Ravens Can Hold Grudges for Weeks, Study Finds

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Never cross a corvid. Crows have been known to hold grudges, and research says that ravens do, too. A new study in Animal Behavior spotted by The Verge finds that ravens remember the nature of their interactions with humans and can remember how the experience went for up to a month afterward.

The study, which was conducted by researchers at the University of Vienna and Lund University in Sweden, presented ravens with two types of interactions with human experimenters: some that could be considered fair and others unfair.

The nine ravens had all been hand-raised in captivity by humans. (The paper delightfully includes their names, which are: Laggie, Tom, Nobel, George, Horst, Louise, Joey, Rocky, and Paul.) The birds were trained to exchange a low-quality food (bread) for something they liked more (cheese). The ravens had to take a risk in giving the human their snack, though. They could give away the bread and receive cheese in return, but there was always the chance that they would give away their bread and not get anything back.

In the experiment, each bird was given many opportunities to exchange its bread pieces with a human trainer. Another bird looked on, but couldn't participate. In some sessions, the participating bird interacted with a person who always gave them cheese in exchange for their bread. In other sessions, they interacted with a person who took their bread but ate the cheese themselves—an unfair exchange.

Later, the researchers tested whether the birds would show a preference for the person who had always been fair in their interactions. A month later, eight of the nine birds chose to trade with the experimenter who had previously shown themselves to be fair in their interactions over an experimenter who had cheated them in the past (the ninth chose a third, neutral experimenter). However, this only applied to the birds’ first-hand experiences. The birds who observed another bird’s fair or unfair interactions as a third party did not seem to remember who could be trusted and who could not.

Considering crows’ abilities to remember the people who slight them, it’s not terribly surprising that their raven cousins would be able to, too. Nor is it their only complex skill: Corvids can also use tools and practice self-control. Both of which should worry you if you make a habit of making ravens and crows mad.

[h/t The Verge]

The Tiger Who Came to Tea … In the Middle of Rural Yorkshire

If you lived in Holmfirth, England, in the 1940s, there's a good chance you would've found a tiger like this one wandering around town.
If you lived in Holmfirth, England, in the 1940s, there's a good chance you would've found a tiger like this one wandering around town.
photoguru81/iStock via Getty Images

According to the World Wildlife Fund, there are more tigers in captivity than there are in the wild. This is especially true in the United States, where backyard zoos and cub petting operations are successful—if controversial—businesses. Big cat ownership is more heavily regulated in the UK than it is in the U.S., but that wasn’t always the case. More than 70 years ago, there was at least one pet tiger living in England.

To the people of Britain, Holmfirth, 20 miles outside of Manchester, is probably best known as the picturesque setting of Last of the Summer Wine, the BBC show that ran for a staggering 37 years from 1973 to 2010 and is now appropriately credited as being the world’s longest running sitcom. But back in the early 1940s, the village was known locally as the home of Fenella the Holmfirth Tiger.

Fenella’s story actually begins more than 8000 miles away in South Africa, where she was adopted by a family of circus performers and acrobats from Yorkshire, the Overends, in the late 1930s. While touring South Africa with a traveling circus in 1939, the Overend family was offered two newborn circus tiger cubs to rear and eventually incorporate into their act. One of the cubs died barely a week later, but the other—given the name Fenella, or “Feney” for short—survived.

The Overends were forced to return to England after the outbreak of the Second World War. They took Fenella home with them to live (albeit after a brief stay in quarantine) in the back garden of their house in Holmfirth. Although she had a specially built hut and enclosure, the tiger eventually began spending just as much time in the family house as she did in the garden, and according to her owners, soon became extraordinarily tame.

The family would take her for walks through the village, including past the local primary school, where she became a firm favorite among the pupils. When the local council began to raise questions over just how tame Fenella really was, the sight of her walking calmly while being petted by all the schoolchildren as they returned from their lunch break was all it took to quash their worries.

Holmfirth viewed from the cemetery
Holmfirth in the 21st century, with nary a tiger in sight.

Tim Green, Flickr // CC BY 2.0

Fenella was sometimes permitted to run in the fields around the village, where she reportedly made friends with a local cart horse—which is surprising, given she was raised on a diet of horse meat and fish (fish and chips were one of her favorite treats). She apparently also had a fondness for climbing trees to take a nap, and supposedly had a habit of dropping down from the branches and, fairly understandably, surprising passersby. But soon the sight of a fully grown 9-foot Sumatran tigress casually idling her way through the village’s cobbled streets became the norm for the people of Holmfirth.

Fenella was intended to be a performing tiger. Similar to the cub petting operations that still exist in the U.S., visitors could pay sixpence to sit and pet her while the family was on tour. She was also worked into the family’s circus performances by staging a mock wrestling match with her owner. But though the Overends put the big cat to work, they considered her a beloved family pet rather than just another part of their act.

Sadly, Fenella died of a kidney infection during one of the family’s tours in 1950 when she was just over 10 years old. She was buried in the neighbor’s garden, which was said to be one of her favorite hunting grounds. Fenella is still remembered fondly in and around Holmfirth. In 2016, she was a highlight of the Holmfirth Arts Festival, which celebrated the cat’s life with an exhibition of photographs and archival footage of her and the Overend family. Exotic pets might not have remained as popular in the UK as they once were, but Fenella’s popularity at least remains intact.

Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

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