EFFECT OF VERTEBRATE PESTICIDES ON NON-TARGET WILDLIFE POPULATIONS - EVALUATION THROUGH MODELING
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abstract
A general modelling methodology to evaluate the potential effects of pesticides on non-target wildlife populations is described, and its use within a resource management framework is demonstrated. Attention is focused on (1) interfacing relatively simple numerical and analytical procedures with available data to specify initial baseline population parameters, (2) representing density-dependent relationships affecting non-target natality and survival rates, and (3) interpreting simulated non-target population responses to different pesticide-use schemes within a management framework. The methodology involves use of a Leslie matrix model with variable age-specific natality and survival rates. Natality and survival rates can vary as a function of non-target population density, the density of competitor, predator, and/or prey populations, and/or abiotic environmental factors. Required model input includes estimates of initial density of the non-target population, age-specific natality rates, the relative magnitudes of age-specific survival rates, the relationship of natality and survival rates to the appropriate population densities and/or abiotic environmental factors, and the magnitude of pesticide-induced mortality. Model output includes estimates of the density of the non-target population over time, the mean lowest density reached, the mean recovery time, and the probability of extinction resulting from a specified scheme of pesticide use. Use of the model within a management framework is demonstrated by evaluating the effects of four hypothetical coyote control schemes, using Compound 1080, on great horned owl populations in the United States. 1984.
