Wolves in Yellowstone, USA, new study


This video is called [2017] – National Geographic Documentary Wild – Wild Yellowstone She Wolf HD.

From S.J. & Jessie E. Quinney College of Natural Resources, Utah State University in the USA:

Wolf reintroduction: Yellowstone’s ‘landscape of fear’ not so scary after all

June 22, 2018

After wolves were reintroduced to Yellowstone National Park in the mid-1990s, some scientists thought the large predator reestablished a ‘landscape of fear’ that caused elk,

North American elk should not be confused with still larger moose (Alces alces) to which the name “elk” applies in British English and in reference to populations in Eurasia.

the wolf‘s main prey, to avoid risky places where wolves killed them. This fueled the emerging idea that predators affect prey populations and ecosystems not only by eating prey animals, but by scaring them too. But according to findings from Utah State University ecologists Michel Kohl and Dan MacNulty, Yellowstone’s ‘landscape of fear’ is not as scary as first thought.

“Contrary to popular belief, the wolf is not a round-the-clock threat to elk; it mostly hunts at dawn and dusk, and this allows elk to safely access risky places during nightly lulls in wolf activity”, says Kohl, who completed a doctoral degree at USU in 2018 and is lead author of the paper. “Despite their Hollywood portrayal as nighttime prowlers, wolves tend to hunker down at night because their vision is not optimized for nocturnal hunting.” With colleagues Daniel Stahler, Douglas Smith, and P.J. White of the U.S. National Park Service, Matthew Metz of University of Montana, James Forester of University of Minnesota, Matthew Kauffman of University of Wyoming, and Nathan Varley of University of Alberta, Kohl and MacNulty report their findings in an Early View online article of Ecological Monographs. The article will appear in a future print edition of the Ecological Society of America publication. The team’s research is supported, in part, by the National Science Foundation.

The researchers revisited data from 27 GPS radio-collared elk that had been collected in the early years after the reintroduction, 2001-2004, but never fully analyzed. These collars recorded the location of each elk every 4-6 hours. This was the first time GPS technology had been used to track Yellowstone elk, and no one imagined that elk might sync their habitat use to the wolf’s 24-hour schedule. Little was known about this schedule until researchers first equipped wolves with GPS collars in 2004.

“In the days before GPS, when we tracked wolves by sight and with VHF radio-telemetry, we knew they hunted mainly in the morning and evening, but we didn’t know much about what they did at night” says MacNulty, a veteran Yellowstone wolf researcher and associate professor in USU’s Department of Wildland Resources and the USU Ecology Center. “GPS data showed that wolves were about as inactive in the middle of the night as they were in the middle of the day.”

Kohl used the GPS data to quantify the 24-hour schedule of wolves, and he compared how elk use of risky places — sites where wolves killed elk — differed between periods of high and low wolf activity. “Elk avoided the riskiest places when wolves were most active, but they had no problem using these same places when wolves were least active,” says Kohl. “An elk’s perception of a place as dangerous or safe, its landscape of fear, was highly dynamic with ‘peaks’ and ‘valleys’ that alternated across the 24-hr cycle in response to the ups and downs of wolf activity.”

The ability of elk to regularly use risky places during wolf downtimes has implications for understanding the impact of wolves on elk and the ecosystem at large. “Our results can explain why many other studies found no clear-cut effect of wolf predation risk on elk stress levels, body condition, pregnancy, or herbivory”, says MacNulty. “If our results reflect typical elk behavior, then actual killing rather than fear probably drives most, if not all, of the effect of wolves on elk and any cascading effect on the plants that elk eat such as aspen and willow.”

This conclusion runs counter to popular views about the ecological importance of fear in Yellowstone and elsewhere. “Although our study is the first to show how a prey animal uses predator downtime to flatten its landscape of fear, I suspect other examples will emerge as more researchers examine the intersection between prey habitat use and predator activity rhythms”, says Kohl.

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Snowshoe hares’ camouflage, new study


This 2015 video is called Epic Hunting Chase of the Canadian Lynx and Snowshoe Hare in HD.

From The University of Montana in the USA:

How snowshoe hares evolved to stay seasonally camouflaged

June 21, 2018

Many animals have evolved fur or feather colors to blend in with the environment and hide from predators. But how do animals stay camouflaged when their environment changes with each new season? Researchers at the University of Montana recently discovered that hybridization played an important role in snowshoe hares’ ability to match their environment.

An international scientific team led by UM Associate Professor Jeffrey Good and graduate student Matthew Jones set out to discover how snowshoe hares have evolved to molt to a white coat in areas with prolonged winter snow cover while populations from mild coastal environments of the Pacific Northwest retain brown fur year-round.

“Like other seasonal traits, the autumn molt in snowshoe hares is triggered by changes in day length”m Good said. “But the color of their winter coat is determined by genetic variation that has been shaped by evolution to match the local presence or absence of snow.”

In a new article published in the journal Science, Good’s team discovered that the development of brown or white winter coats in snowshoe hares is controlled by genetic variation at a single pigmentation gene that is activated during the autumn molt.

“This result is exciting because it shows that critical adaptive shifts in seasonal camouflage can evolve through changes in the regulation of a single gene,” Jones said.

The genetic discovery came with a surprising twist.

“When we looked at the same gene in other closely related species”, Jones said, “we found that the brown version of the gene in snowshoe hares was recently acquired from interbreeding with black-tail jackrabbits, another North American species that remains brown in the winter.”

Hybridization between species has played a key role in the development of many domestic plants and animals, and recent research suggests that it is also surprisingly common in nature. In snowshoe hares, hybridization with black-tailed jackrabbits provided critical coat color variation needed to adapt to coastal areas where winter snow is ephemeral or absent. But what does this mean for snowshoe hares going forward?

“Brown winter coats are currently rare across the range of snowshoe hares”, Good said. “If snow cover continues to decrease due to climate change, brown winter coats may become more common in the future and play a critical role in the resilience of this species. These discoveries are helping us understand how organisms adapt to rapidly changing environments.”

UM Professor Scott Mills is a co-author on the paper. For this research, UM partnered with the Universidade do Porto and CIBIO-InBIO in Portugal, North Carolina State University, Arizona State University, Ecole Polytechnique Fédérale de Lausanne in Switzerland and University of Cambridge in the United Kingdom.

Stop British Conservative fox hunting plans


British anti-fox hunting demonstrators

By Peter Frost in Britain:

Friday, June 22, 2018

Unelectable and unspeakable but still chasing the inedible

We all know that Prime Minister Theresa May has always been in favour of fox-hunting because she has often told us so.

In return, no less than 84 per cent of the British public have told her and other hunting fans in Westminster that they do not agree with those outdated opinions.

Overwhelmingly the general public wants Labour’s 2004 ban of hunting with dogs to stay firmly in place.

Yet despite hunting being illegal for nearly 14 years, wild animals are still being hunted and killed in the British countryside and those responsible are getting away with it.

Hunts are still killing wildlife. They have found many ways to circumvent the law and get away with slaughtering many wild animals. They do it in many ways — through so-called trail hunting, abusing exemptions in the law and exploiting legal loopholes that mean thousands of animals are meeting cruel and bloody deaths in the countryside every year.

Landowners are still giving hunts and packs of hounds access to land in order to carry out activities barely disguised as a cover for illegal hunting.

Legislation is simply not strong enough to allow the ever-reducing number of rural police to come down hard on illegal hunting.

Fox-hunting has always involved posh country folk dressing up and setting their pack of dogs on a fox and then chasing it on horseback for miles across the landscape. What hunters call a sport most people see as vicious and outdated cruelty.

The public wants nothing to do with May’s idea of repealing the legal ban put in place by a Labour government in 2004.

One of the worst ways the hunts get around this 14-year-old legal ban is called “trail hunting.” Most registered fox and hare hunts claim now to be trail hunting — an activity that was not in existence or even thought off when the Hunting Act 2004 was drafted.

Trail hunting is an entirely new invention which uses an artificial animal scent trail — often fox urine.

It is is not the same as drag hunting, which is a legitimate long established country sport which existed before the Act and, although it also uses packs of foxhounds, is not intended to catch and kill animals.

Trail hunting, on the other hand, deliberately kills many foxes and hares despite the claim from the hunts that these deaths are all accidents. It was simply dreamed up as a false cover for illegal hunting.

Too often the police or the Crown Prosecution Service consider that a case involving trail hunting may be too difficult to prosecute as proving intent is very difficult with the current Hunting Act if the trail-hunting deceit is used. That is why the law needs to be strengthened.

It isn’t just foxes that are illegally hunted and killed. Police are investigating allegations of illegal deer hunting in south-west England, following claims that here too a traditional hunt has been chasing stags with packs of hounds.

The League against Cruel Sports has given evidence to police that the Quantock Staghounds have broken the law.

Although the Hunting Act 2004 banned the hunting of foxes and wild mammals using dogs, hunting deer without hounds remains legal.

Three traditional hunts continue to chase deer on horseback in Somerset and Devon. The law allows hunters to use up to just two dogs to locate wounded deer or to flush out prey.

Darryl Cunnington, a retired police officer and now a League volunteer has given Avon and Somerset police wildlife officers a file of evidence from an incident in January on the southern edge of the Quantock hills, near Bridgwater in Somerset.

His evidence revealed there were seven or eight hounds chasing deer across the moor and the hounds were not called off and may have been actively encouraged. There was no evidence of trail-laying, proving this was deliberate illegal hunting.

A separate incident in September 2016 — filmed by a League volunteer — shows six hounds chasing a deer in Willoughby Cleeve. The man who took the footage, Andy Kendall, was also a retired police officer.

In 2007, local huntsmen Richard Down and Adrian Pillivant were each fined £500 for hunting deer with dogs. The League estimates that around 200 deer are chased and killed every year. Its Animal Crimewatch hotline, received 66 reports of illegal deer hunting in 2017.

So why did May raise the question of hunting just before her misjudged and hastily called general election.

In the campaign she ditched plans that had promised the Tory faithful a free vote to allow the end of the ban on fox-hunting.

It was of course a crude attempt to repair the Conservatives’ reputation on animal rights. May had voted against the original ban when it was introduced by Labour. She told Andrew Marr that she had always supported fox-hunting but had never herself hunted.

Her rival for the job of prime minister, Andrea Leadsom, is an enthusiastic hunter. May made Leadsom environment secretary briefly after the election but soon replaced her with Michael Gove who didn’t take long to spot that a poll just before the election showed 67 per cent of voters believed fox-hunting should remain illegal.

Gove started a concerted Tory campaign to counter social media posts denouncing the party’s record on animal rights.

Labour canvassers discovered Jeremy Corbyn’s long-held views opposing fox-hunting were helping them enormously on the doorstep, while May’s U-turn seems to have unleashed a backlash among Tory supporters both inside and outside the Conservative party.

In previous elections, the Tories have been helped in rural areas by Vote-OK, a pro-hunting organisation mobilising its supporters to back the local Tory campaign. Now Vote-OK is livid at what it sees as May’s betrayal.

Countryside Alliance’s top man Tim Bonner has warned that ditching the hunting pledge would have serious consequences for May’s long-term future.

May’s long-term future? That will certainly take some hunting for.

Prevent wildlife-cars collisions


This 2017 video is called Wildlife crossings stop roadkill. Why aren’t there more?

From the University of Waterloo in Canada:

Many wildlife-vehicle collisions preventable

June 21, 2018

A new study from the University of Waterloo has found that Ontario could save millions by implementing simple measures to help prevent vehicle accidents involving wildlife.

The Waterloo study focused on Ontario. It concluded that many of the thousands of wildlife-vehicle collisions — some fatal — occurring each year could be prevented if authorities implemented a few, cost-effective strategies to minimize the occurrences.

Implementing strategies such as better signage, wildlife detection systems, fencing and wildlife crossings could help reduce financial and health-related impacts for people, emergency services and the insurance industry. The measures could also help prevent unnecessary loss in the wildlife populations.

“These collisions cost Canadians hundreds of millions a year in vehicle damage and medical costs, as well as traffic delays, emergency services use and increases in insurance premiums”, said Waterloo’s Associate Professor Michael Drescher, who co-authored the study with graduate student Kristin Elton. “Ontario is missing an opportunity here. The most efficient way to prevent these accidents is to integrate effective measures in wildlife conflict zones every time major road work is undertaken.”

The study looked specifically at Southern Ontario, which has the highest concentration of roads in Canada. With ever-expanding infrastructure having a significant impact on wildlife and their habitat, many of the cost-effective measures that could help reduce wildlife-vehicle collisions are underdeveloped in Ontario.

“Within Canada, the Rocky Mountain region is renowned as a leader in the management of wildlife-road conflicts, said Drescher, who estimates five to 10 per cent of car insurance premiums go to animal-related incidents. “They’ve realized the economics are simple. Adding measures to road construction projects only marginally impacts the overall budget, while saving millions in taxpayer money, insurance costs, and potentially lives.

“Governments have to balance many competing factors next with the technical elements of this problem, such as perceived financial constraints, public opinion and political motivations”, added Drescher. “When these factors are not managed right, wildlife management measures are delayed or never started.”

New extinct gibbon species discovery in Chinese tomb


This 2015 video is called Singing Gibbons.

By Bruce Bower, 2:00pm, June 21, 2018:

A 2,200-year-old Chinese tomb held a new gibbon species, now extinct

Researchers suspect that humans drove this previously unknown lineage to extinction

A royal crypt from China’s past has issued a conservation alert for apes currently eking out an existence in East Asia.

The partial remains of a gibbon were discovered in 2004 in an excavation of a 2,200- to 2,300-year-old tomb in central China’s Shaanxi Province. Now, detailed comparisons of the animal’s face and teeth with those of living gibbons show that the buried ape is from a previously unknown and now-extinct genus and species, conservation biologist Samuel Turvey and colleagues report in the June 22 Science. His team named the creature Junzi imperialis.

There’s currently no way to know precisely when J. imperialis died out. But hunting and the loss of forests due to expanding human populations likely played big roles in the demise of the ape, the researchers contend.

“Until the discovery of J. imperialis, it was thought that the worrying global decline of apes was a modern-day phenomenon”, says Turvey, of the Zoological Society of London’s Institute of Zoology. “We’re now realizing that there may have been numerous human-caused extinctions of apes and other primates in the past.”

The climate was relatively stable several thousand years ago, and no vertebrate extinctions have been definitively linked to natural climate shifts over the past 10,000 years. So “it is reasonable to conclude that Junzi became extinct as a result of human impacts”, says study coauthor Alejandra Ortiz, a paleoanthropologist at Arizona State University in Tempe.

Historical records indicate that gibbons with features similar to those of J. imperialis, as well as some other distinctive-looking gibbon populations no longer observed in the wild, inhabited central and southern China up to around 300 years ago, the researchers say. Most gibbons today are found in Southeast Asia.

The tomb is thought to have belonged to the grandmother of China’s first emperor, Qin Shihuang, who ordered the building of the Great Wall of China and the famous terra-cotta warriors (SN: 9/16/17, p. 19). Twelve pits with animal remains, including those of the gibbon, were found in the crypt. During Qin’s reign and throughout much of Chinese history, gibbons were thought to have noble traits, and royals often acquired gibbons as high-status pets. Ancient Chinese art includes many depictions of gibbons, too.

Turvey’s group compared a 3-D digital reconstruction of the gibbon’s skull, based on its skeletal remains, with 477 skulls from nearly all living species of gibbons and siamangs, a closely related ape. Digital images of the recovered gibbon’s upper and lower molar teeth were compared with 789 molars from 279 present-day gibbon and siamang individuals.

“The science in this paper is strong, but its message for the future of apes and all animals and plants on Earth today is dismal”, says biological anthropologist Brenda Benefit of New Mexico State University in Las Cruces. All species of gibbons living today remain imperiled, as do most other primates, due to serious challenges from habitat loss, hunting and the international trade in exotic pets (SN: 3/17/18, p. 10).

While the new report highlights long-standing human threats to gibbons’ survival, the ancient gibbon’s remains may not represent a new genus, holds biological anthropologist Terry Harrison of New York University. A partial skull from a captive ape of unknown geographic origin leaves crucial questions unanswered, including what the creature’s lower body looked like, Harrison says. Relatively complete skeletons of wild gibbons from Chinese sites dating to the past 10,000 years are needed to check the Shaanxi ape’s evolutionary ID, he contends.

How primates got fingernails, new research


This 2016 video says about itself:

Nails evolved from claws roughly 50 million years ago. Why did this happen and what purpose do nails serve?

Oldest evidence of nails in modern primates: “From hot pink to traditional French and Lady Gaga‘s sophisticated designs, manicured nails have become the grammar of fashion. Scientists have now recovered and analyzed the oldest fossil evidence of fingernails in modern primates, confirming the idea nails developed with small body size and disproving previous theories nails evolved with an increase in primate body size.” Read more here.

“Which came first, the nail or the claw? The answer is unclear, but researchers have discovered a clue: an early primate that had a toe bone with features of both a grooming claw and a nail. A fossil of the 47-million-year-old primate, Notharctus tenebrosus, had a lemur-like grooming claw on its second digit, but it was flattened, a bit like a nail, according to a new study in the journal PLoS One.” Read more here.

Evidence for a Grooming Claw in a North American Adapiform Primate: Implications for Anthropoid Origins: “Among fossil primates, the Eocene adapiforms have been suggested as the closest relatives of living anthropoids (monkeys, apes, and humans). Central to this argument is the form of the second pedal digit. Extant strepsirrhines and tarsiers possess a grooming claw on this digit, while most anthropoids have a nail. While controversial, the possible presence of a nail in certain European adapiforms has been considered evidence for anthropoid affinities.” Read more here.

From the University of Florida in the USA:

Fossils show ancient primates had grooming claws as well as nails

Why don’t we have them? Maybe because we have each other

June 20, 2018

Humans and other primates are outliers among mammals for having nails instead of claws. But how, when and why we transitioned from claws to nails has been an evolutionary head-scratcher.

Now, new fossil evidence shows that ancient primates — including one of the oldest known, Teilhardina brandti — had specialized grooming claws as well as nails. The findings overturn the prevailing assumption that the earliest primates had nails on all their digits and suggest the transition from claws to nails was more complex than previously thought.

“We had just assumed nails all evolved once from a common ancestor, and in fact, it’s much more complicated than that,” said Jonathan Bloch, study co-author and Florida Museum of Natural History curator of vertebrate paleontology at the University of Florida.

The findings are scheduled to be published today in the Journal of Human Evolution.

Grooming in mammals is not just about looking good. Thick body hair is a haven for ticks, lice and other parasites — possible health threats, as well as nuisances. Having a specialized claw for removing pests would be an evolutionary advantage, said Doug Boyer, an associate professor in the department of evolutionary anthropology at Duke University and the study’s lead author.

It’s one that has been retained in many primates. Lemurs, lorises, galagoes and tarsiers have nails on most of their digits and grooming claws on their second — and in tarsiers, second and third — toes.

So, why did the ancestors of monkeys, apes and humans lose their grooming claws? One possible answer: because we have each other.

“The loss of grooming claws is probably a reflection of more complex social networks and increased social grooming”, Boyer said. “You’re less reliant on yourself.”

This could explain why more solitary monkey species, such as titi and owl monkeys, have re-evolved a grooming claw, he said.

Researchers had thought grooming claws likely developed independently several times along the lines that gave rise to living primates. But these fossils suggest grooming claws were hallmark features of the earliest primates, dating back at least 56 million years.

They also come from five different genera of ancient primates that belonged to the omomyoids, the ancestors of monkeys, apes, humans and tarsiers — not the branch of primates that gave rise to lemurs, lorises and galagoes.

In 2013, Boyer was at the University of California Museum of Paleontology, sifting through sediment collected in Wyoming several decades earlier, when he found several curious primate fossils. They were distal phalanges, the bones at the tips of fingers and toes, from omomyoids. The shape of these bones reveals whether they support a claw or nail. Bones topped with a claw mimic its narrow, tapered structure while bones undergirding a nail are flat and wide. The distal phalanges that Boyer discovered looked like they belonged to animals with grooming claws.

“Prior to this study, no one knew whether omomyoids had grooming claws”, Boyer said. “Most recent papers came down on the side of nails.”

Meanwhile, Bloch, picking through collections recently recovered from Bighorn Basin, Wyoming, came across what looked like a “strange, narrow nail” bone. But when he compared it to modern primates, “it looked just like a tarsier grooming claw.” Smaller than a grain of rice, it matched the proportions of Teilhardina brandti, a mouse-sized, tree-dwelling primate.

Bloch and Boyer had co-authored a 2011 study describing the first fossil evidence of nails in Teilhardina. At the time, they believed the primate had nails on all its digits. Now, fossils were making them reevaluate their assumptions, not only about Teilhardina, but other omomyoids.

On the off-chance that they could add one more ancient primate to the growing list of claw-bearers, the pair drove out to Omomys Quarry, Wyoming, once inhabited by another genus of omomyoid, Omomys.

“We spent a day combing that site, never expecting to find something as tiny and delicate as a grooming claw,” Boyer said.

The team picked one right off the surface. They had found grooming claws at three independent sites from omomyoids spanning about 10 million years in the fossil record.

“That was the last nail in the coffin”, Boyer said.

Why did primates develop nails at all? The question is a contentious one, but Bloch and Boyer think the transition away from claws could have mirrored changes in primate movement. As we ramped up climbing, leaping and grasping, nails might have proven more practical than claws, which could snag or get in the way.

Grooming claws might seem insignificant, but they can provide crucial insights into ancient primates, many of which are known only from fossil teeth, Bloch said. These tiny claws offer clues about how our earliest ancestors moved through their environment, whether they were social or solitary and what their daily behavior was like.

“We see a bit of ourselves in the hands and feet of living primates”, Bloch said. “How they got this way is a profoundly important part of our evolutionary story.”

Beluga whales’ hearing, new research


This 2017 video is called Things You Should Know About Beluga Whales.

From Woods Hole Oceanographic Institution in the USA:

Beluga whales have sensitive hearing, little age-related loss

June 20, 2018

Scientists published the first hearing tests on a wild population of healthy marine mammals. The tests on beluga whales in Bristol Bay, Alaska, revealed that the whales have sensitive hearing abilities and the number of animals that experienced extensive hearing losses was far less than what scientists had anticipated.

The latter findings contrasted with expectations from previous studies of humans and bottlenose dolphins, which showed more hearing loss as they aged, says Aran Mooney, a biologist at Woods Hole Oceanographic Institution (WHOI) and lead author of two new studies on beluga whales. “But unlike the wild beluga population, the dolphins that were studied lived in a very noisy environment, as most humans do.”

At a time when noise in the ocean is increasing from human activities, such as oil and gas exploration and ship traffic, understanding the natural hearing abilities of whales and other endangered marine mammals is crucial to assessing potential noise impacts on animals and to management efforts to mitigate sound-induced hearing loss.

In the two related studies, WHOI researchers and their colleagues measured the hearing sensitivity of 26 wild belugas and then compared the audiograms to acoustic measurements made within their summer habitat in Bristol Bay to study how natural soundscapes-all sounds within their environment-may influence hearing sensitivity. The soundscape also reveals sound clues that the belugas may use to navigate. The first study was published May 8, 2018, in the Journal of Experimental Biology. Results from the soundscape study were published June 20, 2018, in the Journal of Ecoacoustics. “In the first paper, we characterized the beluga population’s hearing ability, which had not been done before in a healthy, wild population”, says Mooney. “And in the second paper, we put that into context to see how they might use acoustic differences in their habitat and how their hearing is influenced by the natural ambient noise in their environment.”

How do you test a beluga whale‘s hearing? Researchers applied the same screening method that doctors use to test the hearing of newborn babies who can’t yet vocally respond to whether or not they hear sounds: automated auditory brainstem response.

A suction cup sensor is gently placed on the whales’ head, just behind the blowhole, and another is placed on the back for reference. A series of quiet tones are played, and the sensors help measure the brain’s response to the sounds from the surface of the skin.

“It’s fairly straightforward,” Mooney says. “We just had to make a portable system that we could bring out into an extreme environment in order to perform the hearing tests.”

The test itself goes quickly, taking only about five minutes to measure each frequency. The most challenging part, says Mooney, is catching the participants.

For that, the researchers relied on the expertise of Alaskan Natives who hunt belugas. From small aluminum boats, the team would approach an individual adult whale-no calves were included in the study-in shallow waters of the bay. Taking care not to stress or injure the whale, they would catch it in a soft net. Marine mammal handlers, including teams from Georgia Aquarium, Shedd Aquarium, and Mystic Aquarium, would then get in the water to help secure the animal’s tail with a rope before moving it to a belly band (like a small stretcher) in the water next to a soft inflatable boat where the hearing tests took place.

“The belugas stayed relatively relaxed during the tests, seemingly employing a resting behavior that they may use to avoid killer whales“, Mooney explains. “When a killer whale is hunting them, belugas will often move to very shallow water and quietly stay there until they can safely return to deeper waters.”

In addition to the auditory testing, the researchers also performed a physical exam to assess the overall health, sex, and estimated age of each animal and obtained skin, breath, and blood samples to collect information on the whales’ hormone levels, microbiome bacteria, and other health-related data. The assessments were part of a beluga population health assessment program coordinated by the NOAA Fisheries Alaska Fisheries Science Center, the Alaska Department of Fish and Game, and Alaska SeaLife Center. Satellite transmitters were attached to some of the whales before release to study the whales’ movements.

The hearing tests revealed little hearing loss in the seemingly older members of the population, which could be because the estuary where the belugas reside is fairly quiet compared to more urban areas.

“Because there haven’t been any other studies of the hearing of wild marine mammals, we compared the results to previous studies of captive dolphins in San Diego and in Russia”, Mooney says. “The dolphins showed clear hearing loss as they aged, but the San Diego group lives in a very noisy environment, as most humans do.”

Mooney and colleagues also compared the wild belugas tests to those of belugas living in human care facilities. Both groups heard similarly well, and the authors suggest that it is likely due to the quiet environments in which they live.

“Sensitive hearing within a quiet soundscape could allow belugas to detect predators, navigate, and communicate with their young via low-amplitude signals,” Mooney explains. “This hearing sensitivity could be compromised in a noisier environment. It also suggests management concerns for animals that inhabit noisy areas, where they may already be showing greater proportions of hearing loss.”

The two studies are important to efforts to evaluate the effects of underwater noise on endangered Cook Inlet beluga whales, whose numbers have dwindled to an estimated 328. The species lives in habitats close to Anchorage, AK, and is exposed to noise from shipping, pile driving, construction, and explosive noise from nearby military bases.