National Geographic Tales of the Weird

by David Braun

  Alligators-Only Singles Club

  The endangered Chinese alligator has quite the set of vocal chords, and researchers believe they have discovered the reason why: The alligators “sing” in order to form singles clubs. In describing the reptilian tunes, a co-author of the study, Xianyan Wang, said, “It sounds like thunder and can travel a long distance.” He thought that the songs might be a way for males to attract females, which is usually the case with other animals. Wang and his team found, however, that both male and females reacted similarly to the calls of either gender, which suggests that the singing is a way of finding other alligators so that mating groups can be formed.

  Alligator Baby-Daddies

  Over the ten-year period, Lance and colleagues took eggs from a total of 92 alligator clutches—or groups of eggs—and hatched 1,802 babies in the laboratory. “You actually peel the eggshell as they’re coming out—they’re really quite cute,” Lance said.

  The team also captured ten female alligators at their nests, drew blood samples, and compared the wild adults’ genes with those of the lab-born hatchlings. No male alligators were captured for the study. But knowing the genes of mother and offspring enabled the scientists to piece together the fathers’ genes.

  The team found that an average of 51 percent of the clutches contained eggs from multiple fathers. But within that number, 87 percent of the clutches had an “obvious” primary male responsible for siring at least half of the babies.

  No one knows why female alligators stand by their “men,” though it could be for the guarantee of healthy babies, Lance said. “If a female is successful with a certain male, why not stay with him?” she said.

  TRUTH:

  ALLIGATORS’ EGGS HATCH MALE BABIES IN HOT TEMPERATURES AND FEMALE BABIES IN COOLER TEMPERATURES.

  Alligators Do It Like Birds?

  The newfound alligator behavior dovetails with the mating habits of birds, the study authors noted. Like alligators, a female bird will pair with a male, then sneak out for liaisons with other males, Lance said.

  Referring to birds’ apparent dinosaur ancestry, Lance said that “if you think about birds really being modern reptiles in a lot of ways, this suggests that perhaps that behavior we see in birds is more ancient.” It also shows that when it comes to sexual behavior, “what you see on the surface is not usually what’s going on.”

  BAMBOO DIET

  How do Giant Pandas Survive?

  A new analysis of panda poop has finally answered an age-old question: How do giant pandas survive on a diet that’s 99 percent bamboo when they have the guts of carnivores?

  Panda Particulars

  1. Pandas spend about 12 hours a day eating.

  2. Pandas’ front paws have enlarged wrist bones that act as thumbs for gripping.

  3. The Chinese name for panda is daxiongmao, which means “large bear-cat.”

  Plant-eating animals tend to have long intestines to aid in digesting fibrous material, a trait the black-and-white bears lack. What’s more, when the giant pandas genome was sequenced in 2009, scientists found that it lacks the genes for any known enzymes that would help break down the plant fibers found in bamboo and other grasses.

  This led researchers to speculate that panda intestines must have cellulose-munching bacteria that play a role in digestion. But previous attempts to find such bacteria in panda guts had failed.

  Dropped Clues

  The new study looked at gene sequences in the droppings from seven wild and eight captive giant pandas—a much bigger sample than what was used in previous panda-poop studies, said study leader Fuwen Wei, of the Chinese Academy of Science’s Institute of Zoology in Beijing.

  A giant panda munches on bamboo. (Photo Credit 3.16)

  Wei and colleagues found that pandas’ digestive tracts do in fact contain bacteria similar to those in the intestines of herbivores. Thirteen of the bacteria species that the team identified are from a family known to break down cellulose, but seven of those species are unique to pandas.

  “We think this may be caused by different diet, the unique inner habitat of the gut, or the unique phylogenetic position of their host,” since pandas are on a different branch of the tree of life than most herbivores, Wei said.

  The Humans Did It!

  Even with help from gut bugs, pandas don’t derive much nutrition from bamboo—a panda digests just 17 percent of the 20 to 30 pounds (9 to 14 kilograms) of dry food from bamboo it eats each day This explains why pandas also evolved a sluggish, energy-conserving lifestyle.

  So how and why did pandas became plant-eaters in the first place? Some scientists theorize that, as the ancient human population increased, pandas were pushed into higher altitudes. The animals then adopted a bamboo diet so they wouldn’t compete for prey with other meat-eaters, such as Asiatic black bears, in their new homes, said Nicole MacCorkle, a panda keeper at the Smithsonian’s National Zoo in Washington, D.C. Pandas will eat meat if it’s offered to them, MacCorkle added, but they won’t actively hunt for it.

  FANGED TADPOLES

  “Vampire” Frog

  Found in Vietnam

  In the treetops of southern Vietnam lives a mysterious tree frog, whose tadpoles are born with black hooked fangs.

  The mountain jungles of Vietnam are home to a new breed of “vampire”—a “flying” tree frog dubbed Rhacophorus vampyrus. First found in 2008, the 2-inch-long (5-centimeter-long) amphibian is known to live only in southern Vietnamese cloud forests, where it uses webbed fingers and toes to glide from tree to tree.

  Adults deposit their eggs in water pools in tree trunks, which protects their offspring from predators lurking in rivers and ponds. “It has absolutely no reason to ever go down on the ground,” said study leader Jodi Rowley, an amphibian biologist at the Australian Museum in Sydney.

  TRUTH:

  THE WORLD’S BIGGEST FROG IS THE SIZE OF A HOUSE CAT.

  Fanged Offspring

  However, that trick isn’t what earned the species its bloodsucking name. Rather, it’s the strange curved “fangs” displayed by its tadpoles, which the scientists discovered in 2010.

  “When I first saw them by looking through a microscope, I said, ‘Oh my God, wow,’ ” said Rowley, whose research is funded in part by the National Geographic Society’s Conservation Trust.

  Tadpoles normally have mouthparts similar to a beak. Instead, vampire frog tadpoles have a pair of hard black hooks sticking out from the undersides of their mouths—the first time such fangs have been seen in a frog tadpole.

  The newly discovered “vampire frog” species in Vietnam (Photo Credit 3.17)

  What Are Fangs For?

  The scientists do not yet know what purpose the fangs serve. However, frogs that raise tadpoles in tree-trunk water holes often feed their young by laying unfertilized eggs as meals. The fangs, Rowley speculated, could help in slicing these open.

  SECRET LANGUAGE OF STRIPES

  These Stripes Say Stay Away!

  Skunks, badgers, wolverines: A recent study shows these animals’ bold color patterns send a powerful message: Danger Ahead!

  A skunk’s stripes aren’t just for style: They may direct predators’ eyes straight to the source of the animal’s smelly anal spray, which helps tell them to “Stay away!”

  A new analysis of data on and pictures of nearly 200 carnivorous mammals—including skunks, badgers, and wolverines—shows that fierce fighters tend to be more boldly colored than more peaceable animals, which tend to use camouflage to stay safe. And those colorations depend on the animals’ methods of defense.

  TRUTH:

  SKUNKS HAVE STRIPED SKIN UNDER THEIR FUR.

  Real Stinkers, True Biters

  Creatures such as skunks, which have long stripes down their body, “tend to be really good at spraying their anal gland secretions—not just dribbling them out,” said study leader Ted Stankowich, a biologist at the University of Massachusetts, Amherst. Skunks are known to eject their offensive musk as far as about 10 feet
(3 meters).

  Other “species that are pretty good at [spraying]—they may not have pure stripes, but their blotches sort of form a stripe down the body.”

  On the other end, badgers—which bite attackers—often have stripes by their mouths. “We think these stripes may guide predators’ attention to the source of danger,” said Stankowich. “If you’re a badger and your mouth is the source of danger, that’s what you want to advertise.”

  Bold Colors an Alternative to Stinky Spray?

  Warning coloration is more typically found in insects, reptiles, and amphibians, such as poison dart frogs. But it is a useful tactic for mammals as well. This nonconfrontational technique for thwarting predators is especially useful for skunks, which prefer not having to spray. Spraying is “costly … they’re depleting a weapon, using ammunition that might be useful, and it advertises where they are,” Stankowich said.

  The stripe “strategy” has been a successful one for skunks throughout evolutionary time, Stankowich said, as the same striped pattern has independently evolved multiple times in skunks and related species across the globe.

  The zorilla, for example, can spray like a skunk but lives in Africa and is more closely related to weasels than skunks. Yet its fur is striped just like a skunk’s, leading the researchers to conclude that the stripes are a good predator deterrent—as is, of course, the ability to spray.

  Like skunks, most other mammalian predators use anal gland secretions, but generally in smaller doses to mark territory, Stankowich noted. (Humans and primates lack anal glands.) Skunks and other sprayers, though—finding themselves with a surplus of musk—“may have co-opted it for use as a defense.”

  Say It, Don’t Spray It: Facts About Skunk Sprays

  1. A skunk’s spray can travel as far as 10 feet (3 meters).

  2. Skunks have a limited supply of defensive spray—they can spray only five to eight times before needing to regenerate more.

  3. The spray of skunks smells musky, is oily, and is amber colored.

  4. The spotted skunk performs a handstand while spraying.

  5. Spraying is actually a skunk’s last resort—it initially tries to scare off a possible threat by stomping its feet and raising its tail.

  EUREKA!

  Elephant Makes a Stool

  First Aha! Moment for Species!

  A seven-year-old elephant’s sudden burst of insight may redefine elephant intelligence.

  In an apparent flash of insight, a young Asian elephant in a zoo turned a plastic cube into a stool—and a tool—a new study says. That eureka moment is the first evidence that pachyderms can run problem-solving scenarios in their heads, then mentally map out an effective solution, and finally, put the plan into action, researchers say.

  An Elephant Never Forgets

  In 1999, Carol Buckley, founder of the Elephant Sanctuary in Tennessee, reported that resident elephant Jenny and new addition Shirley became excited when they first met. “Shirley started bellowing, and then Jenny did, too. Both trunks were checking out each other’s scars. I’ve never experienced anything that intense without it being aggression,” said Buckley. She later discovered that the pair had both performed with the traveling Carson & Barnes Circus—23 years earlier!

  Problem-Solving Pachyderm

  During the study, seven-year-old Kandula was eager to reach a cluster of fruit attached to a branch that was suspended from a wire, just out of reach. After some apparent thought, the young male rolled a large plastic cube under the branch and stepped up to snatch the treat with his trunk—a feat he repeated several times during multiple days with the cube and with a tractor tire.

  The youngest elephant at the National Zoo in Washington, D.C., Kandula had never before been observed moving an object and standing on it to obtain items, and he didn’t arrive at his solution by trial and error, said study co-author Diana Reiss, who studies animal intelligence in elephants and dolphins at Hunter College at City University in New York.

  Only a few species—such as humans, crows, and chimpanzees—have demonstrated spontaneous insight, the ability to suddenly, mentally figure out the solution to a physical problem, Reiss said.

  TRUTH:

  ELEPHANTS, ALONG WITH HUMANS, GREAT APES, AND BOTTLENOSE DOLPHINS, ARE THE ONLY ANIMALS THAT CAN RECOGNIZE THEIR OWN REFLECTIONS.

  No Blocked Nasal Passages

  Researchers gave Kandula various objects that could have been used to reach the fruit, including sticks that he could have grasped with his trunk to knock the snacks down. That Kandula didn’t do this initially puzzled the scientists, until they realized that using sticks in this way would be unnatural for elephants.

  Elephants are known to use sticks as tools—as back scratchers, for example—but not when foraging. That’s because the mammals rely heavily on the trunks’ sense of smell and touch when seeking out food. Holding anything in their trunks would prevent them from effectively feeling and sniffing out dinner, the researchers say.

  “It’s as if your eyes were in the palm of your hand and I said, ‘Pick up this tool and go get that thing.’ As soon as you did that, you’d lose your primary sense,” explained study co-author Preston Foerder of the City University of New York.

  Elephant’s “Sudden Revelation”

  For several sessions, Kandula just stared at the hanging fruit, ignoring the stick as well as the cube that was nearby. “He did not attempt to use a tool to reach the food for seven 20-minute sessions on seven different days,” Hunter College’s Reiss said.

  Kandula, an Asian elephant, uses his step stool at the zoo, in Washington, D.C. (Photo Credit 3.18)

  “And then he finally had what looked to be this sudden revelation, and he headed right over to the block, pushed it in a direct line right underneath the fruit, and stepped right up on it and got the food in one swift movement. “We can’t get inside their heads … but the fact that he immediately went over to the block suggests that he was imagining [the process] ahead of time,” Reiss said.

  Primatologist Frans de Waal agreed. “In order to go to another place to go find a tool that is not visibly near the goal, the elephant needs to imagine what he needs, know where to find it, move away from the goal he wants to reach, in order to find the tool, and so on—all of which goes far beyond the usual learning patterns of most animals,” said de Waal, of the Yerkes Primate Center at Emory University, in an email.

  The finding “is further proof that elephants are right up there with other large-brained animals when it comes to cause-effect understanding and mental problem solving,” added de Waal, who wasn’t part of the study.

  TRUTH:

  ELEPHANTS CAN USE THEIR TRUNKS AS SNORKELS.

  Smarter Than the Average Elephant?

  Two older elephants were also tested, but they failed to show the same kind of insightful thinking. “Perhaps they didn’t care enough to try to get the fruit, or it could have been age-related,” Hunter College’s Reiss said.

  To be fair, Kandula is an exceptionally inquisitive and intelligent elephant, study co-author Don Moore said. “Among the smart elephants—and all elephants are smart … we think Kandula is one of the smarter ones,” said Moore, associate director for animal-care sciences at the National Zoo.

  Moore said he hopes the discovery will help raise awareness about the plight of Asian elephants, which are endangered. “Studies like this can help people relate more closely to animals because it makes them more like us,” he said. “If we can empathize with animals, we are more likely to help conserve them.”

  COLOSSAL CROC!

  Biggest Crocodile Ever Caught?

  It took a village. It took three weeks. And they brought it back, alive.

  In September 2011, the biggest crocodile reportedly ever caught in the Philippines—perhaps the world—was captured alive. The Associated Press reported that the animal was a 21-foot-long (6.4-meter-long) saltwater crocodile.

  Villagers threw a fiesta to celebrate the capture of the croc, which a hundred p
eople had to pull by rope from a creek to a clearing, according to the Associated Press. The 2,369-pound (1,075-kilogram) animal was suspected of attacking several people and killing two. The animal, named Lolong, survived capture and was held in the village of Consuelo, near Bunawan township.

  Edwin Cox Elorde, mayor of Bunawan township in the Philippines, stretches his arms over the huge saltwater crocodile. (Photo Credit 3.19)

  “Crocodiles learn quickly … They particularly learn to avoid dangerous situations very quickly. For research purposes, we find that we often have to change capture techniques, because it’s very hard to catch them with the same trick twice.”

  James Perran Ross

  crocodile researcher, Florida Museum of Natural History

  How Big Is It?

  Federal wildlife officials are trying to confirm whether the reptile is the largest crocodile ever captured. Guinness World Records lists a 17.97-foot-long (5.48-meter-long), Australian-caught saltwater crocodile as the largest in captivity. Yet herpetologist Brady Barr said, “I’d be surprised if it was truly six meters,” adding that a scientist would need to verify the claim.

  Alligator biologist Allan Woodward agreed. “There’s never been a crocodile longer than approximately 18 feet [5.5 meters],” said Woodward, of the Florida Fish and Wildlife Conservation Commission. “That would be an exceptional jump.”