The effects of red imported fire ants on white-tailed deer fawns



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Texas Tech University


Since being accidentally imported into the United States in the 1930's, the red imported fire ant [{Solenopsis invicta Buren); RIFA] has had a definable impact on wildlife, agriculture, and industry. A study in the Texas Coastal Prairie demonstrated a significant decrease in white-tailed deer {Odocoileus virginianus) fawn recruitment in RIFA infested areas. Our objective was to test whether mechanisms exist whereby RIFA could affect white-tailed deer fawn survival. We tested whether deer fawns exhibit behaviors that would preclude or reduce direct mortality due to RIFA stings. We hypothesized that RIFA presence would increase fawn movements during the first days after birth, increasing the susceptibility of fawns to predation. Red imported fire ant stings may also alter other fawn behaviors, including increasing licking rate and decreasing nursing rate, which could potentially reduce fawn survival. Red imported fire ants were chemically removed from four enclosures, while four others contained naturally occurring densities of RIFA colonies. We observed behavior of 19 fawns in 1998 and 17 in 1999 from birth to 28 days old and monitored RIFA-fawn encounter intensity in all enclosures using bait cups. No RIFA-induced fawn mortality occurred. Fawns moved to avoid RIFA stinging when irritated, although frequency of fawn movement was not significantly altered in the presence of RIFA. Increased licking and decreased nursing was evident. At the colony density tested, RIFA do not appear to pose a threat to fawn survival at the population level. However, isolated instances of altered fawn behavior due to RIFA stings such as erratic running, jumping, head shaking and bleating did occur that would increase the risk of predation in uncontrolled environments.