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Quiet ocean experiment

Bioacoustics, Effects of Noise on Wildlife, Ocean, Shipping Comments Off on Quiet ocean experiment

Boston’s WBUR recently interviewed Jesse Ausubel, of Rockefeller University and Woods Hole Oceanographic Institution, about an ambitious project dubbed the Quiet Ocean Experiment.  The idea is to dedicate a year to making detailed observations of wildlife responses to temporary reductions in normally noisy ocean activities, and ideally, to spur a period of several hours to a day during which nearly all human activity in the oceans might cease, in order to see what effect that may have.  Rather than studying the impacts of new noise sources, Ausubel and his colleagues hope to see what removing sound might do.

Here’s a link to a transcript of the five-minute interview.  Or listen below:

New NOAA maps offer compelling picture of ocean noise

Bioacoustics, Ocean, Ocean energy, Science, Shipping, Sonar Comments Off on New NOAA maps offer compelling picture of ocean noise

NOAA noise mapsIn December, NOAA announced the release of the first large-scale ocean noise maps, which have been in development for the past two years.  The Underwater Sound Field Mapping Working Group modeled many sources of sound occurring within 200 miles of the US coast (including ships, seismic surveys, sonar, pile driving, and oil platform decommissioning), as well as modeling shipping noise in full ocean basins (including the Atlantic, pictured at left).  Data  is compiled in several depths and frequency ranges, to account for the full spectrum of various species’ habitat usage and hearing/vocalization ranges.

Dr. Leila Hatch, co-chair of the Working Group, said too many areas of the ocean surface (where sea mammals and whales spend most of their time) are orange in coloration, denoting high average levels. “It’s like downtown Manhattan during the day, only not taking into account the ambulances and the sirens,” she said. “I’d be happier saying it was like a national park.”

Michael Jasny, a senior policy analyst with the Natural Resources Defense Council, which has sued the Navy to reduce sounds that can harm marine mammals, praised the maps as “magnificent” and their depictions of sound pollution as “incredibly disturbing.”

“We’ve been blind to it,” Mr. Jasny said in an interview. “The maps are enabling scientists, regulators and the public to visualize the problem. Once you see the pictures, the serious risk that ocean noise poses to the very fabric of marine life becomes impossible to ignore.”

NOAA has set up a website where this ongoing work will be made available.  In addition, an 85-page report brings together presentations and recommendations from a two-day symposium held last May, at which the Working Group presented their draft results to a couple hundred other experts from agencies, the Navy, oil and gas industry, academia, and nonprofit groups (I was fortunate to be invited to participate in that meeting).

Equally exciting is a companion project by a Cetacean Density and Distribution Mapping Working Group, also introduced at the May symposium, that is working to compile all known studies of whale and dolphin population distribution.  Tens of thousands of cetacean observations are being compiled into month-by-month distribution charts and maps for various ocean regions around the US.  In addition, seasonally biologically important areas (e.g., for breeding, feeding, or mating) are being compiled as part of this work.

The two mapping projects will provide a robust new foundation for assessing the impacts of noise sources, and hopefully to encourage efforts to reduce human noise, especially in biologically important areas.  A New York Times article introducing the noise mapping project includes encouraging words from Michael Bahtiarian, an adviser to the United States delegation to the International Maritime Organization, which is looking at ways to reduce ship noise and vibrations.  “Right now we’re talking about nonbinding guidelines,” he said  “At a minimum, the goal is to stop the increases.”  See earlier AEInews coverage of the IMO efforts from 2008, 2009, and 2012.

SEE ALSO: Detailed ocean noise maps take this approach further in Puget Sound, BC coastal waters 

Ancient whale song: louder than modern human-caused ocean noise?

Bioacoustics, Ocean, Ocean energy, Science, Shipping Comments Off on Ancient whale song: louder than modern human-caused ocean noise?

AEI lay summary:
M.S. Stocker, J.T. Reuterdahl. Is the ocean really getting louder? 164th Meeting of the Acoustical Society of America, Oct. 22-26, 2012.  ASA press release

A paper presented at this fall’s Acoustical Society of America meeting has triggered a wave of provocative headlines about how whale-filled oceans of the past may have been “as loud as a rock concert” or how “Noisy whales made FAR MORE oceanic racket than humans do.”  The paper does indeed ask an innovative question: what was the ocean soundscape like in the pre-whaling days?  And its answer, while couched in a high degree of uncertainty, is also eye and ear-opening: ten times as many whales made a lot more noise than today’s diminished populations, perhaps adding up to overall noise levels that match those caused by today’s shipping, oil and gas exploration, and other human activities in the seas.

It’s probably a bit too acoustics-geeky for me to object to the “rock concert” comparison, but for the record, the paper itself never uses those two words alone or together!  (Though somehow the phrase slipped into the ASA press release; we’ll have to blame the editor or an author’s pre-conference sleep deprivation for the slip…)  In fact, thanks to their differences in density, measurements of sound in water are about 62dB higher than a similar sound level in air; thus, the mention of 126dB of whale sounds filling the ancient oceans would not be equivalent to a rock concert, but more like the 64dB sounds of laughter or a loud conversation.  Which, as it turns out, much better captures the essence of the historic soundscape as described by the authors:

The bio-acoustic environment of the pre-industrial whaling ocean could be correlated to the animal sounds in any biologically diverse and well populated habitat wherein the riot of birdcalls, the stridulation of insects, and the mammal vocalizations are the dominant noise contributors to the soundscape.

The question of ancient ocean sound levels is relevant because much of today’s thinking about the impact of human noise is predicated on research that shows global shipping increasing the ambient noise levels in the oceans by 10dB or more since the 1950’s.  This just happens to be the era in which whale populations were at their nadir, with several species having already become rare enough that it was no longer worth the effort to find and hunt them.  But as the authors stress in their conclusion, an ancient ocean full of whale song — along with the more widespread  sounds of the onomatopoeia-ic large fish, Grunts and Drums, or the “great schools of tuna miles across (that) would churn up the sea surface for days as they migrated past California’s Channel Islands” noted by early 20th century fishermen, which the authors note “would likely be as loud as or louder than even the most tempestuous sea state” — is a very different place than an ocean full of the noise of ship engines and airgun reverberations.

Animals have evolved to fill distinct acoustic niches, with their songs and calls at different frequencies, made at different times or the day or year, and using distinct rhythmic pulses; each species’ hearing is especially tuned, or filtered, to pick out the calls of its own species from the voices of others.  But, as the authors note, “the signature of mechanized ocean noise interference from shipping is broad-band, pervasive, and chronic, and more likely to mask across animal frequency and/or time domain filters throughout large areas of the ocean.”

Or as put so well by Tim Baribeau, it’s important to remember that “we could still be disorienting whales with our bizarre and intrusive industrial sounds. But it’s incredible to think that the oceans may once have been filled with a cacophonous background chatter of animal noise.”

On the water with orca D-tag research crew

Bioacoustics, Effects of Noise on Wildlife, Ocean, Science, Shipping Comments Off on On the water with orca D-tag research crew

Oregon Public Broadcasting recently sent reporter Ashley Ahearn out with the researchers that are listening in on orca activity underwater (covered here last month), and her wonderful, detailed report is now online; check it out!  It includes two videos, one showing a tagged orca’s swimming track, along with every boat in its vicinity over the several hour journey, and the other offering a “poles-eye view” of attaching the D-tag to an orca:

D-TAG study listens to what Puget Sound orcas hear

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OrcapictureBrad Hanson and colleagues at NOAA’s Northwest Fisheries Science Center are currently conducting a second year of exciting new acoustics field research with the Southern Resident killer whales of Puget Sound.  As they did last year, researchers are attaching suction-cup digital acoustic recording tags (DTAGs) to orcas; the tags remain attached for up to four hours, all the while collecting both dive profile data and recording the sound heard (and made) by the animal.  Hanson says that “we’re interested in trying to figure out if the noise levels are interfering with the whale’s ability to communicate effectively during foraging and or actually interferes with their foraging.”

Astonishing bowhead whale song diversity discovered

Bioacoustics, Science 1 Comment »

FramWhen a University of Washington researcher listened to the audio picked up by a recording device that spent a year in the icy waters off the east coast of Greenland, she was stunned at what she heard: whales singing a remarkable variety of songs nearly constantly for five wintertime months.  In a paper just published in the journal Endangered Species Research, and freely available online, Kate Stafford and her co-authors report on acoustic monitoring that took place in the winter of 2008-9 in the Fram Strait, between Greenland and Spitzbergen, a key channel for water circulation between the Arctic and Atlantic Oceans.  

Quite unexpectedly, Stafford found that bowhead whales were singing “almost constantly from the end of November until early March,” with over 60 distinct songs being recorded during these months of deep winter darkness.  It is presumed that these were mating calls, as are the famous humpback whale songs.  However, the researchers stress:

The song diversity noted here is unprecedented for baleen whales. Whether individual singers display 1, multiple, or even all call types, the size of the song repertoire for Spitsbergen bowheads in 2008 to 2009 is remarkable and more closely approaches that of songbirds than other baleen whales.

Also fascinating is the stark difference in types of calls in the two recording locations.  The diverse and continuous singing took place under “a dense canopy of ice cover, (which) may provide a better acoustic habitat for the transmission and reception of song when compared to loose pack ice.” Lead author Kate Stafford notes, “It’s clear there’s a habitat preference. As Arctic sea ice declines, there may be some places like this that are important to protect in order to preserve a breeding ground for the bowhead whales.” 

Download the paper
Read a summary of the work from University of Washington
Listen to a couple of sound samples


Mediterranean fin whales displaced by oil and gas noise

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Ongoing acoustic research in the Mediterranean has confirmed earlier indications that fin whales are far more affected by oil and gas exploration noise than has long been assumed. Manuel Castellote’s most recent paper details a set of disturbing findings, here summarized by the website Science Codex:

Maritime traffic and geophysical exploration –including the search for hydrocarbons– “drastically” reduces the song effectiveness –linked to reproduction and which propagates hundreds of kilometres beneath the Sea– of the whales, which are also the group of marine mammals with the greatest acoustic sensitivity at low frequencies. “The noise generated through human activity in the oceans leads to possible chronic effects on the health of this species”, Castellote states.

After analysing 20,547 hours of recordings of the sounds emitted by the whales, the study published in Biological Conservation indicated that the whales modified the characteristics of their songs in order to try to reduce the impact of noise on their propagation. In addition the researchers recorded a massive displacement of fin whales, triggered by the noise from geophysical prospecting at a distance of 285 km from the study area. “These recurrent displacements, together with the changes in acoustic behaviour, could increase the energy expenditure and reduce the reproductive success of whales affected by the noise”, the expert indicated.

In the long-term the consequences for these mammals are clear: chronic effects which impact on their survival emerge. “Noise in the marine medium, despite being recognised as a significant pollutant, is far from being controlled and regulated within the waters of the Exclusive Economic Zone of Spain”, warns Castellote

Whales can dampen hearing: implications for ocean noise concerns

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You may have noticed a recent flurry of press reports about research in Hawaii that begins to quantify a long-suspected quality of cetacean hearing: the ability to dampen hearing sensitivity so that loud sounds don’t cause damage.  Given the extremely loud volume of many whale calls, which are meant to be heard tens or hundreds of miles away, researchers have long speculated that animals may have ways of protecting their ears from calls made by themselves or nearby whales, perhaps using a muscle response to reduce their hearing sensitivity (not unlike a similar muscular dampening mechanism in humans).  Indeed, earlier studies by Paul Nachtigall’s team had found that some whales could do indeed reduce their auditory response to the sharp clicks they use for echolocation.  In the new study, Nachtigall trained a captive false killer whale named Kina to reduce her hearing sensitivity by repeatedly playing a soft trigger sound followed by a loud sound.  Eventually, she learned to prepare for the loud sound in advance by reducing her hearing sensitivity.  “It’s equivalent to plugging your ears…it’s like a volume control,” according to Nachtigall.

Well, that sounds like a pretty useful trick, given all the concern about human sounds in the sea.  And the media, led by the New York Times, jumped on board with headlines following on the Times‘ assertion that suggested whales  already “are coping with humans’ din” using this method. (Among the exciting headline variations: Whales Can Ignore Human Noise, Whales Learning to Block Out Harmful Human Noise, and UH Scientists: Whales Can Shut Their Ears.)

Oops, they did it again!  Grab some interesting new science and leap to apply a specific finding to a broad public policy question, often, as this time, giving us a false sense of security that the “experts” have solved the problem, so there’s no need to worry our little selves over it any more (as stressed in this NRDC commentary).  To be fair, the Times piece included a few cautionary comments from both scientists and environmental groups, but the headline rippled across the web as the story was picked up by others.

Two key things to keep in mind:  First, this whale was trained to implement her native ability, meant for use with her sounds or those of nearby compatriots, and to apply it to an outside sound made by humans.  This doesn’t mean that untrained whales will do the same.  

And second: If whales can dampen their hearing once a loud sound enters their soundscape, this could indeed help reduce the physiological impact of some loud human sounds, such as air guns or navy sonar. If indeed this ability translates to wild cetaceans, the best we could hope for is that it would minimize hearing damage caused by occasional and unexpected loud, close sounds that repeat.  There would be no protection from the first blast or two, but perhaps some protection from succeeding ones; or, if the sound source was gradually approaching or “ramping up,” as often done with sonar and air guns, animals may be able to “plug their ears” before sounds reach damaging levels, if for some reason they can’t move away.  Even then, the animals are very likely to experience rapidly elevated stress levels, as they would be less able to hear whatever fainter sounds they had been attending to before the intrusion. Yet research in the field suggests that most species of whales and dolphins prefer to keep some distance from such loud noise sources; this hearing-protection trick doesn’t seem to make them happy to hang around loud human sounds.  

Most crucially, these occasional loud sounds are but a small proportion of the human noises whales are trying to cope with. Noise from shipping, oil and gas production activities, offshore construction, and more distant moderate sounds of air guns all fill the ocean with sound, reducing whales’ communication range and listening area, and likely increasing stress levels because of these reductions.  This is the “din” of chronic moderate human noise in the sea, and Kina’s ability would not help her cope with any of it.  We’re a long way from being able to rest easy about our sonic impacts in the oceans.

To end this rant with a bit of credit where due, here’s what may be the more important take-away from the Times article:

Peter Madsen, a professor of marine biology at Aarhus University in Denmark, said he applauded the Hawaiian team for its “elegant study” and the promise of innovative ways of “getting at some of the noise problems.” But he cautioned against letting the discovery slow global efforts to reduce the oceanic roar, which would aid the beleaguered sea mammals more directly.

Floating in whalesong

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Humpback 460x230 fct372x229x52 t325

For a welcome change of pace from stories about contentious acoustic ecology issues, check out this column from Australia about a group of people who were treated to two sessions of whale song while floating near their inflatable raft. Here’s a teaser:

“This time the singer was right before my eyes, and the singing was so powerful you could actually feel it in the water. As I drifted on the surface, the sound vibrated through my body. It was an amazing experience.”

Bernie Krause’s Great Animal Orchestra

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Bernie bookBernie Krause’s new book, The Great Animal Orchestra, is a worthy culmination to his inquisitive career.  After working out a few writerly wrinkles on a couple of earlier books that touched on aspects of his fascination with the world of natural sound, this one offers up a wide-ranging tour of our sounding world, shared in a congenial voice.

This book has rightfully garnered widespread praise, including the coveted cover spot on the NY Times Book Review section, as well as write-ups in The Washington Post, The Ecologist, The San Francisco Chronicle, and Wired. Check each of these out for good, brief glimpses into the stories you’ll find between these covers. The Wired piece is particularly well done, with many sound samples; more sounds can be heard on the site of publisher Little Brown.

Several key themes provide the foundation of the book.  First and foremost is Krause’s segmentation of the soundscape into geophony (sounds of wind and water and other movement of natural objects), biophony (sounds of animals, both vocal and sounds of movement), and anthrophony (sounds of humans, especially mechanical and amplified sounds). Similar divisions are used by bioacousticians, as evidenced in a couple of talks at a recent Bureau of Ocean Energy Management workshop on sound and fish that I attended.  Likewise, Bernie is an eloquent spokesman for the widespread thought that early human music has its roots in a time when tribal peoples considered themselves but one voice in a local sounding landscape; this theme is emphasized in the subtitle to the book, “Finding the Origins of Music in the World’s Wild Places.”

Krause’s reflections on our urbanized relationship to sound are grounded in the soundscape tradition of R. Murray Schaffer, while his continuing efforts to understand the dynamics and relationships in natural soundscapes – using spectrograms to illustrate possible use of acoustic niches (differences in pitch, rhythm, or time of day) that allow a plethora of creatures to each be heard within a complex biophony – are contributions to the leading edges of scientific investigation of soundscape ecology.  Many reviewers note the rambling quality of the book as a small downside, but I found that it brought me as a reader into Bernie’s world, where pure wonder at the diversity of sounds crosses paths with speculative theories, sorrow at what’s disappearing, and a commitment to draw us into a deeper communion with the sounding world that surrounds us. A mindful engagement with sounds, or with the world as it is today, will inevitably bring us to such a mix of thoughts, feelings, and inquiries; this book one of the best invitations into the acoustic aspects of our times.

Ocean noise assessment needs to look past dB, to context of exposure

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A paper recently published in Conservation Biology suggests that current ocean noise regulations are likely not providing sufficient protections against impacts on marine life.  The authors note that current regulations are based on preventing direct physical injury from very close exposure to sound, while considering behavioral impacts to decrease consistently with greater distance, or the “zones of influence” approach to noise impact assessment.  However, some key impacts, such as interruptions in feeding or temporary abandonment of important habitat, are not accounted for.

Rather than fully summarizing the paper here, I’ll turn you over once again to Caitlin Kight of Anthropysis, who has recently been providing excellent coverage of anthropogenic noise issues as part of her larger focus on human impacts in the natural world.  Please see her full post to get the whole story; here’s a teaser:

In a previous study on behavioral responses of marine animals to noise, one of the authors of the current paper found that the “zones-of-influence approach did not reliably predict animal responses.” Furthermore, we know from terrestrial studies that a variety of additional factors–an animal’s past experience and conditioning, current behavioral state, acoustic environment, and type of exposure, to name a few–all affect the extent to which it will be impacted by noise pollution.

…(Studies in terrestrial and ocean environments have shown that) noise can have more subtle, but equally important, effects on wildlife. For instance, abundance and diversity may shift as animals flee from, or learn to avoid, particularly noisy areas; individuals may alter their behaviors in counterproductive or even dangerous ways; and noise may make important acoustic signals difficult to hear, even in the absence of actual deafness. In short, the researchers write, the current marine noise concept “ignores a diverse suite of environmental, biological, and operation factors” that can impact both perception of, and response to, anthropogenic noise. Thus, they argue, it is necessary to overhaul the system and “[incorporate] context into behavioral-response assessment.”

Ellison, W.T., Southall, B.L., Clark, C.W., and Frankel, A.S. 2012. A new context-based approach to assess marine mammal behavioral responses to anthropogenic sounds. Conservation Biology, online advance publication.

Leading scientists call for reducing ocean noise

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NOAA humpback with calf copyTwo of the US’s most widely-respected ocean bioacousticians have called for a concerted research and public policy initiative to reduce ocean noise.  Christopher Clark, senior scientist and director of Cornell’s Bioacoustics Research Program, and Brandon Southall, former director of NOAA’s Ocean Acoustics Program, recently published an opinion piece on CNN that is well worth reading in full.  They stress the emerging scientific awareness that chronic moderate noise from shipping and oil and gas exploration is a more widespread threat to marine life than the rare injuries caused by loud sound sources like sonar.  Here are a couple of teasers:

Today, in much of the Northern Hemisphere, commercial shipping clouds the marine acoustic environment with fog banks of noise, and the near continuous pounding of seismic airguns in search of fossil fuels beneath the seafloor thunder throughout the waters. In the ocean’s very quietest moments, blue whales singing off the Grand Banks of Canada can sometimes be heard more than 1,500 miles away off the coast of Puerto Rico. But on most days, that distance is a mere 50 to 100 miles.

Whales, dolphins and seals use sounds to communicate, navigate, find food and detect predators. The rising level of cumulative noise from energy exploration, offshore development and commercial shipping is a constant disruption on their social networks. For life in today’s ocean, the basic activities that we depend on for our lives on land are being eroded by the increasing amount of human noise beneath the waves.

These stark realities are worrying. But emerging technologies for quantifying and visualizing the effects of noise pollution can help drive a paradigm shift in how we perceive, monitor, manage and mitigate human sounds in the ocean. Ocean noise is a global problem, but the U.S. should step up and lead the way.

Clark and Southall make three specific recommendations: to establish a more comprehensive network of acoustic monitoring stations in order to better understand our overall acoustic footprint in the seas; to encourage and accelerate development of noise-reduction technologies (especially to make ships quieter, and also to develop new technologies for oil and gas exploration and underwater construction that generate less noise); and a shift in federal regulations from avoiding acute injury, toward protecting ocean acoustic habitats and ecosystems.

Fish survey sounds reduce humpback songs 120 miles away?

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AEI lay summary of the following paper:
Risch D, Corkeron PJ, Ellison WT, Van Parijs SM (2012) Changes in Humpback Whale Song Occurrence in Response to an Acoustic Source 200 km Away. PLoS ONE 7(1): e29741. doi:10.1371/journal.pone.0029741
Read or download online (free)

An ongoing research project that monitors whale calls and shipping noise in Stellwagen Bank east of Boston Harbor has reported an unexpected reduction in humpback whale songs during an 11-day period in which their recorders picked up low frequency sounds from a fish-monitoring system 120 miles away.  If this data does indeed represent whales ceasing singing or moving away in response to the distant sonar, this would be the first clear-cut indication that discrete human noise events may affect marine mammal behavior outside the immediate area.  The authors note that these results could suggest that impact assessments need to consider effects at longer ranges, and that effects may occur at received sound levels much lower than those generally considered worthy of concern.  This study simply reports the reduction in singing; any longer-term effect that may have on the animals is unknown (these are not mating calls).

The reduction in songs occurred at a time of year (early fall) when humpback songs are beginning to increase in this area; on years when the fish sonar was not in operation, the numbers of songs steadily increased over the 33-day study period.  But in 2006, when the fish sonar was heard at Stellwagen Bank for 11 days (8 of which included sonar sounds for over 7 hours), the number of minutes per day when humpbacks were singing dropped, some days to zero.  The average (mean) number of hours of whale song dropped from about 75 in the previous 11 days to about 15 minutes during the time the fish sonar was heard, before increasing to close to 3 hours per day once the sonar transmissions ceased.

The figure below shows the data from each of three years.  For each year, there are 33 days of data, with the middle 11 days being the period (Sept. 26-Oct 6) in which the sonar sound occurred in 2006.  The open circles are the mean minutes/day for each 11-day period, with the rectangular boxes representing the upper and lower quartiles of data for each period; black dots represent one or two days in each period in which the calling rates for that day were unusually far outside the range for other days in that period.

Risch 2012 dataWEB

Ed. note: Interpreting the results of vocalization studies is complicated by the fact that there is much variability in vocalizing rates, and response/sensitivity to human noise, from one animal to another; and similarly, in numbers of whales in the area from year to year.  (This acoustic data counts singing minutes, but not animal numbers, which must be monitored visually.)

Read the rest of this entry »

Join citizen science project to ID whale calls

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Over the past few years, new and relatively inexpensive new hydrophone systems have allowed biologists to place autonomous recorders in far more locations, collecting vast amounts of acoustic data that can help them to understand the population dynamics of marine mammals, as well as to monitor interactions and effects of human noise on marine mammal communication.  They’re also looking forward to learning more about individual and pod communication patterns.

But this flood of new data hits a bottleneck when it needs to be assessed by human listeners.  There are several robust automated call detection programs available, but even these must be checked by humans, who can hear similarities in calls or see patterns in the sonograms that present the complex calls as pictures of the frequency patterns.

To the rescue comes a new crowdsourcing project from Scientific American and Zooniverse, WhaleFM.  Individuals from around the world are invited to join the research teams from Woods Hole and the University of St. Andrews by matching new recordings of orcas and pilot whales with  known calls or call types (often associated with particular behaviors). While orca society is moderately well-understood, with many call types already identified, this aspect of pilot whale research is at an earlier stage, and users will help to decide which Pilot Whale calls match, and help in discovering whether the same call is make by one individual, one group, or across broad areas. For more on the project, check the link above, or this blog post from Scientific American.

Moderate noise changes bird communities

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Research summary of Francis, C.D., Ortega, C.P., Cruz, A. 2011. Noise pollution filters bird communities based on vocal frequency. PLoS ONE 6(11):e27052.

An ongoing research project in New Mexico continues to shed more detailed light on the question of how moderate human noise affects nearby wildlife.  In a study design that effectively separates out the impact of the noise from other habitat disruption effects, Clint Francis and his colleagues are finding that some species are displaced, while others seem to thrive in areas with coalbed methane compressor stations creating noise around the clock.  The most recent paper to be published by Francis et al finds that species that sing at lower frequencies are most likely to avoid the noisy areas, while those who vocalize at higher frequencies are more apt to be unaffected or even thrive.

While this research studies an area with oil and gas development noise, it’s likely that similar effects would occur in and near wind farms, which also produce predominantly low-frequency noise. And, as the authors note to conclude their paper: “At the community-level, we must still determine whether noise is an agent of ecological filtering for other taxa that rely on acoustic communication.”

Rather than doing the full AEI lay-summary of the most recent paper, I want to point you to the great summary already written by Caitlin Kight, biologist who studies the effects of anthropogenic disturbances on animals; it was recently featured on her Anthrophysis blog.

David Dunn, the tree whisperer? (great bark beetle story, though!)

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David Dunn is a longtime friend and colleague to AEI here in Santa Fe, and in fact his underwater insect recordings were my first taste of the sounds of the natural world having the potential to be deeply strange and amazing, rather than “just” beautiful. So when he discovered that the bark beetles chewing their way through the piñon pines in the hills of New Mexico were making all sorts of bizarre sounds, and suggested publishing a CD to benefit AEI, I was all for it.

Since then, the bark beetle inquiry has taken on a life of its own, becoming a perfect expression of David’s longtime conviction that artists can contribute in significant ways to science.  The acoustic behavior and communication of bark beetles was previously unstudied by entomologists, and now he’s being called to consult with scientists studying not only the piñon pine beetle, but also the mountain pine beetles ravaging larger higher-elevation and higher-latitude pines, as well as insect pests of the non-beetle persuasion.

This past week, a long article appeared in several Canadian newspapers, providing the most detailed look yet at David’s beetle odyssey.  It’s an excerpt from a new book by Andrew Nikiforuk, Empire of the Beetle: How Human Folly and a Tiny Bug Are Killing North America’s Great Forests.  The article dubs David “the tree whisperer,” though so far he hasn’t quite figured out how to calm the outbreaks; in fact, the research so far seems to be leading more toward driving beetles crazy than calming them.  But after forgiving the headline writer, we can sink into he article itself, which is the most detailed, entertaining version yet of David’s beetle adventures.

The sounds of spring under Arctic Ice

Bioacoustics, Ocean, Science 1 Comment »

The NY Times is hosting a field journal by Kate Stafford of the University of Washington, as she recounts her work as part of a team surveying for bowhead whales along Alaska’s north slope.  This recent post is a marvelous evocation of the soundscape of spring in those northern seas.  You should definitely go read the whole thing (there is an absolutely beautiful extended audio clip of a chorus of bearded seals, bowheads, and belugas, as well as shorter clips of each individually), but here are some teasers:

Beardedseal staffordWEB

You can look across a vast expanse of ice, all white and blue and cold, and see nothing. The lead is choked with pack ice or sealed over with newly formed ice, and there is no movement or sound. With few birds, no whales and no bears, one might mistake the Arctic for a desert. But if you go down to the ice edge, pick a hole in the new ice deep enough to reach water and drop in a hydrophone (an underwater microphone), the cacophony is astonishing.

What I have come to enjoy just as much as listening is passing the headphones to someone who has never heard springtime in the Arctic. It is a rite of spring that would stun even Stravinsky.

Here in the Chukchi Sea the springtime soundscape is dominated, always, by the long trills of male bearded seals….Though we have seen only one or two bearded seals off Barrow, it is clear from the acoustic data that there are many of them trilling all at once and within only a few kilometers of the perch. (the photo, by Kate Stafford, is of one of the bearded seals that showed itself)

The low frequencies used by bowhead whales overlap the acoustic bandwidth in which large ships and oil and gas exploration produce sound. These manmade sources of noise are likely to increase background noise levels as summer sea ice continues to decline and shipping routes cross the Arctic during ice-free summers. It is possible that this increase in noise will affect bowhead whales in particular by causing them to change the frequencies they use to communicate or the duration of the calls they produce, or by restricting the ranges over which they communicate.

Bioacoustics would benefit from shared technology, says new paper

Bioacoustics, Science Comments Off on Bioacoustics would benefit from shared technology, says new paper

Conservation Magazine’s Journal Watch has a nice summary of an important new overview of acoustic monitoring (more at the link):

Computer and electronics revolutions have produced sound-recording gear that is “transforming the way we study individuals and populations of animals, and are leading to significant advances in our understandings of the complex interactions between animals and their habitats,” a multinational team of researchers writes in the Journal of Applied Ecology.

Using arrays that can include dozens of microphones, for instance, researchers have been able to closely track tiny birds through nearly impenetrable tropical undergrowth and map out their territories. And specialized sound-analysis software can even help researchers figure out the species, age, and sex of noisy animals. Acoustic arrays have also enabled scientists to figure out when birds, such as sage grouse and blackbirds, are calling in a particular direction, or when they are sending broader signals.

“The wide-scale application of acoustic recording and processing technology has the potential to transform the fields of ecology, behaviour and conservation biology,” the team writes. But it will take a little innovation – and some sharing — to make the most of the new tools, they add. One “pressing challenge” is developing better signal-processing algorithms; another is developing common technologies that researchers can share – as opposed to the “customized” systems now in use.

To hurdle these obstacles, the authors suggest scientists “set up a website or wiki to serve as a repository for collective experiences and knowledge” – or expand an existing resource, such as the Bioacoustics listserv. Overall, however, they believe “the future for bioacoustic monitoring in the terrestrial environment is bright.”

Blumstein, D., Mennill, D., Clemins, P., Girod, L., Yao, K., Patricelli, G., Deppe, J., Krakauer, A., Clark, C., Cortopassi, K., Hanser, S., McCowan, B., Ali, A., & Kirschel, A. (2011). Acoustic monitoring in terrestrial environments using microphone arrays: applications, technological considerations and prospectus. Journal of Applied Ecology DOI: 10.1111/j.1365-2664.2011.01993.x

Related: See these two recent posts about related work being done by a team of researchers touting a new subdiscipline, soundscape ecology.

NPR covers new “soundscape ecology” research

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Two recent features on NPR looked at (and listened to) new academic research that is being framed as “soundscape ecology.”  Very similar to our work with acoustic ecology, the new discipline aims to be seen as a subset of the established field of landscape ecology, with a focus (naturally!) on the ways soundscapes can inform us about the health of habitats.

The first piece, from last month, was a 5 minute segment on Weekend Edition, with Bryan Pijanowski of Purdue and Jesse Barber of Boise State (who has also worked extensively with National Park Service researchers).  It can be heard (and read) here.

The second piece is close to a half-hour long, and is a conversation with Pijanowski and Bernie Krause of Wild Sanctuary.  It can be seen and heard here.

Humpback whales share seasonal “hit songs”

Bioacoustics, Ocean, Science Comments Off on Humpback whales share seasonal “hit songs”


A ten-year study in the western Pacific has documented the ways that new humpback whale songs move through several distinct populations over the course of a breeding season. “Our findings reveal cultural change on a vast scale,” said Ellen Garland, a graduate student at The University of Queensland. Multiple songs moved like “cultural ripples from one population to another, causing all males to change their song to a new version.” This is the first time that such broad-scale and population-wide cultural exchange has been documented in any species other than humans, she added. (Ed. note: researchers have also suggested that cultural patterns are passed among sperm whale populations)

Once a new song emerges, all the males seem to rapidly change their tune. Those songs generally rise to the “top of the chart” in the course of one breeding season and typically take over by the end of it. “We think this male quest for song novelty is in the hope of being that little bit different and perhaps more attractive to the opposite sex,” she said. “This is then countered by the urge to sing the same tune, by the need to conform.”

More, including whale song audio, here.

Related story: Acoustic recorders reveal new humpback breeding areas in central Pacific.

Human noise can distract animals from predator approaches

Bioacoustics, Ocean, Science Comments Off on Human noise can distract animals from predator approaches

Conservation Magazine highlights a fascinating new study:

A loud motor boat can be annoying. If you are a hermit crab, however, the sound could be deadly. Last year, researchers discovered that playing boat noise distracted the crabs, preventing them from paying attention to potential predators. It’s just one example of how human-created sounds can interfere with “biologically important decisions about food selection, mate selection, and predator detection,” a new review of animal “attention” finds.

The paper reviewed a wide range of research studying attention in many animals, and found that human noise can have either pros or cons for conservation; in some instances, we could use noise to disrupt animals causing habitat disruptions.  Overall, “we need studies that aim to better understand the population consequences of distraction on wildlife populations,” the authors conclude.


Support Kickstart project to send 6 recordists to the Amazon

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Franciso Lopez’s annual 2-week workshop in the Amazon offers field recordists an amazing opportunity to both explore the rainforest, and collaborate, learn, and create with a community of peers.  In recent years, the economic stresses we all feel have made it more difficult for sound artists to raise the funds for this unique experience.

This year, there’s a Kickstarter project going, which if successful will fund 6 artists for the trip, and assure that the program continues.  If you’re not familiar with Kickstarter, it’s an online platform where entrepreneurs, artists, and others raise funds for worthy projects and product development; in return for your donation, you receive some of the fruits of the enterprise.  In this case, recordings!  Pledges are made now, and the project only proceeds if they meet their funding goal, at which point your pledge is paid out.

Let’s make it happen!

Scientists listen to habitats awakening in spring

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US News has a good piece today on Bryan Pijanowski’s research team at Purdue, about how the new field of soundscape ecology may help us to understand ecosystem dynamics and changes.

This April, when you step outside and hear the first sounds of spring, you won’t be hearing just songbirds and buzzing insects, but aural evidence of an awakening ecosystem. The emerging science of soundscape ecology is building on the established field of bioacoustics to create a new way of gauging ecosystem health and diversity—by listening.

“Natural sounds can be used like a canary in a coal mine, as a critical first indicator of environmental changes,” said Bryan Pijanowski, an ecologist at Purdue University in West Lafayette, Ind.

Pijanowski and his colleagues outlined their vision of soundscape ecology in the March issue of BioScience. The new field will take a much broader approach to collecting and evaluating sound than ever before, although the authors caution that no coherent theory yet exists to categorize the ecological significance of all the sounds emanating from a landscape.

Scientists have been using sound as a tool for studying the natural world for some time, mainly through bioacoustics, the study of sounds made by animals. But most of these studies tend to focus on one or two individuals at a time, said Jesse Barber, a sensory ecologist at Boise State University in Idaho, who was not part of Pijanowski’s team.

“Using sound to try to discern something about the ecosystem as a whole is what is novel about soundscape ecology,” Barber said.

Follow the link at the top of this post to read the whole article.

Lonely whale sings in its own frequency

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This story has been floating around for nearly ten years now, but I hadn’t come across it until Treehugger posted on it this week.  Click on over there for their normal rich set of links out to related themes and other sources on this one.

The short version of the story is that there’s a whale, first heard in 1989 and tracked since 1992, that sings at 52Hz, significantly higher than other large baleen whales.  No one else sings at this frequency, and he or she also travels an annual migratory path that misses contact with concentrations of other whales.  Scientists speculate that this animal is either a hybrid of two species, or a remnant of an unknown species.  Either way, it’s a lonely life, calling at a frequency other whales don’t respond to, and may not even hear. The Good website has a link to the sound itself, as well as a podcast that tells more of the story.

Ocean noise importance rises as scientists discover more species that use sound

Bioacoustics, Effects of Noise on Wildlife, Ocean, Science, Shipping Comments Off on Ocean noise importance rises as scientists discover more species that use sound

A new study reveals yet another family of ocean life previously thought to be deaf actually use sound to avoid potentially dangerous areas.  It’s the latest fascinating study from a collaboration between British and Australian scientists that has been revolutionizing our understanding of the role of acoustic ecology in reef habitats. In this study, crustaceans that feed on plankton avoided reef sounds; such reefs are home to fish that would enjoy a crustacean lunch.

CaridMany such small crustaceans are foundations of vast ocean food webs. Co-author Dr Andy Radford, who is leading a major project in Bristol to investigate the impact of anthropogenic noise on marine animals, said: “This highlights just how damaging the impacts of human noise pollution may be for so many different creatures.  Chronic noise from shipping, drilling and mining may mask crucial natural sounds, causing animals to make poor or even fatal decisions, which in turn will threaten vital fisheries and tourism resources.”

Coral reefs are noisy places, and this noise can be an important cue for animal orientation. Dr. Steve Simpson is quoted in a University of Bristol press release: “The combination of clicks, pops, chirps and scrapes produced by resident fish, snapping shrimp, lobsters and urchins can be detected with our hydrophones from many kilometres away.  Our research has already found that reef noise is used by the larvae of fish and even corals to locate and select habitat after their early development in the open ocean, but using noise to avoid reefs, that is a first.”

The mechanism of hearing in these tiny creatures is poorly understood, although co-author Dr Andrew Jeffs and his group from the University of Auckland have found that both tropical and temperate water crabs and lobsters are attracted by the noise of their adult habitat.  Dr Jeffs said: “It is clear that some crustaceans use sounds for orientation, and that noise can induce a downward-swimming response. But this study throws wide open our understanding of crustacean hearing, and much more research is now needed to understand how and what these little critters can hear.”