Spatial patterns of kangaroo density across the South Australian pastoral zone over 26 years: aggregation during drought and suggestions of long distance movement

摘要: 1. Wildlife surveys usually focus on estimating population size, and management actions such as commercial harvesting, culling poison baiting are referenced commonly to size alone, without taking into account the way in which those animals distributed. This paper outlines how point-based aerial survey data can be converted continuous density surfaces using spatial analysis techniques. Using this approach, we describe explore patterns of two species kangaroos an area exceeding 200 000 km2 South Australia over a 26-year period. 2. Densities red western grey were estimated 2 km_2 segments along transect lines, yielding point estimates. Universal kriging provided unbiased interpolation these autocorrelation structure described by semi-variogram. The Getis statistic identified clusters high low kangaroo density. 3. Considerable year-to-year variation was observed. In many cases, annual rates increase large areas too explained vital implying immigration from surrounding areas. These shifts distribution occasionally that had received better rainfall than For both species, there no obvious local pattern or clustering beyond average present set regions, suggesting latter appropriate divisions for harvest management. 4. Data fitted power law relationship extremely well. During dry times, kangaroos, but not more aggregated, supporting past ground observations at fine scale. 5. Synthesis applications. Kriged enable estimation individual properties, units quotas approvals allocated. estimates will marked improvements systematic sampling when intensity is low. Predictions satellite imagery allow accurate allocation quotas. Similarly, predictions even dispersion following managers anticipate downturns rate.