LOST BIRD-YEARS: QUANTIFYING BIRD INJURIESIN NATURAL RESOURCE DAMAGE ASSESSMENTSFOR OIL SPILLS

摘要

Large oil spills routinely impact hundreds or even thousands ofrnbirds. In order to determine the compensation that responsiblernparties owe the public, trustee agencies typically examine thernnumber of live and dead birds collected to estimate total birdrnmortality caused by the spill (Ford et al., 1987). In these naturalrnresource damage assessments (NRDA), compensation is typicallyrnbased upon the potential ecological benefits that flow from arnrestoration project. In the case of a bird kill, final compensation isrnbased upon the cost of implementing a restoration project and notrnupon a dollar value per bird.rnThe dominant paradigm for calculating compensatory restorationrnfor bird injuries is Resource Equivalency Analysis (REA). Thisrnpaper begins by providing a brief overview of REA when appliedrnto birds. We then examine the REA implications of varying the levelrnof mortality, baseline variability, and demographic variables in arnsimple population model that tracks both injured and baselinernpopulation levels. After finding no evidence that these factors necessarilyrnproduce short recovery times, we summarize two generalrnapproaches for calculating lost bird-years. We conclude that shortrnrecovery times (e.g., one-year) are unlikely for birds when usingrnindividual-based measures of injury. Further, we believe that recoveryrntimes may be much longer than currently calculated forrnsituations where plausible “recovery mechanisms” cannot berndefined.