Relative breeding timing and reproductive success of a resident montane bird species
Data files
Jan 26, 2024 version files 370.45 KB
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mochage.csv
95.21 KB
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mochhigh.csv
71.94 KB
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mochlow.csv
99.64 KB
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README.md
4.38 KB
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Relative_Timing_Analysis.R
99.27 KB
Feb 27, 2025 version files 271.57 KB
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mochage.csv
95.21 KB
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mochhigh.csv
71.94 KB
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mochlow.csv
99.64 KB
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README.md
4.77 KB
Abstract
Wild populations appear to synchronize their reproductive phenology based on numerous environmental and ecological factors, yet there is still individual variation in the timing of reproduction within populations and such variation may be associated with fitness consequences. For example, many studies have documented a seasonal decline in reproductive fitness, but breeding timing may have varying consequences across different environments. Using 11 years of data, we investigated the relationship between relative breeding timing and reproductive success in resident mountain chickadees (Poecile gambeli) across two elevational bands in the Sierra Nevada mountains, USA. Chickadees that synchronized breeding with the majority of the population (“peak” of breeding) did not have the highest breeding success; instead, birds that bred early performed best at high elevation, while at low elevation early and peak nests performed similarly. At both elevations, late nests consistently performed the worst. Overall, breeding success decreased with increasing relative timing at both high and low elevations, but the relationship between breeding success and timing differed among years. Our results suggest that in mountain chickadees, earlier breeding is associated with higher reproductive success, especially at high elevations, while late breeding is consistently associated with lower reproductive success at both elevations.
https://doi.org/10.5061/dryad.bvq83bkh2
Authors: Lauren E. Whitenack, Carrie L. Branch, Benjamin R. Sonnenberg, Angela M. Pitera, Joseph F. Welklin, Virginia K. Heinen, Lauren M. Benedict, Vladimir V. Pravosudov
Contact Lauren Whitenack at lauren.whitenack@gmail.com with questions
Summary of data and code
This paper investigated the relationships between relative breeding timing and breeding success of mountain chickadees. The script includes code for all analyses and figures. The data used include reproductive data from high and low elevation sites and ages of individually-marked birds.
Please note that some cells in data files are blank. These cells have missing values - the data were not collected in these cases. Thus, blank values are equivalent to “NA”.
Data file: mochlow.csv
Summary: 11 years of breeding data from low elevation mountain chickadees at Sagehen Experimental Forest, CA, USA.
Each row contains data from a single nest associated with one season.
Column descriptions:
YEAR - Field season year
SEASON - Winter season preceding that year's breeding season
BOX - Nest box ID
ELEVATION - 'H' = high elevation; 'L' = low elevation
NEST.TYPE - all nests are initial nests ('INITIAL'), no renests or second nesting attempts included
NEST.ID - unique ID for each nest; IDs are not reused across years
M.RFID - RFID tag number of male parent
M.ID - Bird ID of male, corresponds to "BirdID" column of the mochage.csv file
M.TOIC - Male time of initial capture; date the male was first banded
F.RFID - RFID tag number of female parent
F.ID - Bird ID of female, corresponds to "BirdID" column of the mochage.csv file
F.TOIC - Female time of initial capture; date the female was first banded
FIRST.EGG - date of first egg laid; format = m/d/Y
J.FIRST.EGG - Julian date of first egg laid
CLUTCH - number of eggs at initiation of incubation
BROOD - number of eggs at day 16 in the nest
MEANMASS - mean nestling mass (g)
CV - coefficient of variation in nestling mass ((standard deviation÷mean)×100)
Data file: mochhigh.csv
Summary: 11 years of breeding data from high elevation mountain chickadees at Sagehen Experimental Forest, CA, USA.
Each row contains data from a single nest associated with one season.
Column descriptions:
YEAR - Field season year
SEASON - Winter season preceding that year's breeding season
BOX - Nest box ID
ELEVATION - 'H' = high elevation; 'L' = low elevation
NEST.TYPE - all nests are initial nests ('INITIAL'), no renests or second nesting attempts included
NEST.ID - unique ID for each nest; IDs are not reused across years
M.RFID - RFID tag number of male parent
M.ID - Bird ID of male, corresponds to "BirdID" column of the mochage.csv file
M.TOIC - Male time of initial capture; date the male was first banded
F.RFID - RFID tag number of female parent
F.ID - Bird ID of female, corresponds to "BirdID" column of the mochage.csv file
F.TOIC - Female time of initial capture; date the female was first banded
FIRST.EGG - date of first egg laid; format = m/d/Y
J.FIRST.EGG - Julian date of first egg laid
CLUTCH - number of eggs at initiation of incubation
BROOD - number of eggs at day 16 in the nest
MEANMASS - mean nestling mass (g)
CV - coefficient of variation in nestling mass ((standard deviation÷mean)×100)
Data file: mochage.csv
Summary: Ages of mountain chickadees by year at Sagehen Experimental Forest, CA, USA.
Each row contains data from a single bird associated with one season/year.
Column descriptions:
BirdID - Unique short ID for each individual bird that has been banded in this system
Season - Winter season preceding that year's breeding season
Active_breeding - Whether the bird was active during the breeding season following the winter season (Y or N)
Age - Numerical age (1-9) describing a bird's age in years
Age.confidence - Whether age is exact (bird banded as a juvenile) or minimum (bird banded as adult)
R Script: Relative_Timing_Analysis.R
All analyses were conducted in R version 4.1.3. The R script associated with this dataset is annotated and includes comparison of breeding timing ranges between elevations, categorical relative timing analysis, continuous relative timing analysis, and analysis comparing timing of breeding between parental ages. The script also contains code for all figures associated with this manuscript except for Figure A1 in the Appendix.
Change log
27 Feb 2025: Added analyses comparing lengths of breeding seasons between elevations and comparing timing of breeding across age classes.