A new ecological risk assessment procedure using resource selection models and geographic information systems

Quantitative assessment of risk (value) to animals or populations resulting from management actions, accidental impacts, or natural changes in wildlife or fish habitat has proven to be elusive. For situations in which researchers are fortunate enough to have data allowing estimation of a resource selection function (RSF) for an animal or a population, we propose a quantitative measure of risk or value of habitat changes. The RSF provides a response surface of estimated relative probability of use of resource units within an area that can be computed both before and after changes in the unit characteristics. The change in volume under the response surface yields an intuitive index of risk (value) associated with habitat (resource) changes that directly measures a component of the total risk of changes to animals or populations. The method is particularly convenient if used in conjunction with data from a geographic information system (GIS). We provide an illustration where risk of timber harvest to the foraging behavior of a pair of northern spotted owls (Strix occidentalis caurina) was assessed.