Data and code from: Fitness and flexibility of metabolic phenotypes in a temperate resident bird
Data files
Sep 11, 2026 version files 143.50 KB
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01_correlations.csv
5.44 KB
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02_repeats.csv
1.91 KB
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03_survival.csv
5.30 KB
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04_breeding.csv
4.56 KB
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05_nestlings.csv
27.06 KB
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06_springMMR.csv
3.30 KB
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07_springNestlings.csv
40.83 KB
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Func_ecol_2026_script.R
46.53 KB
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README.md
8.56 KB
Abstract
Resident songbirds in seasonal environments are adapted to fluctuating conditions and show marked phenotypic flexibility of metabolic rates. However, the potential strength and direction of selection for metabolic phenotypes may depend on the context of the seasonal and environmental conditions, which standardized metabolic rate is measured, and which life-history traits (i.e., survival and reproduction) are considered.
To investigate how metabolic rates co-vary and to characterize individuals by a metabolic phenotype, we measured three different metabolic rates that we expected to be important for fitness – the maintenance metabolic rate (BMR), maximum cold-induced metabolic rate (Msum) and maximum exercise-induced metabolic rate (MMR) – in a population of blue tits (Cyanistes caeruleus) in southern Sweden. We then monitored different predictors of fitness for those individuals: apparent survival and breeding success.
All three metabolic rates were significantly, positively related, and the relationship between Msum and MMR was positive independent of body mass. MMR was repeatable between seasons, suggesting consistent individual differences consistent with metabolic phenotypes. From breeding data, individuals with higher metabolic rates in spring were marginally more likely to return to breed the following year. However, high metabolic rates were associated with somewhat lower reproductive success.
This study contributes to our understanding of how individual phenotypic variation and flexibility manifests in a population of temperate resident birds. While clear associations between metabolic rates and fitness remain elusive, our results provide tentative support for context-dependent selection on metabolic rates.
Dataset DOI: 10.5061/dryad.gxd25481n
Description of the data and file structure
To investigate how metabolic rates co-vary and to characterize individuals by a metabolic phenotype, we measured three different metabolic rates that we expected to be important for fitness – the maintenance metabolic rate (BMR), maximum cold-induced metabolic rate (Msum) and maximum exercise-induced metabolic rate (MMR) – in a population of blue tits (Cyanistes caeruleus) in southern Sweden. We then monitored different predictors of fitness, the apparent survival and breeding success (laying date and clutch size), of those individuals.
All three metabolic rates were significantly, positively related, and the relationship between Msum and MMR was positive independent of body mass. MMR was highly repeatable between seasons, suggesting that individual differences are consistent across seasons. We did not find a link between metabolic rates and apparent survival between capture in February and re-sighting during the breeding season in April - June. From breeding data, we found weak but consistent indications that having higher metabolic rates in winter may be negatively related to reproductive success in spring.
Files and variables
File: 01_correlations.csv
Description: Data used in reduced major axis regressions (RMA). NA values indicate that the data was not collected. This is because of equipment malfunction or because some birds were released early if they were not eating the provided food.
Variables
- ringnr: Bird individual ID
- age: Age determined from plumage characteristics (2k = 2nd calendar year, 3k+ = 3rd calendar year or later)
- sex: Sex determined from plumage characteristics (M = male, F = female)
- MMR: Maximum exercise-induced metabolic rate (W)
- Msum: Maximum cold-induced metabolic rate (W)
- BMR: Maintenance metabolic rate of birds measured overnight in post-absorptive birds in thermoneutrality (W)
- mass_MMR: Body mass measured immediately before MMR measurements (g)
- residuals_MMR: MMR residuals of linear regression with body mass
- mass_Msum: Body mass measured immediately before Msum measurements (g)
- residuals_Msum: Msum residuals of linear regression with body mass
- mass_out_BMR: Body mass measured immediately after BMR measurements (g)
- residuals_BMR: BMR residuals of linear regression with body mass
File: 02_repeats.csv
Description: Data used in the analysis of repeatability of MMR between seasons
Variables
- ringnr: Bird individual ID
- MMR: Maximum exercise-induced metabolic rate (W)
- mass: Body mass measured immediately before MMR measurements (g)
- residuals_MMR: MMR residuals of linear regression with body mass
- year: Year and season when measurement was taken
- season: Season when measurement was taken (winter or spring)
File: 03_survival.csv
Description: Data used in analysis of apparent survival of birds measured in winter
Variables
- ringnr: Bird individual ID
- age: Age determined from plumage characteristics (2k = 2nd calendar year, 3k+ = 3rd calendar year or later)
- sex: Sex determined from plumage characteristics (M = male, F = female)
- BMR: Maintenance metabolic rate of birds measured overnight in post-absorptive birds in thermoneutrality (W)
- Msum: Maximum cold-induced metabolic rate (W)
- MMR: Maximum exercise-induced metabolic rate (W)
- mass_out_BMR: Body mass measured immediately after BMR measurements (g)
- BMR_c: Scaled and centered maintenance metabolic rate of birds measured overnight in post-absorptive birds in thermoneutrality
- Msum_c: Scaled and centered maximum cold-induced metabolic rate
- MMR_c: Scaled and centered maximum exercise-induced metabolic rate
- mass_out_BMR_c: Scaled and centered body mass measured immediately after BMR measurements
- resight: Binary variable indicating if the bird was resighted in the following spring or not (0 = no, 1 = yes)
- mr_date: Date of metabolic measurements in winter
- mr_date_c: Scaled and centered date of metabolic measurements in winter
File: 04_breeding.csv
Description: Data used in analysis of laying date and clutch size of birds measured in winter.
Variables
- Nestbox: Nest ID
- year: Year when breeding data was collected
- ringnr: Bird individual ID
- Age: Age determined from plumage characteristics (2k = 2nd calendar year, 3k+ = 3rd calendar year or later)
- sex: Sex determined from plumage characteristics (M = male, F = female)
- BMR: Maintenance metabolic rate of birds measured overnight in post-absorptive birds in thermoneutrality (W)
- Msum: Maximum cold-induced metabolic rate (W)
- MMR: Maximum exercise-induced metabolic rate (W)
- mass_out_BMR: Body mass measured immediately after BMR measurements (g)
- BMR_c: Scaled and centered maintenance metabolic rate of birds measured overnight in post-absorptive birds in thermoneutrality
- MMR_c: Scaled and centered maximum exercise-induced metabolic rate
- Msum_c: Scaled and centered maximum cold-induced metabolic rate
- mass_out_BMR_c: Scaled and centered body mass measured immediately after BMR measurements
- laying_date: Date when the first egg was layed (mm/dd/yy)
- laying_date_j: Julian date when the first egg was layed
- clutch_size: Number of eggs in the clutch
- mass_spring: Adult body mass when captured in spring (g)
File: 05_nestlings.csv
Description: Data used in analysis of nestling mass for birds measured in winter
Variables
- Nestbox: Nest ID
- year: Year when breeding data was collected
- ringnr: Bird individual ID
- Age: Age of parent determined from plumage characteristics (2k = 2nd calendar year, 3k+ = 3rd calendar year or later)
- sex: Sex of parent determined from plumage characteristics (M = male, F = female)
- BMR: Maintenance metabolic rate of parent measured overnight in post-absorptive birds in thermoneutrality (W)
- Msum: Maximum cold-induced metabolic rate of parent (W)
- MMR: Maximum exercise-induced metabolic rate of parent (W)
- mass_out_BMR: Body mass measured immediately after BMR measurements (g)
- BMR_c: Scaled and centered maintenance metabolic rate of birds measured overnight in post-absorptive birds in thermoneutrality
- MMR_c: Scaled and centered maximum exercise-induced metabolic rate
- Msum_c: Scaled and centered maximum cold-induced metabolic rate
- mass_out_BMR_c: Scaled and centered body mass measured immediately after BMR
- clutch_size: Number of eggs in the clutch
- mass_spring: Mass of parent when captured in spring (g)
- ID: Nestling ID
- Ringing.date: Date of nestling measurements
- n.mass: Nestling body mass (g)
File: 06_springMMR.csv
Description: Data used in analyses of male birds measured in spring
Variables
- year: Year when breeding data was collected
- ringnr: Bird individual ID
- age: Age determined from plumage characteristics (2k = 2nd calendar year, 3k+ = 3rd calendar year or later)
- MMR: Maximum exercise-induced metabolic rate (W)
- MMR_c: Scaled and centered maximum exercise-induced metabolic rate
- mass: Body mass measured immediately before MMR measurements (g)
- mass_c: Scaled and centered body mass measured immediately before MMR measurements
- aprild: Date when the first egg was layed in April days (days after March 31)
- clutch_size: Number of eggs in the clutch
- resight: Binary variable indicating if the bird was resighted in the following spring or not (0 = no, 1 = yes)
File: 07_springNestlings.csv
Description: Data used in analysis of nestling mass for birds measured in spring
Variables
- Nestbox: Nest ID
- year: Year when breeding data was collected
- ringnr: Bird individual ID
- age: Age determined from plumage characteristics (2k = 2nd calendar year, 3k+ = 3rd calendar year or later)
- MMR: Maximum exercise-induced metabolic rate of parent (W)
- MMR_c: Scaled and centered maximum exercise-induced metabolic rate of parent
- mass: Body mass of parent measured immediately before MMR measurements (g)
- mass_c: Scaled and centered body mass of parent measured immediately before MMR measurements
- ID: Nestling ID
- Ringing.date: Date of nestling measurements
- n.mass: Nestling body mass (g)
File: Func_ecol_2026_script.R
Description: Script for reproducing all analyses, tables and figures in the paper and electronic supplementary material