Kori Bustards (Ardeotis kori) respond to vegetation density and elevation in the Northern Tuli Game Reserve, Botswana

Abstract

Conservation planning and decision making for species of concern requires precise information on abundance and habitat associations. We conducted transect surveys throughout the Northern Tuli Game Reserve, Botswana during June-July 2014 and May-July 2015 to estimate the occupancy and abundance of Kori Bustards (Ardeotis kori). The probability of occupancy of Kori Bustards was greater in areas with tree canopy cover ≤ 50% (ψ2014 = 0.37, SE ± 0.09; ψ2015 = 0.39, SE ± 0.06) when compared with areas with tree canopy cover > 50% (ψ2014 = 0.00, SE ± 0.00; ψ2015 = 0.00, SE ± 0.00). Densities of Kori Bustards ranged from 0.03-5.02 individuals/km² at our study sites. They showed annual variation, and densities were highest in areas where vegetation was classified as sparse or bare soil. Areas at low (≤ 540 m above sea level) and high (≥ 540 m above sea level) elevations at our study sites also exhibited differences in density of Kori Bustards but elevational differences varied among years. Areas categorized as both sparse vegetation and higher elevation had the highest estimated densities in 2014 with 5.02 individuals/km². Areas categorized as sparse vegetation and lower elevation had the highest densities in 2015 with 2.20 individuals/km². Our study demonstrates that areas of sparse vegetation and open canopy areas are important to Kori Bustards. However, open canopy areas outside of reserves may be at risk of conversion to row crop and other forms of agriculture as human populations and demands for food increase. Habitat-specific information will be useful for future studies to identify risks during landscape conservation planning within the range of the Kori Bustard.

Keywords

• conservation
• density estimation
• distance sampling
• occupancy analysis