LOST BIRD-YEARS: QUANTIFYING BIRD INJURIES IN NATURAL RESOURCE DAMAGE ASSESSMENTS FOR OIL SPILLS1

Abstract

ABSTRACT Large oil spills routinely impact hundreds or even thousands of birds. In order to determine the compensation that responsible parties owe the public, trustee agencies typically examine the number of live and dead birds collected to estimate total bird mortality caused by the spill (Ford et al., 1987). In these natural resource damage assessments (NRDA), compensation is typically based upon the potential ecological benefits that flow from a restoration project. In the case of a bird kill, final compensation is based upon the cost of implementing a restoration project and not upon a dollar value per bird. The dominant paradigm for calculating compensatory restoration for bird injuries is Resource Equivalency Analysis (REA). This paper begins by providing a brief overview of REA when applied to birds. We then examine the REA implications of varying the level of mortality, baseline variability, and demographic variables in a simple population model that tracks both injured and baseline population levels. After finding no evidence that these factors necessarily produce short recovery times, we summarize two general approaches for calculating lost bird-years. We conclude that short recovery times (e.g., one-year) are unlikely for birds when using individual-based measures of injury. Further, we believe that recovery times may be much longer than currently calculated for situations where plausible “recovery mechanisms” cannot be defined.