Blue whale songs change, why?

This 2009 video from the USA says about itself:

Sounds of the Blue Whale – California

The haunting calls of blue whales can travel across thousands of miles of ocean, and Wild Chronicles is on a mission to find out why these solitary giants are so talkative. For the first time ever, National Geographic’s Crittercam® records both video and underwater sound of blue whales calling. The results reveal that these whales may not be so solitary after all — the calls could be about companionship.

From the American Geophysical Union in the USA:

Whale songs‘ changing pitch may be response to population, climate changes

November 28, 2018

Blue whales around the world are singing a little flat, and scientists may now have more clues as to the reason why.

A new study finds there’s a seasonal variation in the whales’ pitch correlated with breaking sea ice in the southern Indian Ocean. The new research also extends the mysterious long-term falling pitch to related baleen whales and rules out noise pollution as the cause of the global long-term trend, according to the study’s authors.

Blue and fin whales are among the loudest animals in the oceans as well as the largest. Only males sing, humming about as loud as large ships. The whales’ loud songs can travel more than 1,000 kilometers (600 miles) underwater, allowing the whales to communicate across vast oceans.

Blue whales have been dropping pitch incrementally over several decades, but the cause has remained a mystery. Now, the new study in AGU’s Journal of Geophysical Research: Oceans finds the same mysterious long-term trend of falling pitch in fin whales and Madagascan pygmy blue whales. Pitch, or the perception of how high or low a note sounds, is a result of the frequency of the sound wave, usually measured in hertz.

The authors of the new study use new data from the southern Indian Ocean to rule out noise pollution as the cause of the pitch change. Instead, the new study suggests the pitch drop is an anatomical consequence of singing less loudly. The whales’ calls could be quieter due to growing numbers of whales or changes in the ocean due to climate change, according to the study’s authors.

“We think it is something non-voluntary from the whale. Decrease the call intensity and it will decrease the call frequency, just because of the sound emission mechanism,” said Emmanuelle Leroy, lead author of the new study and a research fellow at the University of New South Wales in Australia.

The new research also uncovers a seasonal counterpoint in the calls of Antarctic blue whales, potentially related to the noise of melting sea ice. The new study finds blue whale calls in the southern Indian Ocean increase in pitch during the summer. The pitch could be increasing as whales sing louder to be heard over breaking sea ice, according to the study’s authors.

“Our hypothesis is that the call frequency change is again linked to call intensity and that the whale will adapt the call intensity to the variation of noise level,” Leroy said. “The noise is related to the increasing number of free icebergs in summer. When the ice sometimes cracks, like when you put ice in your drink, it makes noise. This noise is really strong and will propagate over really long distances, so we can hear this noise at our northernmost site, up to 26 degrees south.”

Analyzing whale songs

The new study analyzed more than 1 million songs from three species of large baleen whale: fin, Antarctic blue and three acoustically-distinct populations of pygmy blue whales. Six stationary underwater microphones recorded the calls over six years, from 2010 to 2015, in the southern Indian Ocean, an area spanning 9 million square kilometers (3.5 million square miles).

The stereotypical song of the Antarctic blue whale spans about 15 to 30 hertz, at the very bottom edge of human hearing, which ranges from about 20-20,000 hertz. Blue whale songs are in the range of the lowest, longest pipes of large cathedral organs. For consistency, the study measured the pitch of selected elements of each species’ song, which had fallen to about 25.6 hertz for the Antarctic blue and 96 hertz for the fin whale by the end of 2015.

In 2002, the pitch of the selected element of the blue whales’ call was closer to 27.5 hertz, a difference from the 2015 values equivalent to about a whole tone or major second interval in Western music tradition.

The new study found Antarctic blue whale calls are falling 0.14 hertz per year. Though fin whales, pygmy blue whales and Antarctic blue whale sing very different songs, the new study observed similar trends in call pitch, falling about 0.12 to 0.54 hertz per year, depending on the species.

The new research also found whale calls rise in pitch by 0.2 — 0.3 hertz from October through February.

Low pitches carry farther underwater, but the pitch change is likely too small to make a difference in the way the whale calls travel over long distances in the ocean and too subtle for the whales to detect any changes, according to the study’s authors

Changing soundscape

Unlike most of the world’s oceans, subject to an increasing mechanical cacophony, the southern Indian Ocean has grown quieter in recent years and its shipping traffic is limited.

Because the long-term trends in pitch drop are steady around the global range of the whales, the data from the Indian Ocean indicates the ongoing drop cannot be explained as a response to human-generated noise. Instead, the authors of the new study suggest the drop could be a byproduct of lower volume if the rebounding whale population doesn’t need to sing as loudly to reach other whales.

Recent population assessments estimate there are 10,000 to 25,000 blue whales globally, up from a few thousand at the end of commercial whaling in the 1970s, but still fewer than 10 percent of their numbers before the 20th century.

“Because the whaling stopped, the whale population is increasing. They can decrease their call intensity to keep in touch, because there are more whales. These calls are long distance communication,” Leroy said.

Alternatively, Leroy said, the whales may not need to be so loud because sound travels farther in ocean water made increasingly acidic by climate change. The speed and distance sound travels are affected by the temperature, pressure and chemistry of the ocean.

Naturally-occurring seasonal ocean noise could explain the seasonal variation in whale call pitch observed by the researchers in the southern Indian Ocean, however.

They observe the seasonal variation in pitch during the months of the austral summer when sea ice breaks up. Iceberg crackles are loud. They boom for thousands of kilometers in a frequency range overlapping the pitch of the Antarctic blue whales’ calls. To be heard over the noise the whales may need to get a little louder, the study suggests. Singing louder makes the pitch go up.

“What’s surprising is the long-term and short-term changes could have the same reason, a change in call intensity, but the change responds to two different causes,” Leroy said.


Humpback whales’ feeding trick, video

This 26 November 2018 video says about itself:

New humpback whale fishing tactic—pretending to be a pond

Watch humpback whales trick thousands of fish into becoming dinner

Learn more here.

Humpback whale jumps near Dutch coast

Humpback whale jumps near Kijkduin, photo by Jan van der Sluis

This is a 17 November 2018 photo of a humpback whale jumping out of the North Sea off Kijkduin neighbourhood in The Hague in the Netherlands.

The whale has been present in this area for some weeks.

Aquatic animals’ maximum jumping height is related to their body size, while ‘entrained water mass’ plays a limiting role: here.

Orca attacks on humpback whales, new study

This 2016 video says about itself:

Two Beautiful Humpback Whales Dance | Animal Attraction | BBC

Male humpback whales repeat each others’ songs and add to them so they become ever more complex and beautiful, showing off their memory and sheer volume.

From the Smithsonian Tropical Research Institute:

First study of Humpback whale survivors of orca attacks in the Southeastern Pacific

November 6, 2018

Summary: Scars left by orca attacks indicate that most victims are young whales on the first trip from breeding to feeding grounds. Increasing numbers of scars may mean that there are more orcas in the Southern Pacific, researchers say.

Humpback whales bear stark battle scars from violent encounters with orcas, also known as killer whales. Analysis of rake marks on more than 3000 humpback whale tails or flukes suggest that attacks on these undersea giants may be on the rise, according to a new study in Endangered Species Research.

“We set out to discover where, when and at what age humpback whales in the Southeastern Pacific are attacked by orcas“, said Hector M. Guzman, marine ecologist at the Smithsonian Tropical Research Institute.

Orcas, Orcinus orca, like humans, are apex predators. Although they can feed on more than 20 different species of cetaceans, they usually prefer sea lions, fur seals, fish and sea birds. “Because the chances of observing rake marks on young, vulnerable whales increased in the last 20 years, we think that killer whale attacks on humpback whales may be more common now than they were in the past, perhaps due to the recovery of whale breeding stocks in the Southeast Pacific after hunting was prohibited”, said Juan Capella, lead author and marine biologist from Whalesound Ltd. in Chile.

This extraordinary international team studied photos of whales at shallow, warm-water breeding grounds in Panama’s Las Perlas Archipelago, Gorgona Island and Malaga Bay in Colombia and Salinas and Machalilla in Ecuador and at cold water feeding grounds in Chile’s Magellan Strait and the Gerlache Strait off the western Antarctic Peninsula. They found that 11.5 percent of adult whales and 19.5 percent of calves carried battle scars, numbers similar to those reported from the North Pacific, the North Atlantic, eastern Australia, Tonga and New Caledonia. “The number of scars borne by an individual whale didn’t seem to change from year to year, suggesting that orcas primarily attack calves during their first migration”, said Fernando Felix, marine biologist from the Pontifica Universidad Catolica and the Whale Museum (Museo de Ballenas) in Ecuador. They carry their scars for the rest of their lives.”

Because young whales at feeding grounds had more scars than young whales at breeding grounds, researchers suspect that orcas prefer to attack young whales. Scarred female whales who were attacked by orcas as calves arrived at Magellan feeding areas with a higher number of calves than non-scarred females, suggesting that maybe they were better at evading orcas and defending their young from attack because they had survived an attack in the past.

“We want to underscore the importance of transnational studies to better our understanding of marine environments and their inhabitants as we recommend policies that work both for the health of the ocean and for the beneficiaries of its wealth”, Guzmán said.

Computer algorithms are playing a growing role in analyzing hydrophone audio data when monitoring marine life, but human listeners can complement and enhance these algorithms. A project known as Orcasound has produced a web application that will enable citizen scientists to listen to livestreaming audio from hydrophones near the San Juan Islands: here.

Watching whales with satellites

This 2016 video from the USA says about itself:

The WhaleWatch project supported by NASA’s Applied Sciences Program uses NASA satellite environmental data to predict the occurrence of whales off the west coast of the United States. WhaleWatch makes that information available on a NOAA-hosted website to help protect whales from human activity.

From the British Antarctic Survey:

Watching whales from space

November 1, 2018

Scientists have used detailed high-resolution satellite images provided by Maxar Technologies’ DigitalGlobe, to detect, count and describe four different species of whales. Reported this week in the journal Marine Mammal Science, this study is a big step towards developing a cost-effective method to study whales in remote and inaccessible places, that will help scientists to monitor population changes and understand their behaviour.

Each species was observed in one of their known aggregation areas, where individuals come together to congregate: southern right whales off Argentina, humpback whales off Hawaii, fin whales in the Pelagos Sanctuary in the Mediterranean and grey whales off the coast of Mexico. Already it has helped whale conservation bodies to identify 10 key inaccessible whale populations that would benefit most from the application of satellite imagery in studies.

Lead author Hannah Cubaynes, a whale ecologist at British Antarctic Survey (BAS) and University of Cambridge explains:

“This is the most detailed imagery of whales captured by satellites to date. It’s exciting that the improved resolution (now at 30 cm) reveals characteristic features, such as flippers and flukes, which can be seen in the images for the first time.

“Whales live in all oceans. Many areas are difficult to access by boats or planes, the traditional means of monitoring whales. The ability to track whales without travelling to these remote and inaccessible areas, in a cost-effective way, will be of great benefit to conservation efforts for whales.”

The study also shows some species are easier to identify by satellite. Fin and grey whales are the easiest to identify due to their body colouration, which contrasts with surrounding water. Humpback whales and southern right whales are more difficult to detect as they are a similar colour to their environment. In particular, the acrobatic behaviour of humpback whales makes them harder to see as they splash about so much and so their body shape is often obscured.

The team studied seven huge images of the open ocean taken by DigitalGlobe’s WorldView-3 satellite, covering over 5000 km2 — an area the size of the UK county of Norfolk or the U.S. state of Delaware.

Whale ecologist Dr Jennifer Jackson at BAS, an author on the paper, is due to embark on an expedition to the sub-Antarctic island of South Georgia in December to study southern right whales. She says:

“This new technology could be a game-changer in helping us to find whales remotely. Critically endangered whale populations like the Chile-Peru right whale (thought to winter in Patagonia) could really benefit from this approach.

“My project, looking at southern right whales around South Georgia, will examine if the species has made a recovery following the end of whaling. In recent years, many deaths have been seen on their nursery grounds at Peninsula Valdes. Satellite-based technology could prove very useful for measuring trends in whale populations such as these southern right whales, in future.”

This work was funded by the MAVA Foundation and the UK Natural Environment Research Council. DigitalGlobe provided imagery for this study.

London Natural History Museum highlights, video

This video from London, England says about itself:

Highlights from our year 2017/18 | Natural History Museum

29 October 2018

The past year has been a busy one. More than 4.5 million people visited our South Kensington site, and Hintze Hall was transformed with a diving blue whale skeleton suspended from the ceiling.