Dataset DOI: 10.5061/dryad.dz08kpsbq

Description of the data and file structure

The data files contain data collected by surveying three sites within the city limits of Lexington, KY, over the breeding seasons of 2023 and 2024 for nests of Northern cardinal (Cardinalis cardinalis), a species of least concern. The three sites were the University of Kentucky’s Ecological Research and Education Center (EREC; 38.080597, -84.474786), the University of Kentucky’s 40.5 ha Arboretum and Botanical Gardens (Arboretum; 38.015189, -84.503797), and the University of Kentucky’s main campus (Campus, 38.036010, -84.504356). The data come from the following nests from discovery to failure or fledging, weighing eggs upon initial discovery, and weighing nestlings every visit.

Files and variables

File: Nestobs.csv

Description: This file contains entries for each visit to each nest, indicating the order, the fate of the nest on that visit, the days between each visit, and dates. These data are suitable for analyzing daily survival rates. Blank cells indicate missing data.

Variables

• Nest: A within-year, within-site ID for each nest.
• NestID: A unique identity for each nest in each year by each site. 
• Site: A code for the three sites survey (EREC = Ecological Research and Education Center, Arb = University of Kentucky Arboretum, Campus = University of Kentucky main campus). 
• Year: Year of observation, either 2023 or 2024
• Date: Calendar date of observation
• Phase: Stage of nesting, either Inc = with eggs or Nestlings. 
• Visit: The visit order to the nest, where 1 = the visit when the nest was first found. 
• Fate: Whether nest still had eggs or young (1) or was empty (0). 
• Interval: Order of visits included in data 
• Expose: Number of days since previous visit.
• trials: Index indicating each visit counted as 1 trial
• Firstdate: Date when nest received first egg, coded as Julian date
• FirstdateMC: Mean-centered version of Firstdate. 

File: Combined_Eggs.csv

Description: File containing data on each egg found and weighed during the study across 2 seasons. Missing data are indicated by an NA. 

Variables

• Site: Location where nest was found  (EREC = Ecological Research and Education Center, Arb = University of Kentucky Arboretum, Campus = University of Kentucky main campus). 
• Year: Year of study (2023 or 2024)
• Nest: Within the year code for the nest.
• NestID: Unique ID for each nest comprised of Nest plus Year. 
• EggID: Unique ID for each egg across all nests in all years.
• Date: Date of measurement. 
• JulianDate: Date converted to Julian Date.
• Time: Time data was collected (24 h clock). NA = Time was not recorded.
• Contents: Within nest code for each egg.
• Species: Whether a cardinal (CARD) or brown-headed cowbird (COWBIRD) egg.
• Weight: Mass in grams of the focal egg.
• FirstEggDate: Date when the first egg was laid. NA = Either no egg was ever laid or the nest of eggs failed, and so it could not be known.
• JulianFED: Julian date version of first egg date. NA = No date of first egg was available. 
• Use: Whether observation should be used, given additional information collected later (such as if the egg was abandoned much earlier). N = Do not use. Y = Use.
• EggAge: Age in days since date of first egg of egg when measured. NA = No egg laid, so not applicable, or it could not be determined.
• HatchDate: Date eggs hatched. NA = Either nest had no eggs or none hatched. 

File: Combined_Nestlings.csv

Description: File of individual observations of each nestling in the two-year survey at three sites. 

Variables

• Site: Location where nest was found  (EREC = Ecological Research and Education Center, Arb = University of Kentucky Arboretum, Campus = University of Kentucky main campus). 
• Year: Year of study (2023 or 2024)
• NestlingID: Unique identity code for each nestling across years, sites, and nests. 
• Nest: Code for each nest within a year. 
• NestID: Unique code for nest across sites and years. 
• Date: Date of measurement
• Time: Time of measurement (24 h clock). NA = Time was not recorded.
• Contents: Within-nest identity of nestling. 
• Code: Label of how nestlings were marked for individual recognition if there was more than one (2024 only).
• Species: Whether nestling was cardinal (CARD) or cowbird (COWBIRD). 
• Weight: Mass in grams of nestling. 
• Age_estimate: Estimate of the age since hatching based on appearance. 
• Accurate: Code for whether age estimate was accurate (Y) or not (N) based on if neslting appeared less than 2 days old. 
• EstimatedAgeAtFirstMeasure: Age_estimate on first measure.
• HoursBetweenMeasures: Time in hours since the previous measure. 
• HoursSinceFirstMeasure: Time in houses since the first measure.
• WeightChange: Change in mass since previous measure.
• WeightChangeFirst: Change in mass since first measure.
• BroodSize: Number of nestlings (both species) in nest at time of measurement. 
• HatchDate: Date majority of nestlings hatched. 
• JulianHatchDate: Date majority of nestlings hatched converted to Julian scale. 
• NumCow: Number of cowbird nestlings in nest at time of measurement. 

File: Combined_Nests.csv

Description: This file contains a single summary record for each nest found at all three sites in each year. These data are suitable for analyzing clutch size and overall hatching or fledging success. 

Variables

• Number: Nest id indicating site but not year.
• Year: Year of study (2023 or 2024). 
• Site: Location where nest was found  (EREC = Ecological Research and Education Center, Arb = University of Kentucky Arboretum, Campus = University of Kentucky main campus). 
• Date found: Date when nest was found
• Height: Estimated height of nest in feet. 
• Nest plant: Type of plant, common name of group. NA = Unknown or not recorded.
• Fate: Fate of nest (Fledged = empty after nestlings 8+ days were seen, Predated = empty before fledging could occur, Abandoned = at least one egg found but never incubated, Never active= nest start or shell found but never seen with eggs. 
• NumEggs: Eggs present when found. NA = Not applicable as no eggs seen
• NumEggsHatched: Number of hatchlings. NA = Not applicable as no eggs seen
• CardEggs: Number of eggs seen that were cardinal. NA = Not applicable as no eggs seen
• CardEggsHatched: Number of cardinal eggs that hatched. NA = Not applicable as no eggs seen
• Proportion of Cardinal Clutch Hatched: Proportion of cardinal eggs that hatched. NA = Not applicable as no eggs seen.
• Proportion of Total Clutch Hatched: Proportion of cardinal plus cowbird eggs that hatched. NA = Not applicable as no eggs seen.
• Cardinal Brood Size: Number of cardinal nestlings. NA = Not applicable as no eggs seen.
• Total Brood Size: Total number of nestlings (cardinal plus cowbird). NA = Not applicable as no eggs seen.
• Cardinals Fledged: Number of cardinal nestlings that were present until 8 days of age or more. NA = Not applicable as no eggs seen.
• Total Fledged: Number of cardinal and cowbird eggs that were present until 8 days or more. NA = Not applicable as no eggs seen or hatched.
• DayDiscFailed: Date of visit in which nest was discovered having failed. NA = Not applicable if no eggs seen.
• FED: Date first egg was laid (calculated). NA = Not applicable as no eggs seen.
• TrueFED: Code for if first egg date was calculated from either see eggs laid between visits or eggs hatched so first egg date could be calculated (Y). Nests that were found after clutch completion and failed before hatching = N. NA = Not applicable as no eggs seen.
• JulianFED: FED on Julian scale. NA = Not applicable as no eggs seen.
• Parasitized: Y = at least one cowbird egg or nestling present, N = all cardinal eggs or nestlings, NA = Not applicable if nest never had any contents. 

Code/software

Any program that reads .csv files.

Access information

Other publicly accessible locations of the data:

• None

Data was derived from the following sources:

• Not applicable