Data from: Long-term apparent survival of capercaillie (Tetrao urogallus) translocated from Sweden to East Germany
Data files
May 23, 2026 version files 46.69 KB
-
caper_data.csv
41.20 KB
-
README.md
5.49 KB
Abstract
The dataset contains individual-based demographic and monitoring data from a long-term reintroduction program of the Western Capercaillie in Lower Lusatia, eastern Germany, conducted between 2012 and 2024. The dataset includes records of wild-caught adult capercaillie translocated from Sweden as well as individuals reared under the mother-assisted “born to be free” method using eggs laid by transported females and subsequently released into restored forest habitats in Germany. For each individual, the dataset provides a unique identifier, origin, sex, release year and release date, body mass at capture, telemetry status, mortality information (if known), and annual encounter histories spanning 2012–2024. Annual binary encounter variables indicate whether an individual was genetically or otherwise detected in a given year and were used to construct capture–mark–recapture histories for survival analyses. A subset of individuals was additionally monitored using radio or GPS telemetry, allowing comparisons between genetic and telemetry-based estimates of apparent survival. The dataset supports analyses of long-term survival, sex-specific demography, and comparisons between release strategies and early-life histories in reintroduced populations. It may further be reused for methodological studies on non-invasive genetic monitoring, capture–mark–recapture modelling, conservation translocations, and population viability assessments of grouse and other birds. No sensitive location data of active breeding sites are included. Individual identifiers were anonymized and reformatted for publication. The dataset is associated with a manuscript evaluating long-term demographic performance of translocated capercaillie, including comparisons between wild-caught adults and individuals reared under the “born to be free” method, using genetic capture–mark–recapture and telemetry data.
Dataset DOI: 10.5061/dryad.73n5tb3cn
Description of the data and file structure
This dataset was collected within a long-term reintroduction program of the Western Capercaillie in Lower Lusatia, eastern Germany, between 2012 and 2024. The program aimed to establish a self-sustaining population through translocation of wild-caught individuals from Sweden and release of juveniles reared under the mother-assisted “born to be free” method.
Adult capercaillies were captured in the Swedish provinces of Dalarna, Jämtland, and Västerbotten either at leks using mist nets or along forest roads using dip nets. Captured individuals were ringed, sexed, weighed, sampled for genetic analyses, and transported to the release area in Germany. A subset of transported females laid eggs during transport or shortly after release; these eggs were used for chick rearing under the “born to be free” method at Park Dzikich Zwierząt w Kadzidłowie, Poland.
Between 2012 and 2013, a subset of released birds was equipped with GPS and accelerometer transmitters to enable radio-telemetry monitoring. Telemetry data were used to assess movement, survival, and mortality events. Monitoring intensity differed between project phases, with intensive telemetry during the pilot phase (2012–2014) and increased emphasis on non-invasive genetic monitoring during the implementation phase (2015–2024).
Genetic monitoring was conducted annually between June and August using non-invasive feather sampling. Feathers were collected at dust-bathing sites and other locations frequented by capercaillie. Individual identification was performed using mitochondrial sequencing and microsatellite genotyping. Annual encounter histories derived from genetic detections and telemetry records were used for analyses of apparent survival, sex-specific demography, and translocation success.
Files and variables
File: caper_data.csv
Description: This file contains individual-based demographic and monitoring data for translocated Western Capercaillie released in Lower Lusatia, Germany, between 2012 and 2024. The dataset includes information on origin, sex, release year, body mass at capture, telemetry status, mortality records, and annual encounter histories derived from genetic monitoring and telemetry.
Annual encounter history variables (2012–2024) are binary detection indicators used for capture–mark–recapture analyses of apparent survival and site fidelity.
Missing values are indicated as NA.
Variables
- ID: Unique anonymized identifier assigned to each individual.
- origin: Origin of the translocated individual.
- Codes:
- SE = Sweden
- btbf = "born to be free" - method
- Codes:
- sex: Sex of the individual.
- Values:
- male
- female
- Values:
- release: Year of release in Germany.
- Unit: calendar year
- rel_date: Date of release.
- Format: YYYY-MM-DD
- catch_weight: Body mass recorded at capture.
- Unit: grams (g)
- mortality: Date of confirmed mortality, if known.
- Format: YYYY-MM-DD
- Missing values (NA) indicate that mortality was not confirmed during the study period.
- mortyear: Year of confirmed mortality, if known.
- Unit: calendar year
- Missing values (NA) indicate that mortality was not confirmed during the study period.
- radio_track: Indicates whether the individual was equipped with a radio/GPS transmitter.
- Values:
- 1 = telemetry-monitored individual
- 0 = no telemetry device
- Values:
- 2012–2024: Annual encounter history variables indicating whether an individual was detected during a given year through genetic monitoring and/or telemetry. These variables were used to construct capture–mark–recapture encounter histories for survival analyses.
- Values:
- 1 = individual detected
- 0 = individual not detected
- Values:
- Variable naming note: Depending on software import settings, annual encounter variables may appear with a leading X (e.g., X2012 instead of 2012) because column names beginning with numerals are automatically reformatted in some statistical software such as R.
Code/software
The dataset is provided as a comma-separated values (.csv) file and can be viewed with any standard spreadsheet or statistical software, including R, RStudio, Microsoft Excel, LibreOffice Calc, or similar programs.
Data processing, visualization, and statistical analyses were conducted in R (version 4.4.1). Capture–mark–recapture analyses and Bayesian survival models were implemented using JAGS interfaces in R.
The following R packages were used:
- coda — Markov chain Monte Carlo (MCMC) diagnostics and summaries
- R2jags — interface between R and JAGS
- ggplot2 — graphical visualization
- gridExtra — arrangement of graphical outputs
- dplyr — data manipulation and processing
The workflow consisted of:
- importing and formatting encounter-history data from the .csv file,
- constructing annual capture–mark–recapture histories,
- fitting Bayesian survival models,
- evaluating convergence and posterior distributions, and
- visualizing demographic parameter estimates.
No proprietary software is required to access the dataset itself.
Access information
Not applicable. The dataset was generated by the authors and is not derived from external public datasets.