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A spatially explicit model for estimating risks of pesticide exposure to bird populations
Citation:
Etterson, M., N. Schumaker, K. Garber, S. Lennartz, A. Kanarek, AND J. Connolly. A spatially explicit model for estimating risks of pesticide exposure to bird populations. American Ornithological Society Annual Meeting, East Lansing, Michigan, July 31 - August 04, 2017.
Impact/Purpose:
This poster describes a linked series of USEPA models that can be used for avian population-level risk assessment. The work described represents an ongoing collaboration between ORD and OPP/EFED to increase the realism and relevance of pesticide risk assessment for birds, including federally listed populations and species under the Endangered Species Act. In it, the authors demonstrate how the three linked models (TIM, MCnest, and HexSim can be combined in a single workflow to produce a comprehensive spatially explicit risk assessment for two pesticides for a federally listed species, the California Gnatcatcher (Polioptila californica). The intended audience includes federal management agencies, especially USEPA, US Fish and Wildlife Service, and National Marine Fisheries Service as well as both the chemical risk assessment community and the avian modeling communities.
Description:
Pesticides are used widely in US agriculture and may affect non-target organisms, including birds. Some pesticide classes (e.g., acetylcholinesterase inhibitors) are known or suspected to cause direct mortality to birds, while others (e.g., synthetic pyrethroids, neonicotinoids) may have sublethal impacts. We developed an integrated modeling workflow to conduct spatially explicit population level risk assessment for birds in agroecosystems that may be exposed to pesticides. The integrated workflow includes three existing USEPA models, the Terrestrial Investigation Model (TIM), the Markov Chain Nest Productivity Model (MCnest), and the HexSim modeling environment. The integrated model is parameterized using data required for pesticide registration under the Federal Insecticide Fungicide Rodenticide Act (FIFRA), together with species life history data available in the scientific literature. We demonstrate the model by simulating potential pesticide effects on the federally threatened California Gnatcatcher (Polioptila californica), within the U.S. portion of the species range. We simulated impacts from two insecticides, malathion (organophosphate), and λ-cyhalothrin (pyrethroid), applied to wheat crops in a manner consistent with registered labels for the two pesticides. We show declines in gnatcatcher abundance and changes in the distribution of the species following applications of each pesticide. The integrated TIM/MCnest/HexSim model is intended to allow risk assessors to evaluate spatial and temporal dynamics that are essential to understanding population persistence in complex spatial landscapes with multiple stressors.