Assessing the effects of sound on a forest-nesting seabird, the threatened marbled murrelet (Brachyramphus marmoratus)

Abstract

The marbled murrelet is a forest-nesting seabird that is federally listed under the Endangered Species Act. This species is unusual in that it flies up to 70 miles inland to nest in mature trees rather than on shorelines near its foraging habitat. The first nest was not discovered until 1974, and much remains to be learned about this difficult-to-study species, including its basic hearing sensitivities and response to auditory stimuli. In evaluating the effects of federal actions on this species, we must assess the potential effects of anthropogenic sound from a variety of sources, both at-sea and in the forested environment. Over the past ten years, we have developed an approach for analyzing the effect of anthropogenic sound by conducting literature reviews, convening expert panels, and drawing from information on other species. We address both impulsive and continuous sounds from sources including impact pile driving, blasting, heavy equipment noise, and sonar. Interim thresholds for expecting injurious effects from some of these sources are in use, and refinements to our analysis of forest-management activities were recently applied to landscape-scale consultations. The bioacoustic research needs of this unique species continue to emerge as we apply these approaches in both the aquatic and terrestrial environments where murrelets occur.