Ravens Can Figure Out When Someone Is Spying on Them

Jana Mueller
Jana Mueller

Corvids, the family of birds that includes crows and ravens, are canny beasts. They've been known to exercise self-control, count, hold grudges, and more. Now, new research suggests they possess at least a rudimentary Theory of Mind—the ability to attribute mental states to others.

A study in Nature finds that ravens can tell when someone else can see them, guarding their food when a peephole to their cache is open. While previous research suggested that birds might have an awareness of other animals' mental states, the results have been inconclusive. The Nature study is evidence that corvids can do more than just track other birds' gaze; they may understand the concept of "seeing."

Vienna-based researchers set up two rooms separated by windows that could be closed with covers. These covers had peepholes in them that could also be opened or closed. First, the 10 ravens were each allowed to cache food, while other birds were in the next room and the windows were open or closed. Then, they were trained to look through the peepholes to find food in the other room, so that they knew that the holes could be used to see through the window covers. Afterwards, each of the ravens was again presented with food with one of the two peepholes open. The adjacent observation room didn't have any birds in it, but the researchers played the sounds of another raven recorded during one of the previous trials.

When the birds heard the sounds of another raven in the next room, and the peephole was open, the birds behaved as if they knew they were being watched—they hid their cache of food quickly and didn't add more food to it as often, as if they knew that it might be compromised. However, they behaved normally when the peephole was closed.

This suggests that ravens don't just track their competitors' gaze to know when they’re being watched, but can infer from past experience when they can be seen.

No Venom, No Problem: This Spider Uses a Slingshot to Catch Prey

Courtesy of Sarah Han
Courtesy of Sarah Han

There are thousands of ways nature can kill, and spider species often come up with the most creative methods of execution. Hyptiotes cavatus, otherwise known as the triangle weaver spider, is one such example. Lacking venom, the spider manages to weaponize its silk, using it to hurl itself forward like a terrifying slingshot to trap its prey.

This unusual method was studied up close for a recent paper published in the Proceedings of the National Academy of Sciences by researchers at the University of Akron in Ohio. They say it's the only known instance of an animal using an external device—its web—for power amplification.

Hyptiotes cavatus's technique is simple. After constructing a web, the spider takes one of the main strands and breaks it in half, pulling it taut by moving backwards. Then, it anchors itself to a spot with more webbing in the rear. When the spider releases that webbing, it surges forward, propelled by the sudden release of stored energy. In the slingshot analogy, the webbing is the strap and the spider is the projectile.

This jerking motion causes the web to oscillate, tangling the spider's prey further in silk. The spider can repeat this until the web has completely immobilized its prey, a low-risk entrapment that doesn’t require the spider to get too close and risk injury from larger victims.

The triangle weaver spider doesn’t have venom, and it needs to be proactive in attacking and stifling prey. Once a potential meal lands in its web, it’s able to clear distances much more quickly using this slingshot technique than if it crawled over. In the lab, scientists clocked the spider’s acceleration at 2535 feet per second squared.

Spiders are notoriously nimble and devious. Cebrennus rechenbergi, or the flic-flac spider, can do cartwheels to spin out of danger; Myrmarachne resemble ants and even wiggle their front legs like ant antennae. It helps them avoid predators, but if they see a meal, they’ll drop the act and pounce. With H. cavatus, it now appears they’re learning to use tools, too.

[h/t Live Science]

Plano, Texas Is Home to a Dog-Friendly Movie Theater That Serves Bottomless Wine or Whiskey

K9 Cinemas
K9 Cinemas

For dog owners in Plano, Texas, movie night with Fido no longer just means cuddling on the couch and browsing Netflix. The recently opened K9 Cinemas invites moviegoers—both human and canine—to watch classic films on the big screen. And the best part for the human members of this couple? Your $15 ticket includes bottomless wine or whiskey (or soft drinks if you're under 21).

The theater operates as a pop-up (or perhaps pup-up?) in a private event space near Custer Road and 15th Street in Plano. Snacks—both the pet and people kind—are available for $2 apiece. Dogs are limited to two per person, and just 25 human seats are sold per showing to leave room for the furry guests.

Pet owners are asked follow a few rules in order to take advantage of what the theater has to offer. Dogs must be up-to-date on all their shots, and owners can submit veterinary records online or bring a hard copy to the theater to verify their pooch's health status. Once inside, owners are responsible for taking their dog out for potty breaks and cleaning up after any accidents that happen (thankfully the floors are concrete and easy to wipe down).

While many of the movies shown are canine-themed—a recent screening of A Dog's Journey included branded bandanas with every ticket purchase—they also hold special events, like a Game of Thrones finale watch party (no word on how the puppers in attendance responded to Jon Snow finally acknowledging what a good boy Ghost is).

SECTIONS

arrow
LIVE SMARTER