Red Imported Fire Ant Impacts on Northern Bobwhite Populations

Abstract

The stability of Northern Bobwhite (Colinus virginianus) populations in Texas, where high density polygyne red imported fire ants (Solenopsis invicta) account for >50% of all (S. invicta) colonies, has been cited as a reason to repudiate impacts by this exotic species on Northern Bobwhite. We used two approaches to investigate the relationship between red imported fire ants and Northern Bobwhite. In the first approach, we used correlation analysis to compare Northern Bobwhite abundance trends, determined from Christmas Bird Count data in 15 Texas counties, before and after fire ant infestation. Before red imported fire ant infestation, no significant trend in Bobwhite abundance existed (r = ‐0.355, P = 0.314). After fire ant infestation, Northern Bobwhite abundance declined and was highly negatively correlated with years of infestation (r = ‐0.867, P < 0.001). Bobwhite populations from 16 uninfested counties in Texas revealed no trend over a 27‐yr (1966‐1992) period (r = ‐0.081, P = 0.688). In the second approach, red imported fire ant populations were reduced on five 202‐ha study areas in the Texas Coastal Bend; autumn Northern Bobwhite densities were monitored for 2 yr on those reduced areas and five untreated areas. By the 2nd yr, Bobwhite autum density was higher (P = 0.028) on areas where red imported fire ants were suppressed. We concluded that polygyne red imported fire ants were negatively impacting Northern Bobwhite in this region of Texas.