Hazards to Birds and Mammals Following Nifluridide Baiting for Controlling Fire Ants

Hazards to birds and mammals were evaluated following the aerial application of 0.75% nifluridide (EL-468) bait for controlling imported red fire ants (Solenopsis invicta). Birds were recorded on 12 transects (6 treated and 6 control) pre- and posttreatment. Small mammal abundance was estimated by live trapping 6 plots (3 treated and 3 control) pre- and posttreatment. Bait disappearance rates were measured for 3 different densities of red fire ant mounds. Overall, more birds and small mammals were counted posttreatment than pretreatment. Posttreatment ingress by northern cardinals (Cardinalis cardinalis), dickcissels (Spiza americana), and indigo buntings (Passerina cyanea) accounted for most of the increase, Conversely, 10 bird species with recognizable territories showed a population decline posttreatment on the treatment area, but the reductions were not statistically different from the control area (P > 0.20). However, of these 10, the disappearance of well-documented territories of 3 low-foraging insectivorous species (white-eyed vireo [Vireo griseus], Swainson's warbler [Limnothlypsis swainsonii], and common yellowthroat [Geothlypis trichas]) occurred at, or shortly after, treatment. The number of small mammals increased on 5 of the 6 plots posttreatment. During the posttreatment searching period, no carcasses were found that were attributed to treatment. These data suggest that no significant primary poisoning occurred to passerine birds or small mammals after the aerial application of nifluridide bait. However, in future applications of nifluridide bait to brushy or wooded habitats, its potential effects on low-foraging insectivorous birds should be further investigated.

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