7 Things You Might Not Know About Impalas

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iStock

Impalas have been the inspiration for cars and musicians, but the animal itself has never received much attention in popular culture—at least not in the way some like hedgehogs, raccoons, or otters have. Read on to learn seven facts about some of the most jumpy creatures on the African savanna (in more ways than one).

1. THEY CAN LEAP MORE THAN THREE TIMES THEIR HEIGHT.

image of an adult male impala leaping across some water
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According to National Geographic, impalas can leap up to 10 feet in the air and travel as far as 33 feet in a single bound—which, for an animal with an average height of 3 feet and length of around 4 feet, is a considerable distance. This agility makes it easy for impalas to maneuver over and around obstacles, which comes in handy when they need to escape predators.

2. THEY'RE KNOWN TO CRY WOLF.

image of a herd of impalas running alongside some zebras
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Three of the main prey animals on the southern African savanna (impalas, zebras, and wildebeests) can recognize one another's warning cries, according to researchers from the University of Minnesota. That works to everyone's advantage if a predator is close. If a zebra, for instance, sounds a warning call, then any nearby zebras, wildebeests, or impalas know to flee.

However, the study found that zebras were more likely to ignore warning calls from impalas, Popular Science reported. That makes sense, as zebras can weigh six times as much as impalas and make for hardier prey. Oddly, wildebeests were more likely to flee the area after hearing a cry from an impala than from another wildebeest. Researchers felt that could be because wildebeests often judged it was safer to move quickly and return in case of a false alarm than stay and risk attack. Impalas themselves, however, were skeptical of calls made by their own kind. According to researcher Meredith Palmer, it's because impalas are naturally anxious and tend to sound false alarms.

"If you're an impala and you know that other impala are probably responding to a predator but there's also a 25 percent chance that they are alarm calling at some waving grass, maybe you would give more weight to an alarm call from something like a zebra which perhaps is a little more discriminatory," Palmer told Popular Science.

3. THERE'S A LONGSTANDING—BUT UNSUBSTANTIATED—THEORY THAT THEY CAN DELAY GIVING BIRTH FOR UP TO A MONTH.

image of two adult female impalas looking after several impala calves
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Impalas in southern Africa are synchronous breeders, meaning they tend to mate and give birth around the same time each year. Impala breeding usually corresponds with the wet season—they usually mate in May, at the end of the wet season, and give birth in November, at the start of it. That predictable breeding schedule usually gives impala calves their best shot at survival. Impalas and other prey face more risk in the dry season, when dwindling food and water supplies force predators and prey toward the same geographic locations.

Rumor has it pregnant impalas can delay giving birth for up to a month if the wet season is late. That belief is probably a fallacy, said Shaun D'Araujo, a writer for Londolozi, a South African hospitality group.

According to D'Araujo, it's possible just as many impala calves are born before the start of the wet season as after it. But it's survival of the fittest on the savanna—calves born just a little too early may die before humans ever know they were there. And on top of that, natural birth for an impala born a month late would be impossible because the offspring would be too large, author Trevor Carnaby points out.

4. THEY'RE THE ONLY MEMBER OF THEIR GENUS.

image of impalas in a striking African sunset
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Impalas are one of a kind. They're the only member of the genus Aepyceros, which is included under the Bovidae family (along with buffalo, sheep, goats, and cows, to name a few). Within the impala species, scientifically known as Aepyceros melampus, there are two subspecies of impalas: the common impala, or Aepyceros melampus melampus, and the black-faced impala, or Aepyceros melampus petersi. These black-faced impalas are considerably rarer and are only found in a small subsection of southern Africa (specifically in Namibia and Angola).

5. THEY'RE A COMMON INGREDIENT IN SOUTH AFRICAN JERKY.

image of slices of South African biltong
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South African biltong is a dried and cured meat often compared to jerky. It's usually made from beef, but some purveyors still produce biltong made from game meats. Potential animals on the biltong menu include impalas, ostriches, and wildebeests.

6. THEY'RE MORE LIKELY TO ESCAPE PREDATORS IF THEY SLOW DOWN, BOB, AND WEAVE.

image of an impala running from a cheetah
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Running as fast as possible isn't the best move for impalas hoping to evade a predator, according to a study published in Nature in February 2018. Cheetahs, for example, have 20 percent more muscle power than impalas, and they can accelerate 37 percent faster. And with a top speed around 60 miles per hour (which is considerably faster than an impala's top speed), a cheetah can easily outstrip an impala in a straightforward race.

The best tactic, researchers say, is to move unpredictably. Animals moving at high speeds are less maneuverable, so impalas can shake off a predator if they change directions rapidly. According to Seeker, lower-speed chases almost always favor prey survival.

7. THEY FORM THEIR OWN CLIQUES.

image of a herd of impalas
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Although impalas tend to be fairly social for most of the year, they break off into subgroups during the rut, or mating season (generally from January to May, depending on the location). Impalas typically form three types of herds: all-female herds (often led by a territorial male who may be replaced multiple times), bachelor herds, and mixed-sex family herds led by territorial males.

All- or mostly-female herds are generally uniform and cohesive. Parent-child bonds dissolve after calves are weaned, so female herds often consist of many unrelated impalas. Female herds can be quite large, consisting of as many as 50 to 100 impalas. In Rwanda's Akagera National Park, the average female herd had 36 impalas.

Male impalas who fail to mate successfully form bachelor herds of five to 30 individuals. Bachelor herds are smaller than both family and female herds, and they tend to consist of what ecologist Deon Furstenburg described as "sexually mature, but socially immature rams."

Male impalas typically only become territorial for about four months of the year, during which time they'll jealously protect their harems of female impalas and calves. If one male impala loses a fight to another, they'll often be forced to surrender their herd and join a bachelor herd instead.

Do Dogs Understand What You’re Telling Them? Scientists Are Scanning Their Brains to Find Out

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iStock/kozorog

We all know that dogs can learn to respond to human words, but it’s not always clear what’s happening in a dog’s brain when they hear and recognize words like “cookie” and “fetch.” Do they have to rely on other clues, like gestures, to figure out what we mean by that word? Do they picture a dog biscuit when you say “cookie,” or just the sensation of eating? In a new study, scientists from Emory University and the New College of Florida tried to get to the bottom of this question by training dogs to associate certain objects with words like “blue” and “duck,” then using fMRI brain scanners to see what was happening in the dogs’ heads when they heard that word.

The study, published in Frontiers in Neuroscience, examined the brains of 12 different dogs of various breeds (you can see them below) that had been trained to associate two different objects with random words like “duck,” “blue,” and “beach ball.” Those two objects, which were different for each dog, were brought by the dogs’ owners from home or chosen from a selection of dog toys the researchers compiled. One object had to be soft, like a stuffed animal, and the other one had to be something hard, like a rubber toy or squeaky toy, to make sure the dogs could clearly distinguish between the two. The dogs were trained for several months to associate these objects with their specific assigned words and to fetch them on command.

Then, they went into the fMRI machine, where they had been trained to sit quietly during scanning. The researchers had the dogs lie in the machine while their owners stood in front of them, saying the designated name for the toys and showing them the objects. To see how the dogs responded to unknown words, they also held up new objects, like a hat, and referred to them by gibberish words.

Dogs in a science lab with toys
Prichard et al., Frontiers in Neuroscience (2018]

The results suggest that dogs can, in fact, discriminate between words they know and novel words. While not all the dogs showed the same neural response, they showed activation in different regions of their brains when hearing the familiar word versus the novel one.

Some of the dogs showed evidence of a greater neural response in the parietotemporal cortex, an area of the dog brain believed to be similar to the human angular gyrus, the region of the brain that allows us to process the words we hear and read. Others showed more neural activity in other regions of the brain. These differences might be due to the fact that the study used dogs of different sizes and breeds, which could mean differences in their abilities.

The dogs did show a surprising trend in their brains’ response to new words. “We expected to see that dogs neurally discriminate between words that they know and words that they don’t,” lead author Ashley Prichard of Emory University said in a press release. “What's surprising is that the result is opposite to that of research on humans—people typically show greater neural activation for known words than novel words." This could be because the dogs were trying extra hard to understand what their owners were saying.

The results don’t prove that talking to your dog is the best way to get its attention, though—it just means that they may really know what's coming when you say, "Want a cookie?"

Scientists Find Fossil of 150-Million-Year-Old Flesh-Eating Fish—Plus a Few of Its Prey

M. Ebert and T. Nohl
M. Ebert and T. Nohl

A fossil of an unusual piranha-like fish from the Late Jurassic period has been unearthed by scientists in southern Germany, Australian news outlet the ABC reports. Even more remarkable than the fossil’s age—150 million years old—is the fact that the limestone deposit also contains some of the fish’s victims.

Fish with chunks missing from their fins were found near the predator fish, which has been named Piranhamesodon pinnatomus. Aside from the predator’s razor-sharp teeth, though, it doesn’t look like your usual flesh-eating fish. It belonged to an extinct order of bony fish that lived at the time of the dinosaurs, and until now, scientists didn’t realize there was a species of bony fish that tore into its prey in such a way. This makes it the first flesh-eating bony fish on record, long predating the piranha. 

“Fish as we know them, bony fishes, just did not bite flesh of other fishes at that time,” Dr. Martina Kölbl-Ebert, the paleontologist who found the fish with her husband, Martin Ebert, said in a statement. “Sharks have been able to bite out chunks of flesh, but throughout history bony fishes have either fed on invertebrates or largely swallowed their prey whole. Biting chunks of flesh or fins was something that came much later."

Kölbl-Ebert, the director of the Jura Museum in Eichstätt, Germany, says she was stunned to see the bony fish’s sharp teeth, comparing it to “finding a sheep with a snarl like a wolf.” This cunning disguise made the fish a fearful predator, and scientists believe the fish may have “exploited aggressive mimicry” to ambush unsuspecting fish.

The fossil was discovered in 2016 in southern Germany, but the find has only recently been described in the journal Current Biology. It was found at a quarry where other fossils, like those of the Archaeopteryx dinosaur, have been unearthed in the past.

[h/t the ABC]

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