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Scientists studying captive breeding of the endangered bamboo-eating bears said on Tuesday pandas are far more likely to mate successfully and produce cubs when they show through a complex series of behaviors a preference for a potential mate.

When giant pandas in captive breeding experiments displayed no such preference, despite being deemed genetically suitable as a pair, their chances of successfully mating dropped to zero.

"Incorporating mate choice into conservation breeding programs could make a huge difference for the success of many endangered species breeding programs, increasing cost-effectiveness and overall success," said conservation biologist Meghan Martin-Wintle of the San Diego Zoo Institute for Conservation Research.

The study involved more than 40 pandas at a conservation and research center in China's Sichuan province. Pandas were put in large open-air enclosures where they could choose between two potential mates.

When both a male and a female showed a preference for each other, there was about an 80 percent chance they would produce a cub. When one of the two showed a preference for the other, there was about a 50 percent chance they would produce a cub.

When neither showed a preference for the other, there was a zero percent chance for a cub.

The pandas showed interest in potential mates through behaviors such as vocalizations called "chirps" and "bleats," and "scent-marking" by rubbing glands against a surface or object. Females showed their angiogenital region to males, put their tails in the air and walked backward toward males. Males performed a handstand against a vertical surface and urinated.

"We learned that, just as in humans, breeding signals are complicated," Martin-Wintle said.

Conservation breeding programs act as a fail-safe against extinction, providing animals for reintroduction to the wild to bolster dwindling populations. Pandas, remaining in the wild in only a few Chinese mountain ranges, have proven tricky to breed in captivity.

"Pairs are selected to maximize maintenance of genetic diversity in the panda population. This is essential for maintaining healthy populations, and currently we have no problem with this," said Ronald Swaisgood, the institute's director of applied animal ecology.

"However, there are often several candidate mates that are genetically suitable, and we believe that behavior and mate choice has a role to play for improving the success rate of breeding among genetically suitable partners."

The research was published in the journal Nature Communications.

(Reporting by Will Dunham; Editing by Peter Cooney)

    The experiment would involve re-purposing the abundant amounts of urine produced at the stadium which Boyer views as a resource that is currently going to waste. Urine is nutrient rich, containing high concentrations of nitrogen as well as phosphorous and potassium.   

    "What you'll see is that you can collect enough nitrogen over those seven home football games to meet the nutrient requirements for that field for the growing season," said Boyer.  

  His idea is to stop streaming urine to a waste water facility and collect the pee in giant vats at the stadium instead to then use to fertilize the field.

    "So you collect urine in the storage tank. Then what you want is for it to sit for a period of time, probably on the order of several weeks. That allows it to change chemistry and it is an important change in chemistry where the nitrogen goes from urea, which is excreted from our metabolism and it gets transformed into ammonia." 

    Ammonia is a powerful fertilizer but according to Boyer, separating the urine from the rest of the waste is easier said than done. 

    It's a problem Boyer and his team are tackling in the urine lab. The team is developing the next generation of waterless urinals and newly designed toilets with the goal of harnessing the pee while using just a fraction of the water needed to operate conventional bathrooms.   

    Once collected in a storage tank and after its chemical transformation, the solution can be further processed to extract the nutrients into a solid fertilizer which can be easily transported. 

    Boyer is confident that his team can figure out the science. He says the biggest problem is getting people over the 'ick' factor. 

    "We know a can should get recycled. I don't think most people feel that way about urine, right? Most people don't urinate and be like that should have been recycled and recovered," he said. "My sort of vision of maybe a slightly skewed world that's what I want people to think about every time they urinate, like wow, those are nutrients that could have been saved and re-used," he added.  

    If all goes as planned, the grass at the Swamp will soon be greener in more ways than one. 

It could only be demonstrated by flying it indoors, due to Singapore's legal requirements for personal aerial vehicles.

Resembling a giant drone, 'Snowstorm' comprises of motors, propellers and landing gears set within a hexagonal frame and can be controlled by the person sitting in it, or remotely.

It's environmentally-friendly too, as the three rechargeable lithium batteries get their energy from solar power. 

Joerg Weigl, who came up with the idea and is one of the supervisors of the project, said he wanted 'Snowstorm' to help people realize their dreams of flying.

"Because flying is now a community. People can now fly with a jetliner, but the feeling of flying got lost on the way. So 'Snowstorm' is our multi-copter where you can get the feeling of flying back, the feeling of flying to anybody who wants to fly," he said.

The team said the current prototype can technically bear the load of a single person up to 70 kilograms for a flight time of about five minutes and for safety, the seat is installed with a five-point harness that secures the pilot to the center of the machine.

However, a dummy, which is a few times lighter than a human being, was visibly easier to control.

Team member, student Wang Yuyao admitted that 'Snowstorm' is still a work in progress.

"The next step is, from an electrical standpoint, it's definitely to have more fail-safes, better stability and easier control for the pilot, and from the mechanical side of the staff, it's definitely more structural stability as well as maybe even more power. We can always add more motors to lift a heavier person," he said.

Rather than a mode of transportation, the team said the flying machine will be more for personal recreational use.

Weigl said he could see it being commercialized some years down the road.

"As soon as you make it stable and possible as a fun activity, a fun activity is what people want and if people want this, it's a product and as soon as it's a product, it's a commercial market (product). That's very simple and it's a commercial market (product) that doesn't pollute the environment, so that is a nice thing," he said.

The personal flying machine was built over a one-year period.

Brain scans on 30 California sea lions detected damage in the hippocampus, a brain structure associated with memory and spatial navigation, in animals naturally exposed to the toxin known as domoic acid, the researchers said.

Domoic acid mimics glutamate, a chemical that transmits nerve impulses in the brain, and leads to over-activation of hippocampus nerve cells and chronic epilepsy, according to Emory University cognitive psychologist Peter Cook, who worked on the study while at the University of California-Santa Cruz.

"The behavioral deficits accompanying brain damage with domoic acid are severe, and may negatively impact foraging and navigation in sea lions, driving strandings and mortality," Cook said.

Hundreds of sea lions annually are found stranded on California beaches with signs of domoic acid poisoning such as disorientation and seizures. Thousands are thought to be exposed to the toxin.

The microscopic algae, called Pseudo-nitzschia, responsible for the toxin occur naturally in coastal waters. Their blooms have become more frequent and severe in recent years. This year's bloom was the largest on record, reaching from Santa Barbara, California to Alaska.

Ocean pollution from chemicals like fertilizers and warming ocean temperatures associated with global climate change are believed to contribute to bloom size and frequency.

The toxin accumulates in shellfish and small fish that consume algae. Sea lions, other marine mammals and seabirds are exposed to it after eating those shellfish and fish.

"Domoic acid-producing blooms have been in the environment for a very long time, but the current pattern of much larger and more frequent blooms causing more visible damage to marine animals has been going on since the 1980s," Cook said.

Sea lions exposed to the toxin had greatly reduced connectivity between the hippocampus and the thalamus, a brain structure associated with sensory perception and regulation of motor functions. Those with hippocampus damage also performed worse on memory tasks such as one involving finding a food reward.

"Hundreds of sea lions end up in stranding facilities each year. A great many of them do die although some can be rehabilitated and survive for some time in the wild," Cook said.

The research was published in the journal Science.

(Reporting by Will Dunham; Editing by Peter Cooney)