Crafty Crows Can Build Tools From Memory

iStock
iStock

Scientists have discovered yet another reason to never get on a crow's bad side. According to new research reported by Gizmodo, members of at least one crow species can build tools from memory, rather than just copying the behavior of other crows—adding to the long list of impressive skills that set these corvids apart.

For the new study, published in the journal Scientific Reports, an international team of scientists looked at New Caledonian crows, a species known for its tool usage. New Caledonian crows use sticks to pick grubs out of logs, sometimes stashing these twigs away for later. Tools are so important to their lifestyle that their beaks even evolved to hold them. But how exactly the crows know to use tools—that is, whether the behavior is just an imitation or knowledge passed down through generations—has remained unclear until now.

The researchers set up the experiment by teaching eight crows to drop pieces of paper into a box in exchange for food. The birds eventually learned that they would only be rewarded if they dispensed either large sheets of paper measuring 40-millimeters-by-60 millimeters or smaller sheets that were 15-millimeters-by-25 millimeters. After the crows had adapted and started using sheets of either size, all the paper was taken away from them and replaced with one sheet that was too big for the box.

The crows knew exactly what to do: They ripped up the sheet until it matched one of the two sizes they had used to earn their food before and inserted it into the dispenser. They were able to do this with out looking at the sheets they had used previously, which suggests they had access to a visual memory of the tools. This supports the "mental template matching" theory—a belief among some crow experts that New Caledonian crows can form a mental image of a tool just by watching another crow use it and later recreate the tool on their own, thus passing along the template to other birds including their own offspring.

This is the first time mental template matching has been observed in birds, but anyone familiar with crow intelligence shouldn't be surprised: They've also been known to read traffic lights, recognize faces, nurse grudges, and hold funerals for their dead.

[h/t Gizmodo]

Want to Give a Retired Police or Military Dog a Forever Home? Mission K9 Rescue Can Help

Mission K9 Rescue
Mission K9 Rescue

Over the course of their careers, working dogs perform lifesaving duties while assisting members of the police force and military. These dogs receive a lot of appreciation while they're on the job, but as they enter retirement, they're often forgotten in animal shelters. An organization called Mission K9 Rescue is dedicated to placing these dogs in loving forever homes after they've served the United States.

"Our mission is to give K9 veterans—and other working dogs who have served our country—safe, peaceful, and loving homes upon retirement from service," K9 co-founder and president Kristen Maurer tells Mental Floss. "There are so many animal-loving patriots in America, and most don't realize that many of these brave, selfless dogs often remain overseas much longer than needed when they are no longer able to work. Some do not receive adequate care. We bring awareness of their plight to the public, and we work tirelessly to rescue, reunite, re-home, rehabilitate, and repair these dogs so they can live out the rest of their days in a safe and comfortable environment."

Many retired dogs are abandoned in kennels—both in the U.S. and abroad—but for some, the situation is even more severe. According to Mission K9 Rescue, working dogs are sometimes euthanized en masse when they can no longer do their jobs. The organization aims not only to remove these dogs from harm's way, but to find them forever families that are a perfect fit for them.

After rescuing dogs from both the U.S. and overseas, Mission K9 Rescue matches them with new owners. If the dog has a past handler who is interested in adopting them permanently, reuniting the pair is a priority. For all other cases, the organization goes through a rigorous process to find dogs a brand-new home.

Mission K9 also specializes in rehabilitating dogs who have suffered either mental trauma or physical injuries in their work. Just like humans, canines can develop PTSD from working in stressful, high-pressure situations. After they're rescued, animals are given as much time as they need to decompress and reintegrate into society before they're adopted. On top of the mental demands, being a working dog causes physical strain, and Mission K9 provides medical care to dogs with injuries and other issues.

Anyone can apply to adopt a retired working dog from Mission K9 Rescue. If you're interested in bringing one into your home, you can fill out the application on the group's website.

German shepherd in a bed at home.
Mission K9 Rescue

Two dogs in the backseat of a car.
Mission K9 Rescue

Dog and owner in front of home.
Mission K9 Rescue

Some Fish Eggs Can Hatch After Being Pooped Out by Swans

iStock/olaser
iStock/olaser

A question that’s often baffled scientists is how certain species of fish can sometimes appear—and even proliferate—in isolated bodies of water not previously known to harbor them. A new study has demonstrated that the most unlikely explanation might actually be correct: It’s possible they fell from the sky.

Specifically, from the rear end of a swan.

A study in the journal Ecology by researchers at the Unisinos University in Brazil found that killifish eggs can, in rare cases, survive being swallowed by swans, enduring a journey through their digestive tracts before being excreted out. This kind of fecal public transportation system explains how killifish can pop up in ponds, flood waters, and other water bodies that would seem an unlikely place for species to suddenly appear.

After discovering that some plants could survive being ingested and then flourish in swan poop, researchers took notice of a killifish egg present in a frozen fecal sample. They set about mixing two species of killifish eggs into the food supply of coscoroba swans living in a zoo. After waiting a day, they collected the poop and dug in looking for the eggs.

Of the 650 eggs they estimated to have been ingested by the swans, about five were left intact. Of those, three continued to develop. Two died of a fungal infection, but one survived, enduring 30 hours in the gut and hatching 49 days after being excreted.

Because killifish eggs have a thick outer membrane, or chorion, they stand a chance of coming through the digestive tract of an animal intact. Not all of what a swan ingests will be absorbed; their stomachs are built to extract nutrients quickly and get rid of the whatever's left so the birds can eat again. In rare cases, that can mean an egg that can go on to prosper.

Not all fish eggs are so durable, and not all fish are quite like the killifish. Dubbed the "most extreme" fish on Earth by the BBC, killifish have adapted to popping up in strange environments where water may eventually dry up. They typically live for a year and deposit eggs that can survive in soil, delaying their development until conditions—say, not being inside a swan—are optimal. One species, the mangrove killifish, can even breathe through its skin. When water recedes, they can survive on land for over two months, waddling on their bellies or using their tails to "jump" and eat insects. A fish that can survive on dry land probably doesn't sweat having to live in poop.

The researchers plan to study carp eggs next to see if they, too, can go through a lot of crap to get to where they’re going.

[h/t The New York Times]

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