Effect of red imported fire ant (Solenopsis invicta Buren) on the nesting success of Northern Bobwhite (Colinus virginianus L.)

The Northern Bobwhite (Colinus virginianus L.) has experienced average yearly decline of 3% in the United States from 1966-2005. Factors implicated in decline include habitat destruction, alteration of farm practices, and red imported fire ant (RIFA) (Solenopsis invicta Buren). Effect of RIFA on bobwhites has been a hot topic leading to formation of polarized camps – those who believe RIFA have little effect and those who believe the effect will further threaten the species’ survival. The main objective of this study was to determine if RIFA affect nesting of bobwhites and at what stage in nesting birds are most vulnerable. Effect of broadcast-spread fire ant bait on RIFA and non-target ant species also was studied. In 2005, eight 4.45 ha plots, each with one aviary housing breeding bobwhites from Louisiana captive stock, were paired by habitat feature. Four plots were broadcast-treated aerially with Amdro® (0.73% hydramethylnon). Sticky traps indicated successful dispersal of bait, although percent composition of particle size on traps differed from that expected. Food traps were used to measure success of RIFA suppression and to determine effect of bait on non-RIFA ants. In 2006, number of plots was reduced to six (three pairs), but number of aviaries per plot increased to four. Two aviaries per plot contained captive-bred bobwhites from Arkansas, whereas the other two contained Louisiana captives. In addition to RIFA, which was successfully suppressed on treated plots, Aphaenogaster fulva-rudis-texana was negatively affected by treatment. Data from other myrmecines suggested similar patterns of decrease by treatment. Only Prenolepis imparis showed a possible competitive release from RIFA. In 2005, lack of nesting reduced number of replicates. One nest hatched successfully; another failed – overrun by RIFA. In 2006, mean number of nests, eggs, and chicks did not differ significantly between treated and untreated plots nor between the two populations of bobwhites. A significantly greater proportion of AR and LA nests were attacked by RIFA on untreated plots. Three nests hatched successfully on treated plots versus one on untreated. RIFA appear to breach intact bobwhite eggshells. In areas of sympatry, RIFA may exacerbate bobwhite decline by attacking eggs prior to hatch