Probabilistic model for estimating field mortality of target and non-target bird populations when simultaneously exposed to avicide bait

Authors

John J. Johnston, USDA/APHIS/WS National Wildlife Research CenterFollow
Melvin J. Holmes, DEFRA, Central Science Laboratory
Andy Hart, DEFRA, Central Science Laboratory
Dennis J. Kohler, USDA/APHIS/WS National Wildlife Research CenterFollow
Randal S. Stahl, USDA-APHIS-Wildlife ServicesFollow

Date of this Version

January 2005

Comments

Copyright 2005 Society of Chemical Industry

Abstract

A probabilisticmodel was developed to estimate target and non-target avian mortality associated with the application of the avicide CPTH (3-chloro-p-toluidine hydrochloride) to minimize sprouting rice damage in the southern USA. CPTH exposures for individual birds were predicted by random sampling from species-specific non-parametric distributions of bait seed consumption and CPTH residues detected on individual bait seeds. Mortality was predicted from the species-specific exposure versus mortality relationship. Individual variations in this response were captured in the model by Monte Carlo sampling from species-specific distributions of slopes and median toxicity values (LD50) for each bird. The model was used to simultaneously predict mortality (percentage of exposed population and number of birds killed/weight of consumed bait) for a target (blackbird) and non-target (mourning dove) species feeding on bait sites for up to five consecutive days.