GIS-based multiple-scale study on scaled quail (Texas)

Studies on scaled quail (Callipepla squamata) abundance and its relationship to landscape structure were carried out at various spatial scales. Scaled quail have different population trends between winter and breeding seasons, based on long-term (1968–2000) and short-term (1983–2000) abundance data. Recently, scaled quail declined more rapidly in winter than in breeding season. They have significantly declined at the center of their range where scaled quail were abundant before, but they are relatively stable or increasing in the periphery of their range. Spatial-statistical approaches were used to examine spatial structure of scaled quail abundance between winter and breeding season. Scaled quail abundance in the breeding season has spatially-structured variances, which are closely associated with physiographic region.; Scaled quail abundance declined dramatically in the Rolling Plains (RP) during the last few decades, but was stable in the South Texas Plains (STP) ecoregion. Landscape pattern and change between RP and STP were quantified to assess the relationship between scaled quail abundance and landscape characteristics. Landscapes in the RP and the STP had considerably different composition and spatial arrangement of land-cover types. The STP landscapes had significantly more shrubland and less grassland/herbaceous and cropland/pasture cover; they were more fragmented, except for shrubland, with greater interspersion among land-cover classes. In the RP, grassland/herbaceous rangeland and cropland cover were essential to scaled quail habitat. Population decline in the RP may be related to the decrease of grassland/herbaceous and aggregation of cropland/pasture.; A landscape-scale habitat suitability model for scaled quail was developed and tested based on transect data for the RP and STP. Using spatial characteristics from classified land-cover data and original aerial photographs as habitat variables, this habitat suitability model can be used to predict spatial distribution of habitat suitability for food, cover, and reproductive requirements of scaled quail. Modification may be needed to apply this habitat suitability model in different regions, because the performance of the model showed spatial and temporal variability when evaluated against species abundance.