DOI: 10.5061/dryad.ngf1vhj5n
title: Incubation period length varies with temperature, female age, and clutch size in Protonotaria citrea (Prothonotary Warblers)

description: 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.
description: # Incubation period length varies with temperature, female age, and clutch
 size in Protonotaria citrea (Prothonotary Warblers) Dataset DOI:
 [10.5061/dryad.ngf1vhj5n](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 (&gt; 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.