The Effect of Red Imported Fire Ants and Invertebrate Abundance on Northern Bobwhite Abundance

Abstract

The northern bobwhite (Colinus virginianus; hereafter bobwhite) has experienced significant declines over the past decades. Few studies have documented the effects red imported fire ants (Solenopsis invicta; hereafter RIFA) have on bobwhites, however, further research is needed to address different aspects of RIFA and bobwhite interactions. RIFA will predate on invertebrates, an important food source for nesting bobwhites and chicks; evaluating the effect RIFA have on bobwhites and/or invertebrates will help determine if RIFA are contributing to the decline.

My study took place at the Attwater Prairie Chicken National Wildlife Refuge in Colorado and Austin counties, Texas. I had 3 study sites; 2 in Colorado County (treated for RIFA/with predator control and non-treated/with predator control) and 1 in Austin County (non-treated/without predator control). Two-thirds of the refuge in Colorado County was aerially treated with Extinguish Plus®, a highly attractive ant control substance. I sampled invertebrates and RIFA on all 3 sites and I also trapped bobwhites on the 2 sites in Colorado County using funnel traps. Both sexes were banded and females were fitted with a radio collar. I used ANOVA to determine differences in invertebrate numbers and biomass on the 3 sites. I found greater (P < 0.001) invertebrate biomass in the Colorado County/non-treated site compared to the other 2 sites and greater (P = 0.015) invertebrate numbers in the Austin County site compared to the Colorado County/non-treated site. I found significantly (P < 0.001) more RIFA in the Austin County site than the other 2 sites. I captured 349 bobwhites from March 2016 through May 2017. Bobwhite relative abundance for 2016 was 87 (95% CI = 47–108), 60 in treated and 27 in non-treated area; for 2017, bobwhite relative abundance was 53 (95% CI = 36–70), 43 in treated site and 10 in non-treated site. I rejected my hypothesis that I would find more bobwhites in areas with lower RIFA as well as in areas with greater invertebrate biomass and numbers. Therefore, it appears that treatment for RIFA had no effect on bobwhite abundance, however; major flooding on 18 April 2016 may have influence my results.