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Timothy Knepp, U.S. Fish and Wildlife Service via Wikimedia Commons // Public Domain
Timothy Knepp, U.S. Fish and Wildlife Service via Wikimedia Commons // Public Domain

Scientists Say Light Colors Make Salmon More Belligerent

Timothy Knepp, U.S. Fish and Wildlife Service via Wikimedia Commons // Public Domain
Timothy Knepp, U.S. Fish and Wildlife Service via Wikimedia Commons // Public Domain

Marketers have long known the power of color to manipulate consumers. Red and yellow supposedly make us hungry, while blue can calm us down. Apparently, we’re not alone in our subconscious response to color; scientists say salmon kept in tanks with black backgrounds were four times less aggressive than those in light blue tanks. The findings were published last week in the journal PLOS ONE.

Fish consumption is on the rise, and a lot of that demand is met by a growing aquaculture (fish farming) industry. But even as consumers begin to demand beef and eggs from humanely raised cows and chickens, few have given fish welfare much thought.

Fortunately, scientists have. A large body of research indicates that fish are incredibly visual animals and are very sensitive to the appearance of their environments. Previous studies have shown that even the colors of gravel and light filtering through the water can affect fish health, fertility, and aggression. But nobody had considered the potential influence of background color until researchers from the University of British Columbia’s Animal Welfare Program decided to take a look.

The scientists brought in 100 Coho salmon (Oncorhynchus kisutch) and divided them into 10 tanks of 10 fish. Every day, each tank was lined with a piece of laminated paper divided into two different colors: either black with white, light gray, dark gray, or a pattern; and light blue with white, light gray, dark gray, or black. This way, the fish could swim to the side of the tank backed with the color they liked better. Each tank was equipped with a camera that filmed the salmon from above. Afterward, the researchers watched each tape and recorded how the fish behaved, as well as how many fish chose each color.

The salmon had very clear preferences. Time and time again, they opted to stay in front of the darkest background available. When they could have black, they chose black; in the absence of black, they settled for dark gray. And even when they weren’t on the darker side of the tank, just having a black or gray section in the tank seemed to soothe the fish.

The reverse was also true. Like Morticia Addams, the salmon seemed almost offended by pastels. When the fish were forced to endure light blue backgrounds they became four times more aggressive than they were in black-backed tanks, chasing, charging, and even biting their tank-mates.

Why does this matter? Well, guess what color is currently the default for salmon fishery tank backgrounds. Did you guess light blue? You’re right.

The researchers note that their study had some limitations. The fish they studied were all the same age, and a salmon’s aggressive tendencies do vary over its lifespan. They also didn’t test the effects of water temperature and season. Still, this is progress towards a better understanding.

“Fish both preferred and were dramatically less aggressive in darker backgrounds,” co-author Marina Keyserlink said in a press statement. “Thus, we found a relatively simple environmental modification that has the potential to improve animal welfare."

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Pigeons Are Secretly Brilliant Birds That Understand Space and Time, Study Finds
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Of all the birds in the world, the pigeon draws the most ire. Despite their reputation as brainless “rats with wings,” though, they’re actually pretty brilliant (and beautiful) animals. A new study adds more evidence that the family of birds known as pigeons are some of the smartest birds around, as Quartz alerts us.

In addition to being able to distinguish English vocabulary from nonsense words, spot cancer, and tell a Monet from a Picasso, pigeons can understand abstract concepts like space and time, according to the new study published in Current Biology. Their brains just do it in a slightly different way than humans’ do.

Researchers at the University of Iowa set up an experiment where they showed pigeons a computer screen featuring a static horizontal line. The birds were supposed to evaluate the length of the line (either 6 centimeters or 24 centimeters) or the amount of time they saw it (either 2 or 8 seconds). The birds perceived "the longer lines to have longer duration, and lines longer in duration to also be longer in length," according to a press release. This suggests that the concepts are processed in the same region of the brain—as they are in the brains of humans and other primates.

But that abstract thinking doesn’t occur in the same way in bird brains as it does in ours. In humans, perceiving space and time is linked to a region of the brain called the parietal cortex, which the pigeon brains lack entirely. So their brains have to have some other way of processing the concepts.

The study didn’t determine how, exactly, pigeons achieve this cognitive feat, but it’s clear that some other aspect of the central nervous system must be controlling it. That also opens up the possibility that other non-mammal animals can perceive space and time, too, expanding how we think of other animals’ cognitive capabilities.

[h/t Quartz]

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The Queen's Racing Pigeons Are in Danger, Due to an Increase in Peregrine Falcons
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Queen Elizabeth is famous for her love of corgis and horses, but her pet pigeons don't get as much press. The monarch owns nearly 200 racing pigeons, which she houses in a luxury loft at her country estate, Sandringham House, in Norfolk, England. But thanks to a recent boom in the region’s peregrine falcon population, the Queen’s swift birds may no longer be able to safely soar around the countryside, according to The Telegraph.

Once endangered, recent conservation efforts have boosted the peregrine falcon’s numbers. In certain parts of England, like Norfolk and the city of Salisbury in Wiltshire, the creatures can even find shelter inside boxes installed at local churches and cathedrals, which are designed to protect potential eggs.

There’s just one problem: Peregrine falcons are birds of prey, and local pigeon racers claim these nesting nooks are located along racing routes. Due to this unfortunate coincidence, some pigeons are failing to return to their owners.

Pigeon racing enthusiasts are upset, but Richard Salt of Salisbury Cathedral says it's simply a case of nature taking its course. "It's all just part of the natural process,” Salt told The Telegraph. "The peregrines came here on their own account—we didn't put a sign out saying 'room for peregrines to let.' Obviously we feel quite sorry for the pigeons, but the peregrines would be there anyway."

In the meantime, the Queen might want to keep a close eye on her birds (or hire someone who will), or consider taking advantage of Sandringham House's vast open spaces for a little indoor fly-time.

[h/t The Telegraph]

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