Incubation period length varies with temperature, female age, and clutch size in Protonotaria citrea (Prothonotary Warblers)
Data files
Jul 14, 2025 version files 129.29 KB
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Incubation_Length_Analysis.Rmd
14.41 KB
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Incubation_Length_Dataset_Metadata.xlsx
10.22 KB
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Incubation_Length_Dataset.csv
101.44 KB
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README.md
3.22 KB
Abstract
The length of the incubation period is determined by the development rate of embryos, which is dependent on thermal stability provided by environmental conditions and parental incubation behavior. With climate change, many bird species are advancing their breeding earlier in the season. This exposes broods and parents to more variable temperatures and inclement weather conditions. Assessing how the length of the incubation period varies with weather conditions is important for understanding potential consequences of phenological advancements with climate change, such as higher offspring mortality-risk and parental energetic demands. This study examined the length of the incubation period in response to weather conditions (i.e., temperature and precipitation), female age, clutch size, and timing of breeding (early vs. late season) in a population of nest-box breeding Protonotaria citrea (Prothonotary Warblers). Across 1,036 clutches spanning 22 years, we found the incubation period to range between 10 and 16 days. Results indicated that low temperatures, young mothers, and small clutch sizes contributed to longer incubation periods. Precipitation did not affect incubation period length. Early and late season clutches did not differ when accounting for temperature, female age, and clutch size. We also found minimum daily temperatures during the incubation period to be highly correlated with the overall variation in temperatures. These results indicate that advancements in breeding expose clutches to colder and more variable temperatures, resulting in longer incubation periods, but this effect is likely mitigated by larger clutches and a higher proportion of older females in the early season.
Dataset DOI: 10.5061/dryad.ngf1vhj5n
Description of the data and file structure
Long-term Prothonotary Warbler (Protonotaria citrea) nest data was collected from 1999 to 2023 at three sites along the James River in Virginia, USA. We assessed the abiotic and biotic factors that influenced the length of incubation period across 1,036 clutches spanning 22 years.
Files and variables
Files Include:
Incubation_Length_Dataset.csv, Incubation_Length_Dataset_Metadata.xlsx, and Incubation_Length_Analysis.Rmd
Descriptions:
Incubation_Length_Dataset.csv
This dataset represents the raw data used in our analysis. Each row represents a unique clutch monitored in our study system. Each column is a variable used in our analysis.
Variables
- Sample: Sample Number
- Year: The year documented clutch took place (1999-2023).
- BandNumber: USFWS band number. Unique numbers represent individual females.
- IncLength: Length of the incubation period (in days). Calculated by subtracting incubation start date (i.e., day final egg was laid) from the hatch date.
- mean_min_temps: Average minimum daily temperatures (Celsius) during the first 10 days of the incubation period.
- mean_max_temps: Average maximum daily temperatures (Celsius) during the first 10 days of the incubation period.
- CVmin: The Coefficient of Variation of minimum daily temperatures during the first 10 days of the incubation period.
- CVmax: The Coefficient of Variation of maximum daily temperatures during the first 10 days of the incubation period.
- CVminmax: The Coefficient of Variation of minimum and maximum daily temperatures during the first 10 days of the incubation period.
- total_range: The absolute temperature range (Celsius) during the first 10 days of the incubation period (i.e., highest max - lowest min)
- rain_cuml: The cumulative rainfall (millimeters) during the first 10 days of the incubation period.
- rain_days_P: The proportion of days that experienced rain (> 0 mm) during the first 10 days of the incubation period.
- F_age_yrs: Age of incubating female as her number of years of breeding experience (first year breeder = 1)
- F_age_SYvASY: Age of incubating female as second-year (i.e., first year breeder) or after-second-year. Identified by female plumage.
- clutch_size: Number of eggs in clutch.
- seasonality: Whether clutch was initiated in the early (i.e., on or before June 1) or late breeding season.
Incubation_Length_Dataset_Metadata.xlsx
This file provides descriptions and sources for each of our variables (as described above).
Code/software
Incubation_Length_Analysis.Rmd
This file, demonstrating the code used for our analysis, was created using R version 4.2.1. Required packages include "dplyr", tidry", "lme4", "AICcmodavg", "ggplot2", and "performance". Annotations and descriptions are provided throughout the file.
Access information
Data was derived from the following sources:
- National Oceanic and Atmospheric Administration (NOAA) online climate database.