Application of pesticides may have serious adverse consequences in environment. Birds are one of the most important non-target species that are harmed by agricultural chemical pesticides. In the current study, Monte Carlo optimization based Quantitative Structure Toxicity Relationship (QSTR) analyses were performed on a dataset containing diverse chemical pesticides with toxicity data determined on Bobwhite quail. Hybrid models containing SMILES and graph based descriptors were developed on three different training and test set combinations. The best model was selected based on validation statistics on internal training (n = 96) and external test (n = 31) as well as validation (n=25) sets. The best model was thoroughly analyzed to understand structural requirements of the chemical pesticides for higher avian toxicity. The models developed in the current analyses may be useful to design novel less toxic pesticides.