EFFICACY OF 3 FORMULATIONS OF ZINC PHOSPHIDE FOR MANAGING BLACK-TAILED PRAIRIE DOGS

We evaluated the effectiveness and cost of three zinc phosphide (Zn3P2 ) baits for managing black-railed prairie dogs (Cynomys ludovicianus). Sixty-six 0.4-ha treatment and paired control plots were delineated w ithin 13 prairie dog colonies in central Nebraska. Treatment plots wer e prebaited with untreated stream-rolled oats according to Zn3P2 label directions. After 2-3 days, we applied each of the three formulations of Zn3P2 baits according to label directions to 22 randomly assigned treatment plots. Prairie dog activity was reduced 80% with Zn3P2-treat ed rolled oats (Pocatello Supply Depot, US Department of Agriculture-W ildlife Services, Pocatello, ID, USA); 78% with Zn3P2-treated crimped oats (Bell Laboratories, Inc., Madison, WI, USA), and 71% with Zn3P2-t reated pellets (Bell Laboratories), as measured by a plugged burrow te chnique. No significant differences (P = 0.342) in efficacy were detec ted among the three treatments. Material costs varied among the Zn3P2 treatments (rolled oats-$1.04 kg(-1), crimped oats $1.32 kg(-1), and p ellets-$2.21 kg(-1)). Each treatment, including prebaiting with untrea ted rolled oats, required 3.6 h ha(-1) to apply. Thr total costs for 7 0% to 80% control of black-tailed prairie dogs (@ $5.00 h(-1) labor) w ere $18.71 ha(-1) for rolled oats, $18.82 ha(-1) for crimped oats, and $19.16 ha(-1) for pellets. (C) 1998 Elsevier Science Ltd. All Fights reserved.