Efficacy of three formulations of zinc phosphide for managing black-tailed prairie dogs

Abstract

We evaluated the effectiveness and cost of three zinc phosphide (Zn 3P 2) baits for managing black-tailed prairie dogs ( Cynomys ludovicianus). Sixty-six 0.4-ha treatment and paired control plots were delineated within 13 prairie dog colonies in central Nebraska. Treatment plots were prebaited with untreated stream-rolled oats according to Zn 3P 2 label directions. After 2–3 days, we applied each of the three formulations of Zn 3P 2 baits according to label directions to 22 randomly assigned treatment plots. Prairie dog activity was reduced 80% with Zn 3P 2-treated rolled oats (Pocatello Supply Depot, US Department of Agriculture-Wildlife Services, Pocatello, ID, USA); 78% with Zn 3P 2-treated crimped oats (Bell Laboratories, Inc., Madison, WI, USA), and 71% with Zn 3P 2-treated pellets (Bell Laboratories), as measured by a plugged burrow technique. No significant differences (P=0.342) in efficacy were detected among the three treatments. Material costs varied among the Zn 3P 2 treatments (rolled oats-$1.04 kg −1, crimped oats-$1.32 kg −1, and pellets-$2.21 kg −1). Each treatment, including prebaiting with untreated rolled oats, required 3.6 h ha −1 to apply. The total costs for 70% to 80% control of black-tailed prairie dogs (@ $5.00 h −1 labor) were $18.71 ha −1 for rolled oats, $18.82 ha −1 for crimped oats, and $19.16 ha −1 for pellets.