Habitat Selection by the Invasive Species Burmese Python in Southern Florida
Burmese Pythons (Python bivitattus) are large generalist predators that have established an expanding breeding population in Florida. As a first step in understanding current distributions, and therefore spread potential, we assessed diurnal habitat selection by Burmese Pythons in the southern Everglades using radiotelemetry. Sixteen individual pythons were radio-tracked between September 2006 and December 2009. Habitat variables included land cover, habitat edges, surface water depth, and change in water depth. Python locations were compared to available habitat, both within each snake's home range and across the entire study area, by calculating selection ratio intervals and developing resource selection functions. Habitat selection by Burmese Pythons in south Florida was nonrandom with clear selection of broad-leafed and coniferous forest and avoidance of open water and other habitats with deep water. We concluded that Burmese Pythons selected habitats with a substantial canopy overstory that was without deep flooding, with no strong selection for freshwater emergent macrophyte marsh habitats that dominate (∼ 43%) the study area. We will use these new quantitative insights into python habitat selection to model the potential for this invasive species to expand to new areas within Florida.Abstract
Map of the entire study site domain including the southern Everglades and adjacent urban regions located in Miami-Dade and Monroe Counties, Florida, showing the combined land cover categories. The red outline shows the study area used in the overall analysis, limited to most of Everglades National Park (502,942 ha). Home ranges for individual telemetered pythons are depicted as polygons with (males, red; females, yellow).
Type III selection ratio intervals (Wi) for surface water depth using radio-tagged Burmese Python locations within their home ranges. The x-axis gives the water depth intervals, every 5 cm, within a 0–65-cm range. Global selection ratio values are plotted along with standard error bars. Selection ratio values > 1 indicate selection; values < 1 indicate avoidance; values = 1 indicate no selection. Data points ≥ 50 cm had a single measurement at each depth (SE = 0).
Type III selection ratio intervals (Wi) for change in water depth using radio-tagged Burmese Python locations within their home ranges. The x-axis gives the water depth intervals, every 5 cm, ranging from −50–40 cm. Global selection ratio values are plotted along with standard error bars. Selection ratio values > 1 indicate selection; values < 1 indicate avoidance; values = 1 indicate no selection.
Type III selection ratio intervals (Wi) for land cover using radio-tagged Burmese Python locations within their home ranges. The x-axis gives the individual land cover classifications (excluding agriculture and urban because of insufficient data). Global selection ratio values are plotted along with standard error bars. Selection ratio values > 1 indicate selection; values < 1 indicate avoidance; values = 1 indicate no selection.
Type II selection ratio intervals (Wi) for land cover using radio-tagged Burmese Python locations across ENP. The x-axis gives the individual land cover classifications (six categories described in Materials and Methods excluding agriculture and urban because of insufficient data). Global selection ratio values are plotted along with standard error bars. Selection ratio values > 1 indicate selection; values < 1 indicate avoidance; values = 1 indicate no selection.
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