Although this report focuses on the cumulative effects of anthropogenic stressors, including sound, on marine mammals, recent terrestrial studies have evaluated consequences of noise exposure in ways that have not been thoroughly investigated in marine mammals, such as declines in foraging efficiency (owls and bats ), heightened vigilance (prairie dogs and songbirds ), declines in reproductive success ( Halfwerk et al., 2011), and altered predatorвЂ“prey relationships ( Francis et al., 2009). Sounds from these sources can influence terrestrial and marine animals in similar ways. These include transportation, exploration for and extraction of oil and gas, construction, mining, and military operations. Most of the human activities that produce noise are common to terrestrial and marine ecosystems. Recent estimates suggest that more than 88% of the contiguous United States experiences elevated sound levels due to anthropogenic activities ( Mennitt et al., 2013) and that the propulsion noise from ships elevated ocean sound levels in the 25-50 Hz band by 8-10 decibels (dB) from the mid-1960s to the mid-1990s, which then remained constant or showed a slight decline in the next decade ( Andrew et al., 2011). Worldwide expansion of human activities and infrastructure is increasing the exposure of terrestrial and marine environments to anthropogenic sound ( Hildebrand, 2009 Barber et al., 2010 Shannon et al., 2015). However, the increasing levels of anthropogenic noise create acoustic conditions unprecedented in the evolutionary record ( Swaddle et al., 2015). The world is a cacophony of sounds-from natural sources such as wind-blown vegetation and ocean waves or calling insects, birds, fish, and whales-so all animals have evolved mechanisms to modify their vocalizations to compensate for noise and to focus as listeners on relevant sounds ( Tyack and Janik, 2013). Estimating Exposure and Effects of Sound on Wildlife INTRODUCTION

Predator sound effects