For longleaf pine ecosystems (Pinus palustris) in the Southeastern United States, prescribed fire is necessary for restoration and maintenance. However, fire may increase the abundance of invasive red imported fire ants (RIFA, Solenopsis invicta). This potential increase is of concern because >60 bird species that require fire-maintained grasslands are vulnerable to RIFA nest depredation, such as the culturally and economically important Northern bobwhite quail (NOBO, Colinus virginianus). RIFA nest depredation rates on NOBO vary across similarly managed longleaf pine systems, indicating that other factors influence RIFA beyond fire. We hypothesized that RIFA mound density and forager abundance (i.e. level of activity) are driven by soil type, groundcover type, and time since burn. To test our hypotheses, we conducted line-transect mound surveys and pitfall trapping on 11 properties in Florida and Georgia managed with frequent fire. Pitfall trapping was used to estimate RIFA forager abundance and how their presence may influence general ant biodiversity, which is the subject of ongoing debate in the literature. Factors affecting mound density will be investigated using a Poisson generalized linear mixed effects model, while the abundance of RIFA foragers and other ant species will be used in an occupancy analysis.
Results/Conclusions
Results indicate that there is a relationship with RIFA mound density and soil type, groundcover type, and time since burn. Significantly higher mound density was present in sites that have not been burned in a year, had sandier soils, and were historically agricultural. Analysis of pitfall trap data is ongoing. Preliminary work does not indicate a correlation between RIFA forager abundance and ant biodiversity. Our findings address an important gap in understanding how RIFA invasions and relate to restoration management and modern impacts of land use history. From this work, we cannot recommend land managers conserving native bird species like the NOBO treat entire properties for RIFA, as the expense outweighs the benefits. However, if managers can target specific areas for RIFA control, it will be more financially feasible to manage this invasive and its impacts on native species.