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When Poachers Kill Their Mothers, Elephant Daughters Hold Social Networks Together

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In elephant families, it’s the matriarchs who call the shots. They decide where a group goes, where it eats and when. They’re also the glue that holds elephant societies together. Elephants have a tiered social network of small “core groups” of close relatives, and larger, less cohesive “bond groups” and “clan groups” that include distant relatives and acquaintances. Older matriarchs with lots of social ties are the hubs that connect all these groups to each other. 

These older female leaders are also frequent targets for ivory poachers because of their large tusks. When they’re killed, other elephants not only lose their mothers, sisters, and grandmothers, but also their links to the rest of their social networks. 

In other animal societies, studies have shown that removing individuals who act as social hubs can collapse such networks. With demand for ivory leading to tens of thousands of elephant deaths a year, researchers feared that the same thing would happen to elephants. A new study published in the journal Current Biology shows, though, that elephant societies are more resilient than expected because younger females step into their mothers’ connective roles in the social network. 

Biologists Shifra Goldenberg, Iain Douglas Hamilton, and George Wittemyer explored how elephant networks respond to the “selective knockouts” caused by poaching by looking at data they had collected while studying more than 100 elephants over the last 18 years in Kenya’s Samburu National Reserve. They knew many of the elephants by the shape of their ears, their scars and other body markings, and even their behavioral quirks. They also knew which elephants hung out together and how their different groups were connected. 

The researchers went back to their observations and reconstructed the Samburu elephants’ social network at different points between 1998 and 2014, during which there were stretches of relatively little poaching and a recent period of intense poaching. 

They found that over those 16 years, the average age of the Samburu elephants became much younger as older elephants were killed. There was a high turnover in the population’s adult females, and less than one-third of the elephants that the researchers encountered in 1998 were still alive last year.

Despite the death toll, the Samburu social network didn’t fall apart. It remained intact because daughter elephants stepped in to fill the roles that were left behind by their mothers. In some of these cases, the new matriarchs were barely fully grown, but their surviving relatives still rallied around them as the oldest females in the family.

These younger elephants not only took over the leadership of their core groups, but filled in the connective roles in the bigger network, often replicating the positions held by their mothers. Daughters maintained the social ties and relationships their mothers had built when they were alive, keeping their core group connected to the others in the bond group through matriarchs that their mothers had known, or their daughters if both moms had died. This helped them to keep the network intact with more or less the same structure that had existed before. When daughters couldn’t recreate their mothers’ networks exactly, they used the social opportunities that their mothers had provided them to strengthen relationships with elephants that were once only distant contacts of their moms, thus creating new bond groups.

The resilience of the elephants’ social structure is good news, but the researchers warn that there’s more work to be done before we know all the consequences of these families losing their oldest members. Even with the leadership roles filled and social ties maintained, elephants groups may run into problems with younger matriarchs in the lead. They lack the experience and knowledge that their mothers accrued over time, and other research has shown that older matriarchs are better than younger ones at distinguishing and responding to predators and other threats, and that families with older leaders have higher reproductive rates. The researchers plan to keep monitoring the Samburu elephants to see how these rebuilt families fare over time. 

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Animals
Watch a School of Humpback Whales 'Fish' Using Nets Made of Bubbles 

Just like humans, humpback whales catch many fish at once by using nets—but instead of being woven from fibers, their nets are made of bubbles.

Unique to humpbacks, the behavior known as bubble-net feeding was recently captured in a dramatic drone video that was created by GoPro and spotted by Smithsonian. The footage features a school of whales swimming off Maskelyne Island in British Columbia, Canada, in pursuit of food. The whales dive down, and a large circle of bubbles forms on the water's surface. Then, the marine mammals burst into the air, like circus animals jumping through a ring, and appear to swallow their meal.

The video offers a phenomenal aerial view of the feeding whales, but it only captures part of the underwater ritual. It begins with the group's leader, who locates schools of fish and krill and homes in on them. Then, it spirals to the water's surface while expelling air from its blowhole. This action creates the bubble ring, which works like a net to contain the prey.

Another whale emits a loud "trumpeting feeding call," which may stun and frighten the fish into forming tighter schools. Then, the rest of the whales herd the fish upwards and burst forth from the water, their mouths open wide to receive the fruits of their labor.

Watch the intricate—and beautiful—feeding process below:

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Big Questions
Why Do Dogs Love to Dig?
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Dog owners with green thumbs beware: It's likely just a matter of time before Fido turns your azalea bed into a graveyard of forgotten chew toys. When dogs aren't digging up your prized garden, they can be found digging elsewhere in your yard, at the beach, and even between your couch cushions at home. But what exactly is behind your dog's drive to turn every soft surface he or she sees into an excavation site?

According to Dr. Emma Grigg, an animal behaviorist and co-author of The Science Behind a Happy Dog, this behavior is completely normal. "When people say 'why do dogs dig,' the first thing that always comes to mind is 'well, because they're dogs,'" she tells Mental Floss. The instinct first appeared in dogs' wolf ancestors, then it was amplified in certain breeds through artificial selection. That's why dogs that were bred to hunt rodents, like beagles and terriers, are especially compelled to dig in places where such animals might make their homes.

But this tendency isn't limited to just a few specific breeds. No matter their original roles, dogs of all breeds have been known to kick up some dirt on occasion. Beyond predatory urges, Dr. Grigg says there are two main reasons a dog may want to dig. The first is to cool off on a hot day. When stuck on an open lawn with little to no shade, unearthing a fresh layer of dirt untouched by the sun is a quick way to beat the heat.

The second reason is to stash away goodies. Imagine your dog gets bored with chewing his favorite bone but knows he wants to come back for it later. Instead of leaving it out in the open where anyone can snatch it up, he decides to bury it in a secret place where only he'll be able to find it. Whether or not he'll actually go back for it is a different story. "There's a disconnect with modern dogs: They know the burying part but they don't always know to dig it up," Dr. Grigg says.

Because digging is part of a dog's DNA, punishing your pet for doing so isn't super effective. But that doesn't mean you should stand idly by as your yard gets turned inside-out. When faced with this behavior in your own dog, one option is to redirect it. This can mean allowing him to dig in a designated corner of the yard while keeping other parts off-limits, or setting up a raised flowerbed or sandbox especially to satisfy that urge. "You can get him interested in the area by burying a couple bones or some interesting things in there for him to dig," Dr. Grigg says. "I like the idea of buried treasure."

If your dog's motive for digging is more destructive than practical, he may have an energy problem. Dogs require a certain amount of stimulation each day, and when their humans don't provide it for them they find their own ways to occupy themselves. Sometimes it's by chewing up shoes, toppling trash cans, or digging ditches the perfect size for twisting ankles. Fortunately, this is nothing more walks and playtime can't improve.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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