘exercise’ prior to fledging

Dataset DOI: [10.5061/dryad.ffbg79d7m](https://doi.org/10.5061/dryad.ffbg79d7m)

## Description of the data and file structure

**Chicks of cavity-nesting birds do not ‘exercise’ prior to fledging**

Kate Earle ^1,2^, Josh Allen ^1,2^, Brett Hodinka ^1^, and Tony D Williams ^1^

**Note:** Within spreadsheets, \".\" values indicate either missing data (e.g., when chicks fledged early, before day 20, so day 20 blood samples and measurements could not be obtained, indicated by “earlyf” column) or b) where data were not collected in all years, e.g. behavioural data on maintenance, perching, sitting, standing and walking were only collected in 2023. These missing data are detailed for specific variables below:

**R code and data files**

A1) Activity_2021_22_220925_revision.R – R code for analysis of activity*chick age using 2021/22 data

A2) Activity_2021_22_220925_revision.csv – data for Activity 2021_22 analysi...,