Flamingos Apply"Makeup" to Impress Mates

There's a reason why flamingos are so pretty in pink:Thebirdsapply"makeup"to impress mates, a new study says.

Scientists had long assumed that flamingo feathers change color only when the plumage becomes faded by the sun or unintentionally stained by organic materials.

But while studyinggreater flamingosat theDoñana Biological Research StationinSpain, ornithologist Juan Amat realized that something else was going on.

"We noticed that immediately after chicks were hatching, {adult} flamingos lost their pink color,"he said. (See wading-bird pictures.)

Adults later regained their famous pink plumage,"yet they were not moulting, so we wondered if there was something cosmetic to consider."

Flamingos: Beyond the Pale

To examine this hypothesis, the researchers studied seasonal variations in flamingo color at three wetlands in Spain. The team also monitored the birds' breeding, feather maintenance, and courtship activities.

(See National Geographic's backyard bird identifier.)

Using telescopes, the scientists assigned each flamingo a color value based on a scale of one to three, ranging from very pale to vibrant pink.

The team found that the color values dropped from an average of 1.7 in February—the height of the mating season—to an average of 1.0 in May, June, July, August, and September, when the birds were looking after hatchlings. In October the values leapt up again, to 1.6.

Flamingos, like all birds, produce oil in glands near their tails. Birds daub this oil onto their feathers with their beaks.

The oil is well known to improve the longevity of feathers and keep them waterproof. But Amat suspected that the flamingos might also be using the substance for coloration.

Flamingos get their color from compounds called carotenoids, which the birds absorb from their diets of algae and small crustaceans.

Flamingo feathers already contain some carotenoids. But, based on samples collected from captive flamingos, Amat and colleagues found that the oil is especially rich in the compounds.

Flamingos In Fine Feather

Both male and female birds increased their oil-daubing behavior during the mating season, the team noted.

In general, the deeper the pink, the more attractive the bird—so the flamingos were likely applying the oil like makeup to make themselves more desirable, he said.

(Related:"Flashier Great Tits Produce Stronger Sperm, Bird Study Shows.")

"We were so excited to discover this,"Amat said.

"Other birds, like the bearded vulture, are known to take mud baths that leave their feathers tinged with color. We now need to go and look at these species to see if they are applying cosmetics just like the flamingos do."

The flamingo-makeup study appeared online October 23 in the journalBehavioral Ecology and Sociobiology.

forNational Geographic News

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Photos: Best European Wildlife Pictures Announced

A snail moves toward the light in a photograph that won the"Other Animals"category in the2010 European Wildlife Photographer of the Yearcompetition.

The contest, presented annually by the Society of German Nature Photographers, awards photographs in eight different categories as well as the Fritz Pölking Award and Fritz Pölking Junior Award.

(See relatedpictures:"Wild Europe Exposed by Giant Photo Project.")

In 2010, the competition received more than 11,000 entries from more than 29 countries. Entrants had to live in Europe, although their photographs were taken around the world.

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Polar Bears Turning to Goose Eggs to Survive Warming?

Polar bearsmay be turning tosnow gooseeggs to help them survive as Arctic sea ice melts due toglobal warming, scientists say.

Polar bears typically hunt seals out at sea, returning to land when springtime temperatures melt the ice floes the bears use as rest stops. But climate change has been causingsea ice to melt earlier each year (pictures), forcing polar bears to come ashore sooner.

(See"Most Polar Bears Gone By 2050, Studies Say.")

In a previous study, biologistRobert Rockwelland his colleague Linda Gormezano documented polar bears inCanada's Hudson Bay area (map)returning to land about two weeks earlier than they'd done in the past, near the end of June instead of the middle of July.

This early arrival brings the bears back to shore around the same time that nesting snow geese are incubating their eggs in Hudson Bay.

Snow goose eggs are more often food for skuas and Arctic foxes. But polar bears are famous for their voracious appetites: One polar bear reportedly went on a"goose egg-fest,"Rockwell said, devouring more than 800 eggs in four days.

Accounts like this have caused some scientists to worry that hungry polar bears might severely reduce or wipe out nesting snow goose populations.

(Related:"Grizzly Bears Moving Into Canada's Polar Bear Capital.")

But in new research, recently published online in the journalOikos,Rockwell and his team show that the currently plentiful snow goose population is in no danger from the bears. In fact, the eggs might provide a valuable backup food source as polar bears are forced to end their seal hunts early.

For one thing, a snow goose egg is about twice the size of a chicken egg, but it is much more nutritious, said Rockwell, a research associate at theAmerican Museum of Natural Historyand a professor at the City University of New York.

Downing a goose egg is like"eating a stick of butter,"he said. Rockwell estimates that if a polar bear eats about 88 snow goose eggs, the bear will be consuming the caloric equivalent of a seal.

Bears and Geese Will Occasionally"Mismatch"

Snow geese are migratory birds that spend their winters in warmer parts of North America. The birds typically arrive in the Arctic to breed around the end of May and remain through August. (Find out about"Great Migrations"on the National Geographic Channel.)

Millions of snow geese arrive in Canada each year to breed, and each nesting female lays four eggs, on average.

Snow geese are currently considered a species of least concern according to theInternational Union for Conservation of Nature, because they have a wide range and a large global population that seems to be increasing.

Rockwell's initial research suggested polar bears are developing an alarming taste for their new food source. The biologist had even heard reports of some bears coming ashorebeforethe sea ice melts to gorge on goose eggs.

(Also see"Arctic Foxes Put Eggs in 'Cold Storage' for Lean Times.")

The new study, however, indicates that the birds are safe.

Using historical records, Rockwell and his colleagues simulated the timing of four events that occur during the Arctic spring: the break-up of sea ice, the polar bears' migration to shore, the northward migration of snow geese, and the laying of eggs.

The results showed that, even though the two species' time on land will increasingly overlap as global warming continues, there will always be"mismatches"—years when the bears just miss the nesting geese.

"It's just natural {climate} variation,"Rockwell said."It only takes the occasional year of mismatch to allow the goose population to reset itself."

Polar bears are expected to come ashore even earlier in the coming years, so goose eggs could become an increasingly vital food source for them. (See"Polar Bears Listed as Threatened Species in U.S.")

"Bears are bears,"Rockwell said."Once they find a food source, they're going to capitalize on it."

forNational Geographic News

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Rare Pictures: Crocodile Attacks Elephant

A routine trip to the water hole recently resulted in a life-or-death struggle for a pair ofAfrican elephantswhen they were ambushed by a hungryNile crocodile(pictured).

Tourist Martin Nyfeler of Kloten, Switzerland, captured pictures of the wild encounter during a visit toZambia's South Luangwa National Park.

"We saw a mother elephant and baby at the water hole and said {to the guides}, You know, what a cute picture, let's stop here,"Nyfeler told National Geographic News.

"And suddenly the croc jumped out. The whole event took maybe 15 seconds."

—Brian Handwerk

(Explore National Geographic's 360-degree elephant panorama.)

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Sea Turtle Herpes Tumors Linked to Sewage?

Tumors that have plaguedgreen sea turtlesworldwide for decades may be caused bypollution, a new study says.

Nitrogen-rich runoff from sewers and farms is fueling a rise in invasive seaweed that, when consumed by thereptiles, may trigger an otherwise dormant herpes virus. This virus in turn causes the often fatal growths.

The cauliflower-like tumors—which can sprout on a turtle's eyes, mouth, joints, and internal organs—have contributed to declines in the 4-foot-long (1.2-meter-long) turtles. Listed as endangered by the International Union for Conservation of Nature, green sea turtles are found in the world's tropical and subtropical waters. (See sea turtle pictures.)

In some parts ofHawaii, where green sea turtle strandings occur regularly, as many as 90 percent of stranded dead or dying turtles discovered have been afflicted with the disease, according to study leader Kyle Van Houtan, an ecologist with the National Oceanic and Atmospheric Administration'sPacific Islands Fisheries Science Centerin Honolulu.

(Relatedpictures:"Millions of Sea Turtles Killed Accidentally?")

Wherever the turtle strandings occur, there is often evidence of sewage and invasive algae, Van Houtan said.

Until now, however, hard evidence that pollution factors into the turtles' disease has remained elusive, he noted.

Polluted Areas Are Turtle-Tumor Hot Spots

Van Houtan and colleagues analyzed human activities on land to calculate a"nitrogen footprint"for each watershed—an area that drains into a water body—on the Hawaiian islands of Oahu, the Big Island, and Maui (see map). The team also studied 28 years' worth of data on green sea turtle strandings on the islands.

Comparing the two data sets, the scientists found that diseased turtles strand more in areas with high nitrogen runoff from agriculture, sewers, and cities.

(See"Cocaine, Spices, Hormones Found in Drinking Water.")

These turtle-tumor hot spots are"the places that I wouldn't necessarily want to go surfing after a rain… because of the nasty stuff that would show up"in the ocean, Van Houtan added.

Nitrogen Awakens Herpes Viruses

The scientists don't think the nitrogen-loaded runoff causes tumors directly. Instead, there may be a chain of interactions that starts with a nitrogen-fed boom in nonnative seaweed, at least in Hawaii.

Nitrogen acts as a fertilizer in oceans, and is a main cause of oxygen-sucking algae blooms called dead zones.

Around the Hawaiian islands, several seaweed species were either accidentally introduced or deliberately harvested for food crops and later"escaped"cultivation and spread into the wild.

For instance, hookweed—native to the Mediterranean, the Caribbean, the Indian Ocean, and the Philippines—was introduced to Hawaii in 1974. Gorillo ogo and spiny seaweed came from the Pacific and Indian Oceans and Guam, respectively.

(Learn more about marine invasive species.)

The seaweed absorbs the extra nitrogen and converts it into an amino acid—the building block of protein—called arginine. When turtles eat the seaweed, arginine awakens dormant herpes viruses in the turtles' bodies that generate the tumors.

It's possible that nonnative seaweed in Hawaii is better than native seaweed species at converting nitrogen to arginine, Van Houtan noted.

And because Hawaiian green sea turtles now rely on the invasive seaweed for food, Van Houtan suspects the animals get dosed with tumor-triggering amino acids at every meal.

Turtle Tumors Have Other Causes?

Alonso Aguirre, a wildlife epidemiologist with the environmental nonprofit EcoHealth Alliance in New York, praised the study for confirming the link between pollution and sea turtle tumors.

But he also said that the tumors' cause may be more complicated.

The pollution-virus link is"a very simplistic pathway to explain the whole disease,"Aguirre said, adding he suspects other factors, such as water temperature, and possibly additional viruses, are at play.

Regardless of exactly how the tumors form, Aguirre said the study shows that"the turtles… are telling us that something is happening to the oceans in a way that now, we have to pay attention."

Turtle-tumor research published September 29 in the journalPLoS ONE.

forNational Geographic News

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Cricket Has World's Biggest Testicles (But Puny Output)

The new title for world's biggest testicles (relative to body weight) goes to the tuberous bushcricket, a type of katydid, according to a new study.

The sperm-producing organs account for 14 percent of the body mass of males of this bushcricket species. The previous record holder's testicles—belonging to the fruit flyDrosophila bifurca—tipped the scales at about 11 percent of its body mass.

"I was amazed by the size of the testes—they seemed to take up the entire abdomen,"said study leaderKarim Vahed, a behavioral ecologist at the University of Derby in the U.K.

But the new heavyweight champion doesn't pack much of a punch. The team was surprised to discover that tuberous bushcrickets have smaller ejaculations than bushcricket species with smaller testicles.

Bigger Testicles, More Sperm Supply?

For the testicle study, Vahed and colleagues dissected specimens from 21 bushcricket species, collected around Europe.

Theinsectsare ideal for studying reproductive evolution because of their efficient mating process, Vahed noted.

For one thing, the male bushcricket transfers his sperm to the female in a"neat packet"that's easily retrievable by researchers—"whereas in mammals, you'd have to provide some sort of condom to measure the ejaculate,"he said.

Likewise the female stores each male's sperm packet in a separate pouch, enabling scientists to count how many times a female has mated in her lifetime. (See insect-egg pictures inNational Geographicmagazine.)

Predictably, the team found that the species whose females mate the most has the males with the biggest testicles, according to the study, published November 10 in the journalBiology Letters.

(See"Bigger Testes Can Offer a Competitive Edge.")

But among the 21 bushcricket species, the study showed that, as testicle size increases, ejaculation volume decreases.

The discovery runs counter to previous findings in other species—especially mammals. Usually the male with the biggest testicles has more sperm in each ejaculation, thus earning him more tickets in the lottery of fertilizing females, Vahed explained.

A possible explanation, he said, is that, in societies with promiscuous females, large testicles give males a more plentiful sperm reservoir for multiple matings. Female tuberous bushcrickets mate an average of 23 times in their two-month life spans.

This alternative explanation for large testicles may even make scientists revisit some of their studies on vertebrates, he added. It's usually the other way around.

"It's clear that insects are one of the major types of organisms on the planet Earth, {but} the tendency is to draw conclusions from studies of vertebrates and generalize them as if they apply to everything,"he said.

Bushcricket Titillator Mystery

Next, Vahed plans to shift his focus to"titillators,"the hard, penis-like part of male bushcricket genitalia that's inserted into the female. These poorly studied—and often spiny—parts may stimulate the female, allow the male to hang on, or both.

(See relatedpictures:"'Torture' Phalluses Give Beetles Breeding Boost.")

And, as it turns out, the tuberous bushcricket isn't quite so well endowed in this arena. The species' parts, he said,"don't seem to be as outlandish as some species that have double sets of spiny titillators."

National Geographic News

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New Self-Cloning Lizard Found in Vietnam Restaurant

You could call it the surprise du jour: A popular food onVietnamesemenus has turned out to be a lizard previously unknown to science, scientists say.

What's more, the newfoundLeiolepis ngovantriiis no run-of-the-millreptile—the all-female species reproduces via cloning, without the need for male lizards.

Single-gender lizards aren't that much of an oddity: About one percent of lizards can reproduce by parthenogenesis, meaning the females spontaneously ovulate and clone themselves to produce offspring with the same genetic blueprint.

(Related:"Virgin Birth Expected at Christmas—By Komodo Dragon.")

"The Vietnamese have been eating these for time on end,"said herpetologistL. Lee Grismerof La Sierra University in Riverside, California, who helped identify the animal.

"In this part of the Mekong Delta {in southeastern Vietnam}, restaurants have been serving this undescribed species, and we just stumbled across it."

(See"New Snub-Nosed Monkey Discovered, Eaten.")

Wild Lizard Chase

Grismer's Vietnamese colleague Ngo Van Tri of theVietnam Academy of Science and Technologyfound live lizards for sale in a restaurant inBa Ria-Vung Tau Province (see map).

Noting that the reptiles all looked strangely similar, Ngo sent pictures to Grismer and his son Jesse Grismer, a herpetology doctoral student at the University of Kansas.

The father-son team suspected that they may be looking at an all-female species. That's because the team knew that the lizard likely belonged to theLeiolepisgenus, in which males and females in lizards have distinct color differences—and no males were apparent in the photos.

So the pair hopped on a plane to Ho Chi Minh City (Saigon), telephoned the restaurant to"reserve"the lizards, and began an eight-hour motorcycle odyssey—which ended in disappointment.

"When we finally got there, this crazy guy had gotten drunk and served them all to his customers,"recalled Lee Grismer, who has received funding for other projects from theNational Geographic Society's Committee for Research and Exploration.(The Society owns National Geographic News.)

Fortunately other area restaurants had the lizards on offer, and local schoolchildren helped gather more from the wild. Eventually the Grismers examined almost 70 of the lizards—and all turned out to be females.

Who's Your (Lizard) Daddy?

The newfound reptile also had rows of enlarged scales on its arms as well as lamellae—bone layers—under its toes that set it apart from other species, according to the study, published April 22 in the journalZOOTAXA.

The species is probably a hybrid from maternal and paternal lines of two related lizard species, a phenomenon that can occur in transition zones between two habitats. For instance, the new lizard's home, the Binh Chau-Phuoc Buu Nature Reserve, sits between scrub woodland and coastal sand dunes.

"So species that do really well in one habitat or the other will occasionally get together and reproduce to form a hybrid,"Grismer said.

Genetic tests of the new lizard's mitochondrial DNA identified its maternal species asL. guttata. Because this type of DNA is passed down only through females, the paternal species isn't yet known.

(Related:"Evolution in Action: Lizard Moving from Eggs to Live Birth.")

New Reptile May Be in Hot Water

The newly discovered hybrid species may already be at a disadvantage, Grismer added—even though it doesn't seem to be rare in the wild.

For instance, some scientists suggest that hybrid species are more prone to extinction because they don't produce much genetic diversity from generation to generation, according to herpetologist Charles Cole, curator emeritus at theAmerican Museum of Natural Historyin New York.

Genetic diversity keeps a species viable and healthy in the long term.

(See"Hybrid 'Superpredator' Invading California Ponds.")

"At least in terms of lizards, most that are unisexual species—when compared to the lineages of other lizards—have not been around very long,"said Cole, who was not involved with the Grismers' research.

Because the lizards don't combine genes during mating, genetic changes arise by random mutations—which are at least as likely to be detrimental as beneficial.

Lizard Hybrid Hardy as a Mule?

However, Cole cautioned, there are also theories that hybrids can also be healthier in the short term.

For instance, a hybrid's cells may be more genetically diverse than those of nonhybrids, because hybrids carry genes from each of their parent species.

"This might mean that the animals are tougher and more adaptable,"Cole said.

(Read how hybrid panthers are helping the rare cat rebound in Florida.)

For instance, he said, mules—crosses between horses and donkeys—"are sterile, but they are really good robust animals that are in some ways a preferred work animal even though they can't reproduce."

"So what you get in the unisexual lizards is a mule that can clone itself."

forNational Geographic News

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