Data and code from: Integrating multiple-covariate distance sampling and habitat modeling to inform conservation of the Asian houbara in central Iran
Data files
Jan 28, 2026 version files 24.83 KB
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analysis.R
5.82 KB
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Asian_houbaras_data_-Distance_Sampling.csv
7.43 KB
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Asian_houbaras_data-_Habitat_Use.csv
1.54 KB
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Asian_houbaras_data-Distance_Sampling(High-Low).csv
7.32 KB
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README.md
2.72 KB
Abstract
Reliable estimates of abundance and habitat associations are critical for conserving low-density species such as the Asian houbara (Chlamydotis macqueenii). Despite its vulnerable global status, robust estimates of houbara population size and habitat requirements remain scarce across much of its range. We combined multiple-covariate distance sampling (MCDS) with habitat modeling (Random Forest, GAMs, and GLMs) to estimate density and identify habitat relationships of houbaras in central Iran. In spring 2022, 223 line-transect surveys (1,449 km) covering a 10,000 km2 area yielded 205 individuals across 67 detections. The best-supported MCDS model included fine gravel cover (positive) and vegetation height (negative) as detectability covariates, though their effects were weak. This model estimated a density of 0.53 individuals/km2 (95 % CI: 0.37–0.75), corresponding to ~5,293 individuals (95 % CI: 3,778–7,473). Estimates were nearly identical to those from the best conventional distance sampling (CDS) model, indicating that detectability covariates did not materially improve model accuracy. However, habitat models consistently identified fine gravel cover and vegetation height as the most influential predictors, underscoring their ecological relevance for habitat use. Results indicate an ongoing population decline relative to previous regional estimates, highlighting the need for continued monitoring. Integrating population estimation with habitat modeling provides a practical framework for improving conservation assessments of the Asian houbara and other ground-dwelling birds in open habitats. Conservation actions should prioritize the protection and management of suitable habitats, supported by standardized survey protocols that improve population assessments and inform management decisions.
Dataset DOI: 10.5061/dryad.hmgqnk9z4
Description of the data and file structure
This supplementary dataset, integral to the associated research article, contains all data necessary for understanding and reproducing the analyses conducted in this study on the distribution, density, and habitat associations of the Asian houbara. The dataset includes transect‐based survey records, detection and distance‐sampling data, environmental and microhabitat measurements, and derived variables used in population estimation and predictive modeling. These data support analyses of density estimation and evaluation of environmental drivers using multiple statistical and machine‐learning approaches. The Excel files provided in this repository contain both raw and processed datasets required for interpretation, replication, and further comparative analyses, thereby promoting transparency, reproducibility, and reuse in ecological and conservation research. Additionally, an R script included in the repository contains all necessary code to reproduce the analyses presented in the study.
Files and variables
File: Asian_houbaras_data_-Distance_Sampling.csv
Description:
Variables
- Region.Label:Province: Isfahan Province, Iran
- Area:Study area size: 10000 km2
- Sample.Label: Transect Name
- Effort: Sampling effort
- distance: Perpendicular distance
- size: Size of each cluster
- BSH: bush cover percentage
- SHB: shrub cover percentage
- CR : coarse gravel percentage
- FN: fine gravel percentage
- MM : medium gravel percentage
- SD: sand cover
- HT: average vegetation height
File: Asian_houbaras_data-_Habitat_Use.csv
Description:
Variables
- Bush: bush cover percentage
- Shrub: shrub cover percentage
- Coarse : coarse gravel percentage
- Fine: fine gravel percentage
- Medium: medium gravel percentage
- Sand: sand cover
- Height: average vegetation height
- Observation: number of Houbara in cluster
File: Asian_houbaras_data-Distance_Sampling(High-Low).csv
Description:
Variables
- Region.Label: Isfahan Province, Iran
- Area: 10000 km²
- Sample.Label: Transect Name
- Effort: Sampling effort
- distance: Perpendicular distance
- size: size of each cluster
- BSH: bush cover percentage
- SHB: shrub cover percentage
- CR : coarse gravel percentage
- FN: fine gravel percentage
- MM : medium gravel percentage
- SD: sand cover
- HT: average vegetation height
Code/software
Use the included file analysis.R. Analyses done in R.
