Stable immune function during moult regardless of age-specific moulting strategy in a European passerine

This file contains data on moulting status, moult progression and baseline innate immune function (bacterial-killing ability, lysis, agglutination, haptoglobin concentration) in adult and juvenile blackbirds captured in Lund, southern Sweden, in 2019–2020 (Aug–Oct).
Moult, the regular replacement of feathers, is a resource-intensive avian annual cycle stage. Resource allocation to support feather regrowth may require downregulation of other physiological processes, such as immune function, which is critical for preventing disease-related mortality. At the same time, the emergence of new feathers may increase the risk of skin injury and infection, potentially requiring sustained or enhanced immunocompetence during this period. While previous studies have compared immune function between moulting and non-moulting individuals, it remains unclear how immune function changes throughout moult. Moreover, little is known about how these dynamics manifest in age-specific moulting strategies, suc..., , # Stable immune function during moult regardless of age-specific moulting strategy in a European passerine

Dataset DOI: [10.5061/dryad.612jm64kb](https://doi.org/10.5061/dryad.612jm64kb)

## Description of the data and file structure

We recorded moult status (not-yet moulting, moulting, completed moult) and the progression of primary wing feather moult in adult blackbirds. We also assessed the extent of body feather replacement in juvenile blackbirds. In addition, we took a small blood sample from each bird to measure four parameters of baseline innate immune function (bacterial-killing ability, lysis, agglutination, haptoglobin concentration). 

### Files and variables

#### File: Moult_immune_function_data.csv

**Description:** 

##### Variables

* ID: individual metal ring number
* age: age class (juv = juvenile (first-year); ad = adult (second-year or older)
* sex: sex (determined in the field (for adults) or in the lab (for juveniles, using molecular sexing techniques))
* year: y...,