Digitized logbooks from the 1800s reveal a steep decline in strike rate for whalers.
Until someone works out a way to communicate with them, we can't really know how smart whales are. We do know they have the largest brains of any animals on the planet—of course, big is a thing they do really well altogether—and that their brains have more cortical convolutions than any other creature, including humans. There are indications that they're quite intelligent.
If that's so, however, why did 19th-century whalers in the North Pacific find it so easy to drive them to the edge of extinction? Didn't they see what was happening? New research published by the Royal Society in the U.K. apparently has an answer to that question, and it is "yes." An analysis of newly digitized whalers' log books finds that whalers' ability to harpoon sperm whales dropped precipitously after initial successes.
One possible explanation for the falloff would be that whalers' competence somehow degraded over time, but that doesn't seem especially logical. A more likely interpretation is that whales warned each other and modified their behavior to avoid the ships. If this is so, it suggests several thrilling things about the animals. First, they apparently shared information about the new predators, and second, they developed an effective evasive strategy.
A good look at mariners’ records
Credit: Aris Suwanmalee/Adobe Stock
The paper was written by cetacean experts Hal Whitehead of Dalhousie University in Halifax, Nova Scotia and Luke Rendell of University of St. Andrews in Scotland, along with data scientist Tim. D. Smith. Whitehead and Rendell are co-authors of "The Cultural Lives of Whales and Dolphins."
The researchers were working from the logbooks of American whalers operating between 10° and 50° in the North Pacific Ocean in the 19th century. The daily logs listed a ship's noon position, the number of sperm whales sighted, and how many whales were harpooned ("struck") or processed ("tried"). These records allowed the researchers to identify the date on which first contact with local whales occurred. From there, they were able to calculate the rate at which whales were encountered over the subsequent years.
The researchers found that about 2.4 years after first contact, whalers' strike rate fell by 58 percent.
At first, it seems the whales didn't quite know what to do about the whalers and responded to them similarly to the manner in which they defend themselves against the only predator they'd known up to that point: orcas. They formed defensive circles, their powerful tails pointed out to fend off their attackers. Unfortunately, this provided no defense against harpoons and likely made whaler's jobs easier by gathering groups of whales together where they could be easily killed.
Soon however, the leviathan strategy shifted and whales took to swimming upwind away from whalers' ships, an effective evasive maneuver that kept them ahead of the wind-driven boats. As White tells The Guardian, "This was cultural evolution, much too fast for genetic evolution."
Whale social learning and strategy
Spectrogram of a humpback whale song
Credit: Spyrogumas/Wikimedia Commons
While there remains debate over whether whale communities exhibit characteristics we'd recognize as culture, examples of what seems to be social learning support the idea that it does exist.
Whales are known to communicate with each other over large distances through their haunting—and mysterious to us—songs. These songs provide some hard-to-argue-with evidence for social leaning among whales: They evolve over time, and as they change, those changes are reflected by entire local whale populations. "We don't have to do anything but observe it to know that there's no explanation other than learning from others that can account for this," wrote Whitehead and Rendell to NPR in 2015.
Rendell wrote in Science in 2013 about what seems to be an innovation that was shared among whales: the spread of a particular type of feeding, "lobtailing," that seems to have spread from one humpback whale in 1980 to hundreds in a wider area over the next few decades.
There are also examples of cetaceans clearly using strategy, such as the manner in which orcas hunt together for Weddell seals, described by NOAA scientist Bob Pitman. The seals attempt to evade the orcas by remaining out of the water on ice floes. The orcas synchronize their flukes to create waves that either knock a seal off of a floe, or break the ice apart. Once the seal is in the water, the orcas blow bubbles under the water and apparently using their tails to create enough turbulence that the seal finds it harder to get back on the ice. If it does get out to safety, the orcas do it all over again until, according to Pitman, by about the fourth attempt, they usually have their prey, which they share.
And then there's the whales' evasive tactics for dealing with 19th-century whaling ships.
Back to the present and future
Unfortunately, modern vessels , equipment, and strategies were not as easy to evade, and whale populations were severely depleted in the 20 century. And while that threat is hopefully diminishing, modern fishing tactics such a long-line fishing that hooks whales, the intrusion of human noise in the oceans, plastics and other floating waste, and climate change means that today's seas are just as challenging as ever to whales. Maybe moreso. And nobody can outswim climate change.
Humpbacks swap songs at remote group of islands in the South Pacific.
- A whale's song reflects its geographical and social history.
- A new study identifies for the first time a major migratory crossroads where whales meet.
- The discovery sheds light on the mystery of how whale songs evolve across the Pacific.
To the northeast of New Zealand in the South Pacific lie six islands referred to as the Kermadec Islands. The group has a dark history with whales since sperm whales, humpbacks, and southern right whales where nearly hunted to extinction there in the past. That's changed, though, and what would be the largest marine preserve in the world is under consideration for these islands: the 620-square-kilometer Kermadec Sanctuary.
Humpback whale songs have long been an area of fascination and study. What are they for, and what do they mean? We know that there are songs associated with different breeding grounds, but these songs tend to grow in length and complexity over the course of a whale's lifetime, becoming more and more difficult to parse.
Researchers suspect that at least some of the embellishments come from other whales encountered along the way, providing clues about a whale's social history and where it comes from. However, the mechanism that would allow sharing across such widely spaced migratory routes to summertime feeding grounds in Antartica has been a puzzle.
The authors of a report published this month in Royal Society Open Science have just confirmed the scientists' hunch by filling in this blank. It turns out the Kermadecs — and in particular Rangitahua/Raoul Island — are a major crossroads at which the many migratory paths traveled by Oceania whales converge. This is where whales meet and exchange tunes, a few of which the researchers have now unraveled.
Where the twain meet
It's been known that whale songs tend to cross in waves eastward across the South Pacific, from Australia to French Polynesia, over the course of about three years. "While convergence and transmission have been shown within a whale population during migration and on their wintering grounds, song exchange and convergence on a shared migratory route remained elusive," recalls Dr. Ellen Garland of the University of St. Andrews.
There's evidence of song sharing within groups, but not so much across them. The convergence of different routes near the Kermadecs changes that. Says St. Andrews' Dr. Luke Rendell, "Song themes from multiple wintering grounds matched songs recorded at the Kermadecs, including a hybrid of two songs, suggesting that multiple humpback whale populations from across the South Pacific are traveling past these islands and song learning may be occurring."
Image Source: NASA
Songs of the sea
During September and October 2015 the researchers from the School of Biology at the University of St. Andrews in the U.K. recorded the songs of whales passing by the Kermadecs. The also captured songs at whale feeding and breeding locations east and west of Australia, and across the western and central parts of the South Pacific.
Their careful transcriptions of recordings from 52 whales overall resulted in the identification of three basic types of songs. As in human music, songs are comprised of groups of themes, which are groups of phrases, which themselves are groups of notes.
- Most common in the central Pacific — near the Cook Islands and French Polynesia — was Song Type. 1.
- Song Type 2 was heard most frequently in the western ocean, near Tonga, West Caledonia, and Niue.
- Coming exclusively from just east of Australia was Song Type 3.
Most of the songs recorded were Type 2 songs, from the western Pacific. Almost none came from east Australia, and only a few from the central ocean. Two of these, labeled in the study as Songs 1a and 1b, were quite similar.
By comparing similarities and difference in themes and phrases researchers were able to tell where each whale had been born, confirming these identifications with photographs and genetic markers.
There are likely other migratory junctions at which new phrases and themes may be exchanged, but the Kermadecs are the first such place that's been found.
A Swiss scientist identifies the top predator in the world in a new study.
Who are the world's top predators? It's not humans, killer whales or tigers. The creatures that kill and consume the most amount of prey per year are lowly spiders. Such is the conclusion of illuminating research by a Swiss spider scientist.
There are an estimated 25 million tons of spiders in the world, which hunt and eat between 400 to 800 million tons of prey every year. Most of the prey would be insects, with some occasional frogs, lizards, fish and even bats. By comparison, in that same year humans would consume about 400 million tons of meat and fish, according to the Food and Agriculture Organization of the United Nations (FAO). Whales would chow down on about 280-500 million tons of seafood in the same time span.
If the 3200 or so tigers in the world eat up to 25 pounds of prey per day, it can be estimated that they eat about 13 thousand tons of prey annually. Tigers are also no match for spiders.
The lead author of the study, Dr. Martin Nyffeler from the University of Basel, has been studying spiders for 40 years and was inspired to make this calculation by “The World of Spiders," a 1958 arachnology book which proposed that if you combine the weight of all insects killed each year by British spiders, the amount would be greater than the total weight of all the humans in Britain.
A European garden spider (Araneus diadematus) wraps its prey, a mosquito, in silk on September 13, 2016 in Lille, France. (Photo credit: DENIS CHARLET/AFP/Getty Images)
Spiders, in case you are wondering, are not insects. They are arachnids, creatures that have two body parts, eight legs, simple eyes, and no wings or antennae. Insects, on the other hand, have three body parts, six legs, compound eyes and most often two pairs of wings.
The new study really highlights how much 45,000 species of spiders in existence contribute ecologically.
“Our calculations let us quantify for the first time on a global scale that spiders are major natural enemies of insects. In concert with other insectivorous animals such as ants and birds, they help to reduce the population densities of insects significantly," says Dr. Nyffeler. “Spiders thus make an essential contribution to maintaining the ecological balance of nature."
And in case none of this convinces you and you still think spiders are kind of creepy, consider that on average they have a population density of 131 individual spiders per square meter on earth, but in "favorable" conditions it can be up to 1,000 individuals per square meter. They are mostly everywhere.