Several recent studies highlight the heightened risks of increased Arctic shipping, along with some opportunities to minimize the effects of shipping noise on specific Arctic species and populations.

With the retreat of sea ice, both the Northwest Passage (along Canada’s northern coast) and the Northern Sea Route (along Russia’s northern coast) are seeing increases in commercial and fishing vessel traffic. While the first cruise ship crossed the Northwest Passage in 2016, Russia’s Northern Sea Route is the current center of activity, with both container ships and LNG (natural gas) tankers making pioneering transits without icebreakers over the past two summers.  Total ship numbers are still modest, as it’s not yet cheaper than the longer route through the Suez canal, but these test runs are explicitly intended to chart the course for rapid increases in the coming years; Russia aims to ship 80 million tons of cargo by 2024, up from 10 million tons in 2017 and 2018, and China is moving rapidly to implement a “Polar Silk Road” initiative to encourage companies to build the infrastructure necessary to ramp up this shortcut to European markets.

Two recent studies address key questions about the biological impact of increased shipping on Arctic ecosystems.  The first, from researchers at the University of Washington and the University of Alaska at Fairbanks, examined the ranges of 80 localized subpopulations of seven key Arctic species, and found that just over half (42) of these would hear increased shipping noise.  Of these, some species are more vulnerable than others:

“Narwhals have all the traits that make them vulnerable to vessel disturbances — they stick to really specific areas, they’re pretty inflexible in where they spend the summer, they live in only about a quarter of the Arctic, and they’re smack dab in the middle of shipping routes,” said co-author Kristin Laidre, a polar scientist at UW Applied Physics Laboratory’s Polar Science Center. “They also rely on sound, and are notoriously skittish and sensitive to any kind of disturbance.”

In addition to narwhals, beluga and bowhead whales and some subpopulations of walrus are likely to be vulnerable to increased noise; ringed and bearded seals, as well as polar bears, will be less vulnerable, thanks to widespread populations and spending much of the summer on land rather than in the water.  In addition, the researchers stressed that the Bering Strait is a key chokepoint for both Arctic sea routes, as well as being a crucial migratory corridor.

“I think we can learn a lot from areas that have already been thinking about these kinds of conflicts between ships and marine mammal populations — for example the North Atlantic right whale, or fin and blue whales around California,” Laidre said. “We could aim to develop some mitigation strategies in the Arctic that help ships avoid key habitats, adjust their timing taking into account the migration of animals, make efforts to minimize sound disturbance, or in general help ships detect and deviate from animals.”

A second study took a different tack, looking at whether speed reductions (as implemented in some areas around busy ports) would reduce the noise impacts.  They used an increasingly common metric, “listening space,” the area or volume of water within which an animal can hear its brethren, its prey, or other biologically important sounds. The researchers modeled ship noise in several key chokepoints on the Northwest Passage, calculating the distance over which vessels sounds would impact the listening space for several species, and at how much the effect could be moderated if the ships were slowed in key areas.  And indeed, the effects were significant:

Under quiet conditions, beluga whales experienced a 50 percent listening space loss when they were 7 to 14 kilometers (4.3 to 8.7 miles) away from a ship traveling at 25 knots. When ships slowed to 15 knots, whales could get as close as 2 to 4 kilometers before they experienced the same loss of listening space.

In other words, when a ship was going faster, the area over which it cut a beluga’s listening space in half might be more than three times larger. This difference is important because there are many places where whales cannot distance themselves from ships in the Arctic (in the narrow Prince of Wales Strait, animals can maintain a maximum distance of just 7 to 10 kilometers).

As always, the results are not all as simple as that; the researchers found that for some species, the effects are less in certain weather conditions or for different kinds of ships (container vs. cruise), and that in some situations, the effects can actually cover a larger area when ambient noise is high (as it increasingly is with loss of ice cover). And, as always with vessel-slowing programs, planners must consider the tradeoffs between moderating the noise level and increasing the time during which ships are audible during slower passages.

With the inevitable increase in Arctic shipping, it will be crucial for both governmental and commercial players take steps to minimize the acoustic impacts in these remote waters, among the last areas in the seas where human noise intrusions have been relatively modest.

Bioacousticians and marine advocates have been closely following plans for the Northern Gateway pipeline in British Columbia, which would greatly increase ship traffic in some coastal waterways that are relatively quiet so far; see previous AEInews coverage.  But another pipeline project, farther along in the permitting process, could push the already stressed waters of southern BC and northern Washington to the acoustic breaking point.  The Trans Mountain Pipeline, built in 1953 and expanded several times since then, is gearing up to nearly triple its capacity and make adaptations that will allow heavy tar sands oil to be moved to the Pacific coast for shipment to Asia.

The expanded Trans Mountain Pipeline would have 75% of the capacity of the proposed Keystone KL pipeline to the Gulf of Mexico, so it has triggered active resistance on similar climate change grounds as Keystone.  At the same time, ocean advocates are stressing the cumulative impact of the additional 720 tanker transits that would occur in already-busy waters that include critical habitats for killer whales, sea lions, and other species.  At this point, most of the additional capacity is targeted for Burnaby, BC (increasing monthly tanker arrivals from 5 to 34), though the pipeline also serves terminals in northern Washington state. (Some of the current capacity is refined and used in North America, but virtually all of the increased capacity will be shipped overseas; thus the tanker traffic will increase 7-fold despite the smaller capacity increase.)

The Canadian Department of Fisheries and Oceans has just released a review of the Trans Mountain proposal, which is currently being considered by the National Energy Board (NEB), and finds it lacking, saying it contains “insufficient information” to adequately assess the threats posed both by underwater noise and ship strikes. “The assessment considers noise from a single project-related ship, without taking into account the additive and cumulative effects of existing noise,” Fisheries and Oceans Canada concludes.

Marine advocates second that concern.  Margot Venton, a staff lawyer with Ecojustice, stresses that “The critical habitat is basically as noisy as it can be. We need to make it quieter.” Misty MacDuffee, a fisheries ecologist with Raincoast Conservation Foundation, said anything that impedes the ability of whales to feed is a serious concern. “It’s just the growing din,” she said. “They are trying to [communicate and hunt] in an increasingly loud environment.” (Thanks to the Globe and Mail for their coverage and all these quotes.)

The NEB review is slated to be concluded by July; the federal government will then take six months to consider the NEB’s recommendation and make a final decision.  If approved, construction could begin in 2016 and be completed the following year.

UPDATE, 7/14/16: The NEB has recommended that the pipeline be approved, despite the likelihood that additional ship traffic will saturate the acoustic environment to the point that ship noise is present in some areas nearly 100% of the time (currently 85%).  Transmountain will need to meet 157 conditions, but they’re confident that will be achievable.  The final stage of the approval process is a final decision from the Canadian government, which is expected by the end of this year.

AEI lay summary of:
Daniel E. Holt, Carol E. Johnston. Traffic noise masks acoustic signals of freshwater stream fish. Biological Conservation 187 (2015) 27-33 (ScienceDirect link)
With each passing year, we learn more about the ways that animals use sound—and so also how human noise interferes with their lives.  A new paper looks at how traffic noise from bridges may impinge on the mating calls of freshwater fish; this is the first study to use some of the new metrics of “communication space” in these important and widespread habitats. The species studied was the blacktail shiner, a member of the largest family of fishes (including carps and minnows), with the study sites being small streams passing under bridges on I-85 in Alabama (image shows one of six sites).

Male shiners make two sounds during mating: loud “knocks” used to challenge other males who are intruding, and softer “growls” used to court females.  Streams are naturally loud environments, with noise from wind, rain, and turbulence; shiners take advantage of a relatively quiet “window” in the broadband noise, between 172 and 366Hz (like many other animals that vocalize in frequency ranges less cluttered by local sounds or other species).  While the traffic noise is not much louder than the natural stream sounds at frequencies above 700Hz, unfortunately for the shiners, in this key quiet window it is significantly louder than the stream noise—and also the seductive growls of male shiners.  The graph shows natural ambient noise (green), road noise (red), and growls (black dotted line).  The two peaks in the growl acoustic spectrum are particularly important; the lower peak in particular is dramatically drowned out by traffic noise.

The bottom line for the fish is that their knocks, which can be heard above the natural sounds of the creek out to about a half meter, are just slightly masked—only within three meters of the bridge are they lost in road noise (3m is the mean; maximum modeled range of effect is 22m).  So these calls of challenge and defense among males, which may also show females who’s the most fit, can serve their purpose unless the action is taking place right under a bridge.  The subtler sounds of the growls, however, are much more impacted.  These sounds, being quieter, are meant to be heard at very close range (generally just a few inches from the nest sites); yet the lower peak in the growl sound spectrum will be effectively inaudible in areas out to 640m (almost a half mile) from a bridge, and the second peak will be similarly masked out to 40m (both distances are means; maximum ranges are, respectively, 12km/7 miles and 1600m/1 mile). Adding insult to injury, peak spawning time is morning, before water temperatures rise, which may coincide with peak morning traffic.  Of course, only a small portion of most spawning streams is near heavily travelled interstates or secondary roads; those near more sporadically-travelled local roads are likely to be less affected.  Still, if the effect extends a half mile or more, large stretches of many streams could have some degradation of their natural and necessary acoustic habitat.

The authors’ conclusion neatly sums up what all this means going forward:

AEI lay summary of four recent papers:
Simpson SD, Purser J, Radford AN (2014). Anthropogenic noise compromises antipredator behavior in European eels. Global Change Biology (2014), doi: 10.1111/gcb.12685
Voellmy IK, Purser J, Simpson SD, Radford AN (2014). Increased Noise Levels Have Different Impacts on the Anti-Predator Behaviour of Two Sympatric Fish Species. PLoS ONE 9(7): e102946. doi:10.1371/journal.pone.0102946
Nedelec SL, Radford AN, Simpson SD, Nedelec B, Lecchini D, Mills SC (2014). Anthropogenic noise playback impairs embryonic development and increases mortality in a marine invertebrate. Sci. Rep. 4, 5891; DOI:10.1038/srep05891 (2014).
Erica Staaterman, Claire B. Paris, Andrew S. Krough (2014). First evidence of fish larvae producing sounds. Biol. Lett. 2014 10, 20140643.

It used to be that most concern about human noise and ocean life was centered on whales and the two loudest sound sources: sonar and seismic surveys.  But in recent years, we’ve seen a growing wave of studies looking at how chronic, moderate ship noise can interfere with normal behavior and development of other creatures, including squid, fish, crustaceans, and other “lower” species.  Four recent studies add to the list of known or suspected ways that shipping and recreational boat noise may be wreaking previously unsuspected havoc throughout the oceanic web of life.

The most dramatic results came in a study of eels’ responses to predators (above). When exposed to ship noise, only half as many eels responded to an ambush attack from a predator (just 38% reacted, down from 80%); and, those that did react did so 25% slower than normal. Likewise, researchers tested eels’ ability to detect a “pursuit” predator that follows the eels before attacking; in this case, the eels in ship noise were caught twice as quickly.  Looking deeper, the researchers examined how noise affects metabolic rates, stress, and breathing rates, and an interesting feature of eel life, the preference for using one side of their body when interacting with other eels and when hunting.  The researchers explain:

“In the same way we write using our right or left hands, fish have a preferred side to approach a predator or to stay next to shoal mates with. We watched each eel as it explored a maze in ambient conditions to classify its right or left bias, then we exposed half to ship noise and half to more ambient noise. Their preferences went away when they were exposed,” says Dr Steve Simpson of the University of Exeter, lead researcher on the study. The team suspect this means ship noise affects eels’ cognitive processes, which could mean other processes, like learning, may also be affected. Alongside raised metabolic and ventilation rates, the scientists note the stress being caused by the shipping noise is similar to the levels fish exhibit in ocean acidification studies.

“We know shipping isn’t going to stop, but we can do things like move a shipping lane so it doesn’t interact with the migrations paths of animals,” Simpson suggests. “It’s a pollutant we have more control over than something like atmospheric carbon dioxide. These animals are having to deal with all the stressors globally, so if we can alleviate just one it might give the animals more resilience to other stressors like ocean acidification, which will come later.”

A study of two species of small fish highlights species differences and the ways that noise can alter behavior in unexpected ways.  Here, one species of fish exposed to ship noise actually responded more quickly to the presence of a predator,

Read the rest of this entry »

We’ve all heard that humpback whale songs have complex, repeating structures, and that the themes evolve over course of months and years. Yet listening to the gruts, guffaws, and groans of humpback recordings, it’s hard for most of us to really hear the large-scale structure that ties together these deeply alien sounds. In an article recently published on Medium David Rothenberg and Mike Deal have built on work done back in the 1970s by Scott McVay, and created a visual representation for humpback songs that makes it all suddenly and delightfully clear.

For starters, Deal created glyphs to represent particular “song units.” Each of these distinctive utterances is shown in a different color; the shapes mimic the shape of the sonogram of the sound. Following on McVay’s work with Roger and Katie Payne, Deal and Rothernberg show how these units are combined to create “phrases” lasting 20-40 seconds; several phrases create a “theme,” and a sequence of themes lasting 5-30 minutes is the “song.” Deal and Rothenberg take McVay’s work one step further by overlaying the units on an expanded musical staff to represent the frequqency of each phrase (each utterance of the whales includes a broad range of tones, like a chord with many audible overtones, so the glyphs stretch over a substantial span of the musical staff).

Finally, they present full songs in this new notational language:

As Rothenberg notes, “The pattern in the phrases starts to seem like an alien language. But even eerier is how much more human-like the order appears than most known animal vocal behaviors.” Go read the full article; it includes several videos of note, including one that animates the above notation while the 8-minute song is played, and one that explores the compelling similarities between humpback song and mockingbird songs. Also featured are many of the original notations done by McVay, which inspired this new take on it, and exceprts from a recent lecture by Katie Payne (see it here) that dives deep into the questions of cultural change and linguistics that are raised by the extraordinary nature of the these songs.

Southern right whales have begun giving birth in the waters around New Zealand.  Beginning in the 1920’s, none frequented waters around the New Zealand mainland, after an intensive decade of hunting in the 1800’s decimated populations.  In the 1990’s,  a few scattered sightings began, and in recent years, females and calves are started utilizing sheltered bays. According to Emma Carroll of Auckland University, the whales appear to have lost the knowledge that New Zealand was a valuable winter and calving habitat, but the early exploratory trips by individual whales seems to have led to it being “rediscovered.”

Ironically, considering the growing concern over the impacts of human noise on whales worldwide, early settlers in Wellington complained that whales in the harbor there kept them awake at night!  How the times have changed….

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.

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.

Jump on over to Scientific American to read this great overview of the many different ways that animals are using to adapt to increasing human noise in their habitats. The author is an NYU science reporting student, and she promises a new sound blog soon on Scienceline….

Can you hear me now? Animals all over the world are finding interesting ways to get around the human din

Paul Spong and Helena Symonds are legends in the field of whale research; since the early 1970’s they’ve dedicated themselves to studying orcas from their independent lab on an island between Vancouver Island and the mainland.  Over those many years, they’ve accumulated 20,000 hours of tapes, which are now being digitized and cleaned up (to remove hiss and other noise and make the orca calls more prominent) by George Tzanetakis of the University of Victoria.  A recent article in the Toronto Globe and Mail focuses on Tzanetakis’ work, which is being posted online for researchers and curious listeners as the Orchive.  The entire collection isn’t online yet, but there’s plenty!

Those of us  who know the pleasures of cueing up Newport Jazz or good ol’ Grateful Dead shows from online taper archives like Archive.org and Bill Graham’s Wolfgang’s Vault will be familiar with the scope of this project: right now I’m nearly half-way through a 45-minute “set” from 9/1/05 known on the Orchive as Tape 449A.  As with jam band and jazz taper archives, the quality is decent though not crystal clear, creating a great background stream of pleasurable audio, ebbing and flowing from quiet and calm to more active, interspersed with moments of truly exciting interplay and melodic joy.  The audio is presented with a basic spectrogram, and even field notes (the scientific version of Dick Latvala’s show notes):

A sweet set from 9/1/05

Visit the Orchive!

A key research paper from National Park Service and Colorado State scientists has been published in Trends in Ecology and Evolution.  The paper, which got a lot of press when it was first made available online in the fall, introduces two key new metrics for measuring the effects of noise on animals.  The first, “alerting distance,” is the distance at which sounds can be heard: these may be sounds made by a species to alert others to danger, or sounds made by predators (which prey animals want to hear, so as to take cover).  The second, is “listening area,” the full area around an animal in which it can hear other animals’ calls, footsteps, and wingbeats.  A key insight offered by this approach is that even moderate increases in background noise (from nearby roads, airplanes, or wind farms) can drastically reduce an animal’s listening area.  The paper, which was free while in pre-press, is now available only to subscribers to the journal or other academic journal services; an article published in Park Science magazine and free to view online introduces much of the same material (be sure to click on the links to the figures, as they illustrate the concepts very well): see the article here, and check out the entire special soundscapes issue of Park Science here.

A very good article in the Aspen Times introduces the research, and includes many extremely insightful quotes from the researchers.  Go read the whole article! Three bits that are especially worth keeping mind are:

• “The male sage grouse, in its mating displays, produces high-frequency popping sounds and swishing sounds,” Fristrup said. “It also uses a low-pitch hooting sound, which carries the farthest from the display area as a long-distance advertisement. The danger is, it doesn’t take a lot of noise to substantially reduce the range at which females or other males could hear that low-frequency hoot. So the attraction radius of the display ground could contract substantially with the inability to hear a hoot.” The authors note that some species can reduce the effects of masking by shifting their vocalizations. This is especially true when members of a species are communicating with each other. However, when the sounds a species depends on emanate from another species (such as a mouse burrowing under the snow, which an owl needs to hear as it hunts), there is less room for compensation.
• Carnivores like lynx, who sit at the top of the food chain, can be particularly sensitive to habitat degradation of any type — including auditory — since each individual requires a huge hunting territory. “If one part of the range of a top-level predator is compromised, it may not take much to squeeze it out,” Fristrup said.
• Contrary to what one might expect, noise is not always more disruptive when it’s louder. Snowmobiles or cars, for example, might be less disruptive to elk or deer than a hiker or cross county skier would be. “There’s pretty good evidence that so-called quiet use can disturb wildlife. If it’s a noisy source, the animal perceives it a long way off and can track its progress. There are no surprises, and it can go on feeding or doing whatever else. A quiet sound, like a snowshoer’s footstep, is only perceptible when it is very close, potentially startling the animal,” Fristrup said.

To read AEI’s detailed lay summary of the research paper, published here in December, see this link.

In the most promising development yet in using acoustics to deal with the spread of bark beetles in the American and Canadian west, researchers at Northern Arizona University have found that some beetles can be disrupted by playback of other beetle sounds. The tiny insects make squeaking noises as they tunnel through trees; the researchers have been manipulating the beetle sounds, which are above human hearing, and playing them back to the insects. The results drive them buggy: They attack each other, scamper in circles rather than straight lines and have tried to gnaw their way through Plexiglas covering a cross section of a tree in a lab in Flagstaff, Ariz.

A great article in The Missoulan included these tidbits from NAU researchers Richard Hofstetter and Reagan McGuire, Skye Stephens, an entomologist with the Colorado State Forest Service, and David Dunn, a sound artist who discovered and first recorded the beetle sounds:

“One of the questions is if we could effectively remove them from a particular tree or set of trees, where do they go, what happens to them?” Stephens said. “I’m very excited to see what happens next” with the research. Hofstetter and McGuire are eager to run tests on the ground to answer questions like that. Working with Dunn, they have applied for a patent on a device that pumps in noise to throw off the beetles’ destructive course. Hofstetter said the sounds are at a frequency that shouldn’t bother other species. The work has been a side project for the professor, who has struggled to scrape together funding for the research. McGuire is volunteering his time. “We’re hoping it’s going to lead to a whole new field,” Hofstetter said.

David Dunn, who has traveled the world collecting sounds of nature for his compositions, first started recording the inner life of trees in 2004. He took the kind of small microphone used in greeting cards to record and play, fastened it to a recycled meat thermometer and inserted it into the tree. While concerned about the dying trees and what they signal about climate change, Dunn has become intrigued by the beetles, “an absolutely fascinating form of life. I fell in love with them,” Dunn said. “But then we’re watching them cannibalize each other. I always think, ‘How bad is this karma?’

“But if something really positive about forest health comes of it, perhaps it’s worth the price.”

Dunn’s CD, The Sound of Light in Trees, was released by EarthEar; 100% of all sales revenues are donated by Dunn and EarthEar to support the Acoustic Ecology Institute.  See more on the CD and beetle project on AEI’s website.

I’ve just finished reading what must be the most exciting research paper I’ve seen this year, barely nudging out a similar paper addressing terrestrial noise impacts. A small group of researchers, with Chris Clark of Cornell as the lead author, took a giant step forward in addressing the impacts of ocean noise on the communication ranges of whales.  They came up with a clear and strikingly rigorous set of new metrics that will allow researchers and ocean planners to have a much more practical picture of how numerous noise sources combine to create cumulative impacts on acoustic habitat.  The new approach centers on the “Communication Space” of individual animals, as well as groups, and provides an intuitively obvious way to both imagine and assess the effects of ocean noise – measuring the area in which an animal can hear or be heard by others of its species.

My formal “lay summary” of this paper is reprinted in full below the fold, and I encourage anyone with a deep interest in ocean noise to read through that five-paragraph overview, or to download the paper yourself.  The key takeaway for those of you with a more casual interest in these issues is that in the test case that they used to illustrate their new approach, the researchers found that shipping noise has dramatically different impacts on different species, even though all three species they studied are low-frequency communicators.  In the area off Boston Harbor that they investigated, the critically endangered right whale is by far the most affected by shipping noise: on a day when two ships passed through the area (the average is often six), right whale Communication Space was reduced by an average of 84% over the course of the day, with several hours in which they could hear and be heard in an area less then 10% of that which would be expected without shipping nearby. Since right whales call back and forth to find each other as they form groups for feeding, this is truly worrying (though the key question of how a reduced communication range actually affects animals remains unanswered).  Fin whales and humpbacks were far less dramatically affected, with their Communication Spaces reduced by just 33% and 11% respectively.

These first examples focus on the effects of low-frequency shipping noise on low-frequency communication by large whales, but this approach can easily be used to address mid- or high-frequency noise sources (sonars, airguns) and higher frequency animal sounds such as those used for echolocation, opening a vast and exceedingly useful new doorway for biologists and ocean managers, as well as the general public, to appreciate the impacts of human sounds in the sea.   (click through for complete lay summary)

Read the rest of this entry »

An ongoing research project from the National Park Service Natural Sounds Program is about to publish a groundbreaking paper that outlines the many ways that even moderate increases in human background noise can create major impacts on animals.  The study proposes a new metric for use in bioacoustics research, the “effective listening area.”  This is the area over which animals can communicate with each other, or hear other animals’ calls or movements; as might be expected, animals focus especially on listening for sounds at the very edges of audibility, so that even a small increase in background noise (from a road, wind farm, or regular passing of airplanes) can drown out sounds that need to be heard.  The authors note analyses of transportation noise impacts often assert that a 3dB increase in noise – a barely perceptual change – has “negligible” effects, whereas in fact this increased noise reduces the listening area of animals by 30%. A 10dB increase in background noise (likely within a few hundred meters of a road or wind farm, or as a private plane passes nearby) reduces listening area by 90%.

In addition to introducing this important new metric, the paper provides a good overview of previous research that has addressed the impacts of moderate noise on various animals, including bats, antelope, squirrels, and birds.  The paper will be published next year, though an “in press” version is available for download.  A recent BBC article also covered this important new work.  A full detailed lay summary of this paper, as previously published on AEI’s science research page, appears below the fold: Read the rest of this entry »

Ongoing research by NOAA’s Northwest Fisheries Science Center continues to look more deeply into the effects of boat noise on Puget Sound orcas.  The research team, led by Marla Holt, had previously found that orca calls increase in volume in step with background boat noise: for each decibel of added background noise, their calls also got a decibel louder.  In their latest round of research, the team is trying to determine whether the background noise is diminishing their foraging success due to masking (drowning out) some of the critical group communication, and whether calling louder makes the animals use more energy.

Image courtesy National Geographic

A 20% population decline among the Southern Resident orcas during the late 1990’s has been attributed to a combination of fewer salmon, toxins, and vessel noise. According to a recent article on National Geographic.com, Holt, who will present the team’s preliminary findings in October at the Biennial Conference on the Biology of Marine Mammal in Quebec, said that their research indicates killer whale communication is particularly important during hunting. What’s more, previous studies in birds had suggested that the animals consume more oxygen to raise their voices above ambient noise, making their metabolic rates spike and burning up stored energy, Holt said, adding that it’s possible the same phenomenon could be occurring with killer whales, although it’s too early to know for sure.

NOAA’s recovery efforts for the orcas include new regulations that will keep whale-watching vessels 200 yards from orcas, as well as efforts to reduce toxin pollution and to restore salmon runs.  Longtime orca researcher Ken Balcomb feels it all comes down to the decline in salmon: “If you deny them the food, [there’s] basically no point in worrying about other factors,” Balcomb said. He calls the whale-watching limits “feel-good thing,” adding that “my observations over 35 years [are] that [whales] don’t really get disturbed by anything, much less vessels.”  Holt acknowledges the limits of the new regs, saying that “a lot of people would argue, Why focus on these vessel regulations? But it’s one thing we can do immediately.”  It appears to AEI that the question is not really whether the boat noise disturbs the orcas, but whether it may drown out parts of their foraging communication, making it more difficult for them to find and eat the few salmon that do remain available to them.  And, given their tenuous situation, if they are forced to use more energy to call during hunting, their overall health is likely to be at least somewhat affected.  Moreso, each time that a particular foraging attempt is aborted due to a noise intrusion, a larger bit of the daily energy budget has gone to waste.  Time will tell whether the new boat limits actually lower the received sound levels for foraging whales; if so, it’s a step in the right direction.

Fascinating discovery of the day: music written for monkeys, based on their vocalizations, finally triggers a notable response.  What follows is straight from the website of the composer, who also makes music for cats.  You can hear an NPR story on the monkey research here.

Many previous experiments on animal response to music composed for humans (hereinafter, “human music”) have been conducted, but none of these studies had demonstrated significant responses. Very recently a study of the effect of human music on cotton-topped tamarin monkeys was conducted at Harvard. The tamarins showed a slight preference for Mozart over German “techno” music, but preferred silence to either. This study was consistent with the findings of all previous studies: animals are largely indifferent to human music.

We performed tests at the University of Wisconsin on the same species of tamarins. As with all previous studies, the tamarins showed a lack of interest in the human music. By contrast, the effect on them of the species-specific music composed by David Teie was remarkably clear and convincing. They displayed a marked increase of activity in response to the music that was designed to excite them, while the “tamarin ballad” music induced a significant calming. This calming effect was measured against the baseline of silence; they moved and vocalized less and orientated more toward the audio speakers during and immediately following the playing of the tamarin ballad.

Following are quotes from a research paper about these experiments that will soon be submitted for publication. The psychologist Charles Snowdon, who conducted the testing and authored these statements, is a highly respected but extremely cautious and skeptical scientist not normally given to making sweeping statements: “Our predictions were supported. Music composed for tamarins had a much greater effect on the behavior of tamarins than music composed for humans. …tamarins displayed significant behavioral change only to the music that was specifically composed for them and were unaffected by human music.”

To the best of our knowledge, this marks the first time that an art form has been shown by scientific test and observation to engender the measurable appreciation of any species other than human. (Ed. note: true, little science has been done; yet there have been some compelling examples of animals themselves enjoying doing art: the painting gorillas and Thai Elephant Orchestra come quickly to mind.)

After a bit of a lull, I’ve spent much of the past couple days catching up on the folder full of research published in recent months, and summarizing key papers on the main Acoustic Ecology site.  Among the studies worthy of attention are:

• The first direct test of harbor porpoise sensitivity to seismic survey airguns confirms many observations from the field that this species is especially sensitive to noise; both temporary hearing loss and avoidance of sound occur at relatively low noise levels
• Orcas and dolphins seen to reduce foraging in the presence of boat noise
• Wind turbines don’t seem to replace most small wintering farm birds, but oil development noise can reduce forest bird abundance
• Right whales summer habitat is loud most of the time, suggesting a pressing need to identify their breeding grounds and assure they can hear each other there
• Two great overviews of fish hearing

See these and more at the AEI lay summaries of new research page.

The early 2009 issue of Conservation magazine, the popular press publication of the Society for Conservation Biology, has a great overview piece on the effects of noise on animals. It focuses on changes in animal behavior and song that have been observed over the course of the past decade, drawing on studies from several different researchers. Much will be familiar to AEI regulars, but it remains highly recommended for sharing with others and for the concise overview it provides.

See the article at http://www.conservationmagazine.org/articles/v8n2/not-so-silent-spring/

Been wondering what’s up with the great “Sonar Kills Whales”/”Everything’s Fine, Just Go Away” rhetorical battle between NRDC and the Navy? As you might suspect, the reality is not nearly so neatly defined as either of them might suggest….and if you’re up for digging into it more deeply, the Acoustic Ecology Institute has just posted an AEI FactCheck that explores three key questions:

• Dead Whales: How Common?
• Behavioral Reactions: Millions of Whales Affected, or Negligible Impact
• Additional Mitigation: Common Sense Precautions or Undermining Sailor Safety?

There’s a fair dose of decoding science and regulatory details in this document, as well as acknowledgment of the underlying unspoken ethical questions that lead to radically different perspectives on the same data.

Check it out at
http://www.AcousticEcology.org/srSonarFactCheck.html
AEI is a resource/information center for sound-related environmental issues, run by editor/writer Jim Cummings (yup, that’s me…). We’ve some how managed to become friends with top scientists and agency staff, major environmental groups, and even a few folks in the Navy and oil and gas industry. More at http://AEInews.org

As a new UK Navy report suggests that beaked whales made “potentially very significant” behavioral changes in response to mid-frequency active sonar signals, a team of scientists has just completed a pilot study that involved monitoring the detailed behavior of whales during a major Naval exercise. The UK military report details observations of whale activity during Operation Anglo-Saxon 06, a submarine war-games exercise in 2006. Produced for the UK’s Defence Science and Technology Laboratory, the study used an array of hydrophones to listen for whale sounds during the war games. Across the course of the exercise, the number of whale recordings dropped from over 200 to less than 50. “Beaked whale species appear to cease vocalizing and foraging for food in the area around active sonar transmissions,” said the report.  Read the rest of this entry »

Stellwagen Sanctuary Noise Monitoring to be Model for “Sound Budget” Research Worldwide – The hydrophone array deployed in Stellwagen Bank is far more than a ship-strike warning system; it is the first large field test of what many bioacousticians have been long calling for: a global network of monitoring systems that will dramatically increase our understanding of the distribution of human noise in the world’s oceans, and the ways local animals respond. NOAA researcher Sofie Van Parijs says the Sanctuary is a perfect place to build a case study that can provide a benchmark  Read the rest of this entry »

Urban Noise Threatens Dawn Chorus and Bird Populations – European researchers are increasingly concerned about accumulating evidence that urban and suburban noise is having dramatic effects on bird populations. Some birds may be adapting by developing new behaviors, perhaps changing dramatically enough to be considered new species: nightengales sing up to 14dB more loudly in the city (some at 95dB, enough to cause discomfort to human ears), great tits are singing at a higher pitch, and robins have abandoned their noisy dawn (i.e. rush hour) chorus and now sing at night, when it is quieter. Birds must hear each other in order to mate and warn each other of predators. Declining populations of house sparrows (down by two-thirds over the past couple of decades) and overall bird populations (down 20% in the past four years) could be due to difficulty in finding mates, or abandonment of urban and suburban habitat.Source: Daily Mail, 3/26/08 [READ ARTICLE]

Digital downloads of favorite Pulse of the Planet programs – Pulse of the Planet, the long-running 2-minute public radio feature, is now offering large collections of mp3 versions of shows, grouped in popular themes. The first three sets (23-49 shoes each, priced at $5-9) focus on hurricanes and tornadoes, whales, and global warming.  [WEBPAGE]