Megan F McKenna

• PhD
• Researcher at Stanford University

Marine passive acoustic monitoring (PAM) has produced petabytes of data that are used by researchers, resource managers, industry, and regulators to understand how marine animals use sound and the impacts of anthropogenic noise on species and ecosystems throughout the global ocean. These big data provide unprecedented opportunities to study underwa...

Protected areas are typically managed as a network of sites exposed to varying anthropogenic conditions. Managing these networks benefits from monitoring of conditions across sites to help prioritize coordinated efforts. Monitoring marine vessel activity and related underwater radiated noise impacts across a network of protected areas, like the U.S...

The purpose of the United States national park system is to preserve resources unimpaired for the enjoyment of future generations. At Denali National Park (DENA), high levels of air tour traffic and air transportation present challenges to preserving wilderness character. Accordingly, the park attached high priority to measuring visitor impressions...

Marine vessels support diverse ocean economic sectors. As society works towards a sustainable ocean economy, a variety of vessel initiatives are emerging. Passive acoustic monitoring (PAM) offers a method to evaluate these initiatives. Here we review efforts related to vessel noise management in marine protected areas (MPA) and benefits of vessel s...

Passive acoustic monitoring (PAM) data collection has been growing exponentially, resulting in petabytes of data that document ocean soundscapes, how they change over time, and what animals use these ecosystems at varying timescales. Efficiently extracting this critical information and comparing it to other datasets in the context of ecosystem-base...

Protected areas are typically managed as a network of sites exposed to varying anthropogenic conditions. Managing these networks benefits from monitoring of conditions across sites to help prioritize coordinated efforts. Monitoring marine vessel activity and related underwater noise impacts across a network of protected areas, like the U.S. Nationa...

Anthropogenic noise sources impact ecological processes by altering wildlife behavior and interactions with cascading impacts on community structure. The distribution and magnitude of such noise has grown exponentially over the past century, and now inundates even remote areas. Here we investigate biological responses to prolific, anthropogenic noi...

Marine soundscapes provide the opportunity to non-invasively learn about, monitor, and conserve ecosystems. Some fishes produce sound in chorus, often in association with mating, and there is much to learn about fish choruses and the species producing them. Manually analyzing years of acoustic data is increasingly unfeasible, and is especially chal...

Animal migration plays a central role in many ecological and evolutionary processes, yet migratory populations worldwide are increasingly threatened. Adjusting migration timing to match ecosystem phenology is key to survival in dynamic and changing ecosystems, especially in an era of human-induced rapid environmental change. Social cues are increas...

Forest management strategies that create spatially diverse fire-caused disturbance outcomes, consistent with historic fire regimes, are a desired condition for fire adapted western United States forests. In this context, the temporal dynamics of forest response to fire can inform the tempo and scale of forest management, including prescribed burnin...

Matching the timing of life‐history transitions with ecosystem phenology is critical for the survival of many species, especially those undertaking long‐distance migrations. As a result, whether and how migratory populations adjust timing of life‐history transitions in response to environmental variability are important questions in ecology and con...

Chronic low-frequency noise from commercial shipping is a worldwide threat to marine animals that rely on sound for essential life functions. Although the U.S. National Oceanic and Atmospheric Administration recognizes the potential negative impacts of shipping noise in marine environments, there are currently no standard metrics to monitor and qua...

The breeding phenology of wood frogs (Lithobates sylvaticus) in subarctic ecosystems is closely tied to the weather conditions at the onset of spring. With climate change occurring at an accelerated rate at high latitudes, we expect changes in the timing of the onset of spring to impact the timing of wood frog breeding. Wood frogs in the subarctic...

A cost-efficient approach to long-term monitoring is to focus on one species or group of organisms as indicators of ecological condition. Through the use of autonomous monitoring technologies, monitoring programs can efficiently expand the biological community surveyed and inferences made. Amphibians have been monitored in Yellowstone and Grand Tet...

1.Matching the timing of life history transitions with ecosystem phenology is critical for the survival of many species, especially those undertaking long-distance migrations. As a result, whether and how migratory populations adjust timing of life history transitions in response to environmental variability are important questions in ecology and c...

Soundscapes offer rich descriptions of composite acoustic environments. Characterizing marine soundscapes simply through sound levels results in incomplete descriptions, limits the understanding of unique features, and impedes meaningful comparisons. Sources that contribute to sound level metrics shift in time and space with changes in biological p...

Rapid changes in the Arctic from shifting climate and human use patterns are affecting previously reported distributions and movements of marine mammals. The underwater soundscape, a key component of marine mammal habitats, is also changing. This study integrates acoustic data, collected at a site in the northern Bering Sea, with information on sou...

Soundscapes are promising indicators of marine habitat condition, yet this approach remains untested in many ecosystems, and soundscape-ecological relationships remain unclear. In this study, we analyzed soundscapes in kelp forest habitats off the coast of California, USA, in Channel Islands National Park. We investigated if (1) soundscape features...

Linking individual and population scales is fundamental to many concepts in ecology [1], including migration [2, 3]. This behavior is a critical [4] yet increasingly threatened [5] part of the life history of diverse organisms. Research on migratory behavior is constrained by observational scale [2], limiting ecological understanding and precise ma...

Aircraft noise is pervasive across the United States, including national parks, but its effect on wildlife are unresolved. As with other noise sources, aircraft noise may affect species physiology and behaviour by being perceived as a threat, distracting individuals, or degrading the sensory environment. This study aimed to understand the effect of...

Passive acoustic monitoring of ocean soundscapes can provide information on ecosystem status for those tasked with protecting marine resources. In 2015, the National Oceanic and Atmospheric Administration (NOAA) established a long-term, continuous, low-frequency (10 Hz–2 kHz) passive acoustic monitoring site in the Cordell Bank National Marine Sanc...

ContextNatural sound and light regulate fundamental biological processes and are central to visitor experience in protected areas. As such, anthropogenic light and noise have negative effects on both wildlife and humans. While prior studies have examined the distribution and levels of light or noise, joint analyses are rarely undertaken despite the...

Global expansion of human activities is associated with the introduction of novel stimuli, such as anthropogenic noise, artificial lights and chemical agents. Progress in documenting the ecological effects of sensory pollutants is weakened by sparse knowledge of the mechanisms underlying these effects. This severely limits our capacity to devise mi...

Increasing anthropogenic noise is having a global impact on wildlife, particularly due to the masking of crucial acoustical communication. However, there have been few studies examining the impacts of noise exposure on communication in free-ranging terrestrial mammals. We studied alarm calls of black-tailed prairie dogs (Cynomys ludovicianus) acros...

Various sounds in nature shape how animals, including humans, interact with their environment.

The article Alarm call modification by prairie dogs in the presence of juveniles

Despite efforts to aid recovery, Eastern North Pacific blue whales faces numerous anthropogenic threats. These include behavioral disturbances and noise interference with communication, but also direct physical harm – notably injury and mortality from ship strikes. Factors leading to ship strikes are poorly understood, with virtually nothing known...

Roads are a pervasive feature across the U.S., and traffic and its associated noise has significant impacts on wildlife. However, we know little about the effect of motorcycle traffic and the potential for prolonged response of animals to loud and periodic traffic disturbances. We studied the behavioral response of multiple species in Devils Tower...

In an era of unprecedented environmental change, US national parks are refuges of natural ecosystems and facilitate connections between humans and nature. However, anthropogenic noise is an increasingly pervasive threat in these parks. To diagnose noise levels and sources, we analyzed thousands of hours of acoustic recordings collected across park...

No PDF available ABSTRACT Soundscapes are comprised of chronic and transient sounds that overlap each other in time and frequency. These sound sources can be of anthropogenic, geological or biological origin. We automatically discriminated and classified sources with an unsupervised learning strategy based on clustering and subsequent training of a...

We present guidance we have developed and adapted through attempts to synthesize and distill the diverse literature documenting wildlife responses to noise into concise support for conservation planning. Our systematic review revealed significant inconsistencies in the use of—and specifications for—acoustic metrics. Studies typically report noise l...

Passive acoustic sensors provide a cost-effective tool for monitoring marine environments. Documenting acoustic conditions among habitats can provide insights into temporal changes in ecosystem composition and anthropogenic impacts. Agencies tasked with safeguarding marine protected areas, such as the U.S. National Park Service and U.S. National Oc...

See "The Many Faces of Soundscapes" on Page 6.

While several drivers of wildlife alarm calls have been identified, recent work on the impact of the audience on the plasticity of alarm calling indicates that intraspecific communication can drive this behavior. We build on this literature by assessing changes in call characteristics in black-tailed prairie dogs (Cynomys ludovicianus) in the prese...

Acoustic communication is an important aspect of reproductive, foraging and social behaviours for many marine species. Northeast Pacific blue whales (Balaenoptera musculus) produce three different call types—A, B and D calls. All may be produced as singular calls, but A and B calls also occur in phrases to form songs. To evaluate the behavioural co...

The National Oceanic and Atmospheric Administration (NOAA)/National Park Service (NPS) Ocean Noise Reference Station (NRS) Network is an array of currently twelve calibrated autonomous passive acoustic recorders. The first NRS was deployed in June 2014, and eleven additional stations were added to the network during the following two years. The twe...

U. S. National Parks are justly celebrated for the superlative quality of their scenic and cultural resources. The Grand Canyon Enlargement Act of 1975 identified natural quiet as an important resource and value. These considerations are two motivations for extensive monitoring of acoustic environments in national park units, and development of mod...

We introduce the open-source Sound Mapping Tools (SMT, implemented in ArcGIS with the Spatial Analyst extension) for use in terrestrial outdoor sound propagation modeling. SMT includes three sound propagation models: an updated version of SPreAD-GIS, based on the System for Prediction of Acoustic Detectability model; NMSIMGIS, a GIS implementation...

Passive acoustic monitoring has the potential to be a powerful approach for assessing biodiversity across large spatial and temporal scales. However, extracting meaningful information from recordings can be prohibitively time consuming. Acoustic indices offer a relatively rapid method for processing acoustic data and are increasingly used to charac...

Anthropogenic noise threatens ecological systems, including the cultural and biodiversity resources in protected areas. Using continental-scale sound models, we found that anthropogenic noise doubled background sound levels in 63% of U.S. protected area units and caused a 10-fold or greater increase in 21%, surpassing levels known to interfere with...

Acoustic recordings have the potential to address a suite of important conservation questions, from assessing phenology shifts due to climate change, to examining the impact of anthropogenic noise on wildlife, to monitoring biodiversity at enormous spatio-temporal scales. However, consistent methods are required to extract meaningful information fr...

Exposure to park visitors can disrupt animal behavior. Management strategies often aim to eliminate direct human disturbance; however, elevated visitor noise levels may remain. Coastal seabird colonies frequently overlap with scenic locations, resulting in high visitor noise and potentially altered behavior, habitat use, and fitness. We examine the...

This study investigates how noise reduction (road closure) mitigates the effect of traffic noise on the acoustic communication of the Eastern wood pewee (Contopus virens) (EAWP), a suboscine passerine. Songs were passively recorded at sites where the traffic pattern of the nearest road was either relatively constant or reduced on a weekly basis dur...

ABSTRACT: Diverse biological consequences of noise exposure are documented by an extensive literature. Unfortunately, the aggregate value of this literature is compromised by inconsistencies in noise measurements and incomplete descriptions of metrics. These studies commonly report the noise level (in decibels, dB) at which a response was measured....

Global increases in environmental noise levels – arising from expansion of human populations, transportation networks, and resource extraction – have catalysed a recent surge of research into the effects of noise on wildlife. Synthesising a coherent understanding of the biological consequences of noise from this literature is challenging. Taxonomic...

Global increases in environmental noise levels arising from expansion ofhuman populations, transportation networks, and resource extraction have catalysed a recent surge of research into the effects of noise on wildlife. Synthesising a coherent understanding of the biological consequences of noise from this literature is challenging. Taxonomic grou...

Appendix S1. Band‐limited energy detector specifications. Appendix S2. Finer resolution ACI calculations. Appendix S3. Dawn chorus spectrogram example.

Monitoring patterns in biodiversity and phenology have become increasingly important given accelerating levels of anthropogenic change. Long-term monitoring programs have reported earlier occurrence of spring activity, reflecting species response to climate change. Although tracking shifts in spring migration represents a valuable approach to monit...

Potential responses of marine mammals to anthropogenic underwater sound are usually assessed by researchers and regulators on the basis of exposure to a single, relatively loud sound source. However, marine mammals typically receive sounds from multiple, dynamic sources. We developed a method to aggregate modeled sounds from multiple sources and es...

Human-made noise in wilderness degrades the quality of wilderness by interfering with natural sounds—a key attribute of wilderness. Commercial air tour overflights are a noise source of particular concern to the US National Park Service. To characterize noise from air tours in wilderness, we developed an assessment framework to guide the decisionma...

Monitoring at more than 600 sites in National Park Service (NPS) units has shown that noise poses widespread concerns: a contaminant to the physical environment, an infringement on superlative visitor experience, and a sensory burden for wildlife. NPS acoustical data were generalized into maps predicting sound levels for the coterminous U.S. These...

Low-frequency noise that is part of the acoustic environment for baleen whales has increased in many areas of the Northeast Pacific Ocean that contain whale habitat. We conducted a spatially explicit risk assessment of noise from commercial shipping to blue, fin, and humpback whale habitats in Southern California waters and explored how noise is af...

There are no standards for assessment of the cumulative effects of underwater sound. Quantitative assessments typically consider a single source, whereas qualitative assessments may include multiple sources but rarely identify response variables. As a step toward understanding the cumulative effects of underwater sound, we assessed the aggregated s...

In this talk, we introduce a method that exploits geospatial data to assess the spatially varying health of marine ecological communities and degree of human activity. Noise from shipping, energy development, and other human activity has become a significant component of marine soundscapes, resulting in changes to or loss of habitat and biodiversit...

Collisions between ships and whales are reported throughout the world's oceans. For some endangered whale populations, ship strikes are a major threat to survival and recovery. Factors known to affect the incidence and severity of collisions include spatial co-occurrence of ships and whales, hydrodynamic forces around ships, and ship speed. Less un...

Type 1 sound level measurements and continuous audio recordings were obtained from two sites near the Mesa Wind Project Site (MWPS), 100 m and 1500 m from the nearest turbine. The sites were upwind of the turbines. Unexpectedly, MWPS ceased operating 29 days after this project began; data were collected for an additional 127 days. Contrasts in hour...

While visual forms of vigilance behavior and their relationship with predation risk have been broadly examined, animals also employ other vigilance modalities such as auditory vigilance by listening for the acoustic cues of predators. Similar to the tradeoffs associated with visual vigilance, auditory behavior potentially structures the energy budg...

Because many wildlife habitats, geological processes, and anthropogenic impacts occur on a regional scale, acoustical analyses must encompass a similar extent. Geospatial sound modeling incorporates spatial representations of biological, geophysical, climatic, and anthropogenic factors to assess expected contributions to the existing sound pressure...

The Natural Sounds and Night Skies Division of the U.S. National Park Service has collected month-long acoustic recordings at more than 300 sites in 73 park units located throughout the United States, dating back to 2000. Each monitoring session lasted 25 days or more; some sites were monitored more than once. At all sites a calibrated Sound Level...

Mid-frequency military (1-10 kHz) sonars have been associated with lethal mass strandings of deep-diving toothed whales, but the effects on endangered baleen whale species are virtually unknown. Here, we used controlled exposure experiments with simulated military sonar and other mid-frequency sounds to measure behavioural responses of tagged blue...

Low-frequency ocean ambient noise is dominated by noise from commercial ships, yet understanding how individual ships contribute deserves further investigation. This study develops and evaluates statistical models of container ship noise in relation to design characteristics, operational conditions, and oceanographic settings. Five-hundred ship pas...

Dataset 1

Marine spatial planning provides a comprehensive framework for managing multiple uses of the marine environment and has the potential to minimize environmental impacts and reduce conflicts among users. Spatially explicit assessments of the risks to key marine species from human activities are a requirement of marine spatial planning. We assessed th...

Singing in a Crowded Ocean: Acoustic Adaptations of Great Whales and Human Impacts Megan F McKenna, National Park Service- Natural Sounds and Night Skies Division Sound plays an important role in both aquatic and terrestrial ecosystems making the acoustic environment a key habitat characteristic that has often been ignored. Animals use sound for a...

For many marine organisms, especially large whales that cannot be studied in laboratory settings, our ability to obtain basic behavioral and physiological data is limited, because these organisms occupy offshore habitats and spend a majority of their time underwater. A class of multisensor, suction-cup-attached archival tags has revolutionized the...

Collisions between ships and whales are an increasing concern for endangered large whale species. After an unusually high number of blue whales (Balaenoptera musculus) were fatally struck in 2007 off the coast of southern California, federal agencies implemented a voluntary conservation program to reduce the likelihood of ship-strikes in the region...

Toothed whales (crown Odontoceti) are unique among mammals in their ability to echolocate underwater, using specialized tissue structures. The melon, a structure composed of fat and connective tissue, is an important component in the production of an echolocation beam; it is known to focus high frequency, short duration echolocation clicks. Here, w...

Simultaneous long-term monitoring of underwater sound and ship traffic provided an opportunity to study how low-frequency noise correlated with ocean-based commercial shipping trends. Between 2007 and 2010 changes in regional shipping off southern California occurred as a consequence of economic and regulatory events. Underwater average noise level...

1. Diving capacity generally increases with body size both within and among taxanomic groups because of the differential scaling between body oxygen stores and metabolic rate. 2. Despite being some of the largest animals of all time, rorqual whales exhibit very short dive times relative to other large divers because of the high energetic costs incu...

Underwater radiated noise measurements for seven types of modern commercial ships during normal operating conditions are presented. Calibrated acoustic data (<1000 Hz) from an autonomous seafloor-mounted acoustic recorder were combined with ship passage information from the Automatic Identification System. This approach allowed for detailed measure...

For the purposes of describing and understanding ambient sea noise for frequencies below about 300 Hz, most of the world's seas can be classified as belonging to one of three bathymetric domains. These domains are distinguished by their proximity to shipping lanes and by the degree to which they are exposed to noises originating at long distances....

Underwater ambient noise levels measured off the coast of southern California were correlated with regional changes in commercial shipping trade. Between 2007 and 2010, two events occurred that resulted in a decrease in ship traffic in the Santa Barbara Channel: the economic recession and a coastal air-quality improvement rule. From October 2005 to...

The extent to which low-frequency noise from large vessels is a part of the coastal marine environment and the ramifications of this for blue whale (Balaenoptera musculus) communication ranges and vocal behavior was investigated in the Santa Barbara Channel (SBC), a region off the coast of southern California. Analysis of noise from individual ship...

There is mounting concern over the effect of ship noise on marine mammals; however, limited empirical data quantifying this noise impede our ability to evaluate impacts. An opportunistic approach for measuring radiated ship noise (20–1000 Hz) was used in this study. Calibrated acoustic data were combined with archived information on seven types of...

Bioacoustic probes were deployed on blue whales in and around commercial shipping lanes in Southern California. The proximity of shipping routes to predictable blue whale feeding grounds makes this an ideal location to study the impact of intense low‐frequency noise on whale behavior. The bioacoustic probe is outfitted with a calibrated hydrophone,...

The relationship between beaked whales and certain anthropogenic sounds remains poorly understood and of great interest. Although Cuvier’s beaked whales (Ziphius cavirostris) are widely distributed, little is known of their behavior and population structure throughout much of their range. We conducted a series of five combined visual-acoustic marin...

This study uses remote imaging technology to quantify, compare, and contrast the cephalic anatomy between a neonate female and a young adult male Cuvier's beaked whale. Primary results reveal details of anatomic geometry with implications for acoustic function and diving. Specifically, we describe the juxtaposition of the large pterygoid sinuses, a...

Postmortem changes in geometry, density, and sound speed within organs and tissues (melon, bone, blubber, and mandibular fat) of the dolphin head were evaluated using computed tomography (CT) scans of live and postmortem bottlenose dolphins (Tursiops truncatus). Specimens were classified into three different treatment groups: live, recently dead, a...

Coastal phytoplankton communities may be significantly affected by breaking internal and surface gravity waves. For example, internal surges have been implicated in cross-shore transport, and rip currents (generated in the surf zone by breaking surface waves) are associated with mixing of water and organisms between the surf zone and the inner shel...

An experiment was conducted to investigate the sound pressure patterns on the melon of odontocetes by using four broadband hydrophones embedded in suction cups to measure echolocation signals on the surface of the forehead of two harbor porpoises (Phocoena phocoena). It has long been hypothesized that the special lipids found in the melon of odonto...