Premium
An index technique to monitor broadcast calibration and bait pick up, plus rodent and avian sign under arid conditions
Author(s) -
Sterner Ray T,
Ramey Craig A
Publication year - 2002
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.468
Subject(s) - vole , microtus , pheasant , zoology , biology , toxicology , ecology , population , medicine , environmental health
As part of product‐performance and wildlife‐hazards studies of 2% zinc phosphide (Zn 3 P 2 ) steam‐rolled‐oat baits (11.2 kg ha −1 ) to reduce vole populations ( Microtus spp ) in alfalfa ( Medicago sativa ), we used randomly located, brushed‐dirt plots (eight ∼930−cm 2 plots per 0.2‐ha enclosure) to monitor bait‐broadcast and ‐removal patterns, as well as to index vole and avian sign. Research was conducted in 18 × 0.2‐ha enclosures containing 2.5‐year‐old stands of alfalfa; a 2‐day pre‐bait (placebo baits broadcast in all enclosures) period followed by a 14‐day test‐bait period (placebo and 2% Zn 3 P 2 baits in nine enclosures each) characterized the bait exposures. Baits were broadcast manually by two certified pesticide applicators (CPAs) using Spyker® Model‐75 spreaders. Baits that fell onto plots were counted <30 min later to assess the uniformity of bait distribution. The main statistical design was a 2 (placebo or Zn 3 P 2 baits) × 3 (vole‐only, vole–pheasant, vole–quail exposures) × 14 (days) factorial, with days considered repeated measurements. In the six vole‐only enclosures, baits were removed from the brushed‐dirt plots and replaced with four 0% or 2% Zn 3 P 2 baits (one per 232.6‐cm 2 quadrant; 32 per enclosure); these ‘placed’ baits were then monitored daily for removal, while the surfaces of all plots were monitored daily for the presence : absence of animal/bird sign. Key results were: (a) 3.51 (±2.66) and 3.39 (±3.52) mean (±SD) baits were found on plots after pre‐bait and test‐bait broadcasts, respectively—less than the predicted 4.52 particles per 930‐cm 2 plot; (b) baits ‘placed’ on plots in placebo‐baited enclosures were removed earlier than those in Zn 3 P 2 ‐baited enclosures—data in agreement with observed vole mortality; and (c) species × bait interactions occurred for both the vole‐ and pheasant‐sign counts, but not quail‐sign counts—data also indirectly confirming Zn 3 P 2 ‐induced mortality effects on voles and pheasants. This technique has utility for a variety of wildlife biology and chemical registration studies; although limited to arid conditions, the technique affords useful indices of broadcast calibration, bait pick‐up, as well as target and non‐target species mortality. Published in 2002 for SCI by John Wiley & Sons, Ltd