CLOSE

Cuckolded Sparrow Fathers Stop Feeding Their Kids

“Predictably Philandering Females Prompt Poor Paternal Provisioning”—that’s the name of a recent report on infidelity in house sparrows. The paper was published in The American Naturalist.

Monogamy means different things to different people—and different animals. House sparrows mate for life, yet years of observation of birds in the wild suggest that they’re also pretty prone to sleeping around. An international team of researchers had a lot of questions about how this works. Are house sparrows really that promiscuous, and, if so, does such behavior pay off? How do the mates of cheating sparrows respond? And how does that affect their kids?

To find out, the researchers set up shop on Lundy Island, an itsy-bitsy spot in the UK’s Bristol Channel. They caught, tagged, and took tiny tissue samples from 200 male birds and 194 females, then released the birds and watched the avian soap opera unfold. Tiny implanted trackers made it possible to tell which bird was which, and when that bird had entered his or her nest.

"Lundy is a unique natural laboratory because it is almost a closed system,” said lead author and Imperial College of London biologist Julia Schroeder in a press statement. “Very few birds leave the island or arrive from the mainland. In the entire 12 years, only four birds immigrated to Lundy, possibly carried by boat."

During that same period, the birds formed 313 pairs and produced 863 broods of baby birds. DNA tests of the birds’ tissue samples, and those of their babies, allowed the researchers to see quite plainly which sparrows were dallying outside their partnerships. A lot of them, it turns out: 38 percent of the broods included offspring from outside partners. Nearly all the couples stayed together once they had bonded, but both male and female birds cheated on their partners.

When those results were matched to video of the sparrows’ behavior, a trend emerged: Cuckolded male sparrows stopped tending to their chicks. This is a big deal for sparrows, a species that depends on care from both parents.

How could the male sparrows tell when their partners had strayed? It wasn’t from looking at the chicks and thinking, “Hey, wait a minute.” The researchers tested this by swapping out a couple’s chicks when they weren’t looking. Dad sparrows couldn’t tell which chicks were theirs, and treated all the little ones interchangeably.

"If chicks were switched into a nest where the female was faithful, then the father at that nest kept up his hard work providing for the chicks, suggesting they have no mechanism, such as smell, to determine which chicks are theirs," Schroeder said.

Instead, the birds are likely relying on context clues. As in: If your mate is going out a lot, and not with you, something might be up. “The males may use cues from the female’s behavior during her fertile period,” Schroeder said, “for example, how long she spends away from the nest.”

Here’s the thing: Animals don’t just sleep around for no reason. Some earlier studies had theorized that cheating might help female sparrows bring fresh genetic material into their nests while maintaining the social stability of a partnership. But if a cuckolded dad starts starving his kids, what’s the benefit?

There may not be one, the researchers say. It’s possible that the sparrows’ cheating hearts are just an evolutionary holdover from the days before the species became monogamous. Or, rather, “monogamous.”

arrow
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:

Original image
iStock
arrow
Big Questions
Why Do Dogs Love to Dig?
Original image
iStock

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.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios