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Christian Grill, Wikimedia Commons // CC BY-SA 3.0
Christian Grill, Wikimedia Commons // CC BY-SA 3.0

In a First for Fish, Needlefish Attack Prey from the Air

Christian Grill, Wikimedia Commons // CC BY-SA 3.0
Christian Grill, Wikimedia Commons // CC BY-SA 3.0

Off the east coast of Australia, fish are doing something funny. On two separate occasions, biologist Ryan Day has seen needlefish employ a novel hunting tactic, launching themselves out of the water and attacking their prey from the air. 

As far as he knows, Day says, “this is the first report of a fish leaping from the water to facilitate predation on other fishes.”

Needlefish, also known as Long Toms, live up to their name. They’re long and slender, and have long jaws lined with plenty of sharp teeth. They live and feed close to the water’s surface and are known for leaping out of the water to make quick escapes from their predators. They can launch out of the water at around 40 miles per hour and even skitter across the surface on their tails. Day says the fishes’ “proclivity for going airborne has resulted in severe injury and even death to people struck by needlefishes” while boating or swimming.

While watching needlefish hunt small baitfish around Australia’s Heron Island, Day saw the fish put these leaps to another use. After stalking their prey and moving in on them slowly, some of the needlefish proceeded with what’s considered their typical approach, swimming through the school of baitfish and then lunging through the water at a targeted fish.

Other needlefish, though, took a different tack. As Day and his colleagues report in the Journal of Fish Biology, as the needlefish neared their prey, they made a “leaping attack,” jumping out of the water and plunging back in right in the middle of the baitfish school, where they nabbed a fish in their jaws. These leaping attacks weren’t flukes: They accounted for half of the attacks the researchers observed.

The researchers saw the same thing while doing field work in another spot near North Stradbroke Island. Here, the needlefish made their leaps from the breaking fronts of waves, the team writes, “appearing to use the energy of the waves to propel them forward.”

The biologists think there are a few reasons needlefish might take to the air to make their attacks. First, the method extends the range they’re able to strike from. Needlefish typically lunge at their targets from around 1.5 feet away. At Heron Island, the fish started their leaping attacks when they were six feet away from the targets, increasing their attack range fourfold. This lets them strike sooner and from farther away, giving their prey less time to see them and escape. 

Aerial attacks also rob the prey of an escape path. When needlefish attack while in the water, the scientists saw, their prey often flee like the needlefish themselves do, leaping out of the water and skittering across the surface. Attacks from above cut the baitfish off from this route, though, and force them to scatter and swim deeper.

It’s also possible that the needlefish are jumping out of the water to hide from their targets. Because of the way light bends as it moves from air to water, a fish’s view of the sky when it looks up at the surface is condensed into a tight circle, creating an "optical manhole" effect known as Snell’s Window. Outside the window, things appear dark or mirror the ocean’s depths or floor. An object in the sky directly above the fish would be pretty clearly visible and appear at full size, the researchers explain, but an object at the boundary of Snell’s Window would appear smaller, dimmer and even blurry or broken up. To a fish, these objects would look farther away than they really are, or might be hard to see at all. The researchers think that the needlefish may be taking advantage of this effect, and jumping into the air to disappear from their prey’s sight right before an attack.

Needlefish aren’t the only fish to use Snell’s Window—or the open sky—to their advantage. Their cousins the flying fish are well known for leaping out of the water and launching themselves at shallow angles to hide from predators on the edges of the optical manhole. And while needlefish are the first to use aerial attacks on prey in the water, other fish sometimes leap out of the water to grab prey in the air. Just last year, scientists in South Africa documented tigerfish leaving the water to attack birds mid-flight.

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Animals
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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