The pilots of a grounded solar-powered airplane say they put too much stress on the batteries of their aircraft as they were leaving Japan for a five-day record-breaking flight to Hawaii.

The pilots then discovered they had too much insulation around the batteries for them to adequately cool down during the flight through tropical skies.

Rampant illegal trading in ivory in Hong Kong is pushing elephants towards extinction, conservationists said Thursday, reporting more ivory items on sale there than in any other city.

The sale of ivory items from government-registered stockpiles predating the 1990 ban is allowed for domestic use in Hong Kong, but the report finds tusks from recently slaughtered elephants are being passed off as old ivory on a huge scale.

A Thai farmer was arrested Thursday after he confessed to erecting an electrified fence which killed three elephants close to a national park, police said.

The three pachyderms -- one male and two females -- were found dead on Wednesday near a village pond outside Kaeng Krachan national park in Prachuap Khiri Khan province.

The only surviving giant panda twins ever born in the U.S. are celebrating their second birthday.

Zoo Atlanta officials said Mei Lun and Mei Huan turned 2 on Wednesday and were given special treats in their habitats. They say the pair will be treated to ice cakes during a second celebration Saturday.

The sun-powered plane Solar Impulse 2 will be grounded for months in Hawaii to carry out battery repairs, after completing nearly half of an unprecedented round-the-world flight, the project said Wednesday. 

"Irreversible damage to certain parts of the batteries will require repairs which will take several months," it said in a statement.

Populations of some of Australia's iconic birds -- including the laughing kookaburra, magpie and willie wagtail -- are in decline in parts of the country, according to a report released Wednesday, with habitat loss, feral cats and foxes among the likely threats.

The State of Australia's Birds report, published by Birdlife Australia, was compiled using data from 420,000 surveys collected by volunteers across the continent since 1998. 

Thousands of rare forest turtles have been rescued from horrifying conditions of captivity in the Philippines, saving the critically endangered animals from possible extinction, wildlife experts said Wednesday.

More than 4,000 live freshwater turtles and 90 dead ones were found in a pond inside a remote warehouse on the western island of Palawan four weeks ago in one of the country's biggest wildlife rescues, they said.

A simple camera adjustment has helped scientists illuminate the usually undetectable spots on black leopards -- a trick they say will help them tell individual animals apart and aid the animals' conservation. 

Scientists studying leopards on the Malay Peninsula, where most of the big cats are jet black, had difficulty telling the animals apart, an obstacle which was hindering research.

An unmanned NASA spacecraft whizzed by Pluto, beaming to scientists a message that it survived its historic encounter before sending back the closest look ever of the distant dwarf planet.

After a three-billion-mile (4.8-billion-kilometer) journey that took nearly 10 years, the nuclear-powered New Horizons -- about the size of a baby grand piano -- snapped pictures of Pluto as it hurtled by on auto-pilot.

An unmanned NASA spacecraft whizzed by Pluto on Tuesday, making its closest approach in the climax of a decade-long journey to explore the dwarf planet for the first time, the U.S. space agency said.

"The New Horizons spacecraft passes its closest approach mark at Pluto after a three billion mile journey," a NASA commentator said as spectators waved flags in a crowded room at the Johns Hopkins Applied Physics Center outside the U.S. capital, Washington.