Estimating Drc-1339 Mortality Using Bioenergetics: A Case Study of European Starlings

We developed a bioenergetics model for European starlings (Sturnus vulgaris) that estimated mortality from baitings with CU Bird Carrier pellets treated with 1% DRC-1339 Concentrate and diluted 5:1 (untreated:treated pellets). A bioenergetic analysis of heat and radiative energy exchanges between the starling body surface and surrounding environment was converted to daily caloric demand based on a steady-state energy balance. The amount of Bird Carrier eaten per starling was governed by subroutines in the model that used probability distributions to simulate variability in dietary intake at the bait site. Mortality was estimated through dose-response regression analysis. Compared to onsite pre- and post-baiting counts conducted during winter 2004-2005 at 33 Midwestern dairies, model estimates were greater for 23 of the 33 counts. Onsite counts estimated 148 mortalities/kg pellets removed from the site compared to 204/kg for the model. The model was programmed in Visual Basic© with Microsoft® Excel 2002 as the platform. The model requires input of 11 variables, including ambient temperature, latitude, wind speed, and amounts of bait applied and remaining. The model can be modified for use with other bird species, baits, dilutions, and concentrations