In the longleaf pine ecosystem (Pinus palustris) of the southeastern United States, prescribed fire is necessary to restore and maintain habitat for grassland birds, the majority of which have experienced steep population declines in the last few decades. Red imported fire ants (RIFA, Solenopsis invicta) are an invasive species whose density may increase in response to disturbances, such as fire. This potential increase is of concern because over 60 bird species that require fire-maintained grasslands are vulnerable to RIFA nest predation, such as the federally endangered red-cockaded woodpecker (Picoides borealis) and northern bobwhite quail (NOBO, Colinus virginianus). RIFA nest predation rates on NOBO vary across similarly managed longleaf pine systems, indicating that other environmental factors may influence RIFA nest predation beyond fire disturbance. Based upon these differences, we hypothesized that RIFA mound density and forager abundance (i.e. level of activity) are both driven by soil type, groundcover type, and time since burn. To investigate what influences RIFA prevalence, mound surveys and pitfall trapping were conducted on nine properties in Florida and Georgia managed with frequent fire. Pitfall trapping is being used to estimate RIFA forager abundance, but also provided a way to evaluate other ant species and ground invertebrates. RIFA prevalence will be compared to time since burn, groundcover type, soil type, and interactions of these variables. General invertebrate and ant biodiversity will be compared to these environmental variables as well as RIFA prevalence, as there is an ongoing debate in the literature about how RIFA presence impacts invertebrate biodiversity.
Results/Conclusions
Preliminary results indicate that there is a relationship with RIFA mound density and our three variables of interest. Significantly higher mound density is present in sites that have not been burned in a year, sandier soils, and in old-field groundcover (historically agricultural). This information can be helpful to land managers conserving native bird species like the NOBO. Treating an entire property for RIFA is an expensive enterprise, but if managers can target specific areas for RIFA control, it will be more financially feasible for them to manage this invasive and its impacts on native species. Our findings fill an important gap in understanding how RIFA invasions and predation may be related to restoration and disturbance. Furthermore, our research helps to elucidate basic biological invasion problems and guide management efforts targeted towards native species in fire-mediated landscapes.