Use of Oil-Affected Habitats by Birds After the Exxon Valdez Oil Spill

Abstract

This study investigated the effects of the Exxon Valdez oil spill on the use of oil-affected habitats by birds during 1989–1991. We measured densities of birds in bays that had been subjected to various levels of oiling from the spill during survey cruises that were conducted throughout the year in Prince William Sound (PWS) and during summer along the Kenai Peninsula. Overall, 23 of 42 (55%) species in PWS and 22 of 34 (65%) species on the Kenai showed no evidence of oiling impacts on their use of habitats. Most species that did show initial negative impacts had recovered by late summer 1991 when our study concluded, although 6 of the 19 species initially impacted in PWS and 6 of the 12 species initially impacted along the Kenai did not exhibit clear signs of recovery by this time. A Principal Components Analysis of species examined from PWS revealed extensive overlap in ecological attributes among species that were and were not negatively impacted in their use of oil-affected habitats. Species that did not show clear evidence of recovery tended to be intertidal feeders and residents of PWS, but other ecologically similar species evidenced either no initial impacts or rapid recovery. These similarities suggest that the prognosis is good for the species for which we were unable to document recovery in habitat use. Our findings, together with the rapid rates of recovery in habitat features reported in other studies, suggest that impacts of the Exxon Valdez oil spill on avian use of oil-affected habitats generally were not persistent.

Quantifying population‐level risks using an individual‐based model: Sea otters, Harlequin Ducks, and the Exxon Valdez oil spill

“…Within weeks of the oil spill, concerns were expressed about potential persistent adverse toxic effects on Harlequin Ducks from ingesting oiled prey, especially mussels (Patten et al 2000). Some studies conducted several years after EVOS have reported decreased abundance, attributing it to: 1) reduced overwintering survival of females and/or unsuccessful reproduction caused by EVOS (Esler et al 2002; Patten et al 2000), 2) degraded habitat quality not associated with EVOS (Day et al 1995, 1997; Irons et al 2000; Wiens et al 2004), or 3) exposure to hydrocarbons and, by inference, continuing toxic effects from EVOS, as indicated by elevated cytochrome P4501A [CYP1A] activity (Trust et al 2000; Esler et al 2002; Esler 2008; Esler and Iverson 2010). Based on a weight-of-evidence evaluation from several studies, Wiens et al (2010) concluded no indication of continuing population-level impacts, in terms of either abundance or demographics, on Harlequin Ducks from EVOS.…”

Predicting Impacts of Oil Spills: Can Ecological Science Cope? A Case Study concerning Birds in Environmental Impact Assessments

“…The pigeon guillemot (Cepphus columba) was the only species which is both common during summer and showing consistent declines in overall abundance compared to pre-spill data. Day et al (1995Day et al ( , 1997 used data from the same surveys and analyzed the abundance of 42 species of marine -oriented birds in relation to an oiling gradient. In order to minimize confounding natural variance 26 habitat features of the bays were included in the analysis as well.…”

“…Using a higher alpha value will increase the power of the test. This was the approach used by Day et al (1995) which used alpha levels up to 0.2 in testing the impact of the Exxon Valdez Oil Spill on marine birds (see chapter 3). Mapstone (1995) suggests a procedure for selecting alpha and beta values where a critical effect size is chosen and given primacy.…”

Quantitative Assessment of Current Risks to Harlequin Ducks in Prince William Sound, Alaska, from theExxon ValdezOil Spill

“…Harlequin Ducks are particularly vulnerable to the direct effects of oil spills because they exhibit high site-fidelity and spend most of their time in intertidal and nearshore waters where they feed on epibenthic invertebrates (King and Sanger 1979; Piatt et al . 1990; Day et al 1995, 1997; Holland-Bartels et al . 1998; Esler et al .…”

“…Some studies have reported decreased abundance, linking it to: (1) reduced overwintering survival of females and/or unsuccessful reproduction (Esler et al 2000; Patten et al 2000); (2) degraded habitat quality (Day et al 1995, 1997; Irons et al . 2000; Wiens et al 2004); or (3) exposure to hydrocarbons and, by inference, continuing toxic effects from EVOS, as indicated by elevated cytochrome P4501A [CYP1A] activity (Trust et al 2000; Esler et al 2002; Esler 2008).…”