(Science Times)

Birds of Paradise Glow on Mating Parade

Elaborate poses, tufts of feathers, flamboyant shuffles along an immaculate forest floor -- male birds of paradise have many ways to woo a potential mate.

But now, by examining prepared specimens at the American Museum of Natural History in New York, scientists have discovered what could be yet another tool in the kit of the tropical birds -- a visual effect known as photoluminescence.

Sometimes called biofluorescence in living things, this phenomenon occurs when an object absorbs high-energy wavelengths of light and reemits them as lower energy wavelengths.

Biofluorescence has already been found in various species of fishes, amphibians and even mammals, from bats to wombats.

Interestingly, birds remain woefully understudied when it comes to the optical extras. Until now, no one had looked for the glowing property in birds of paradise, which are native to Australia, Indonesia and New Guinea and are famous for their elaborate mating displays.

In a study published in the journal Royal Society Open Science, researchers examined prepared specimens housed at the American Museum of Natural History and found evidence of biofluorescence in 37 of 45 birds-of-paradise species.

"What they're doing is taking this UV color, which they can't see, and reemitting it at a wavelength that is actually visible to their eyes," said Rene Martin, lead author of the study and a biologist at the University of Nebraska-Lincoln. "In their case, it's kind of a bright green and green-yellow color."

In short, biofluorescence supercharges a bright color to make it even brighter.

Of all the birds-of-paradise species, three genera (Lycocorax, Manucodia and Phonygammus) showed no evidence of biofluorescence.

Martin said this could be because those birds tended to be much more monogamous, which would mean that there's less need for elaborate displays and competition between males. -- JASON BITTEL

Boat Crew Spots Thousands of Dolphins in a California Bay 'Superpod'

On a small inflatable boat on a Friday last month, Evan Brodsky and two co-workers with a whale-watching tour company were on the lookout for gray whales on the Pacific blue waters of Monterey Bay, along the central coast of California.

After four hours of searching, the team had spotted only one whale.

But instead of heading back to the harbor, as the team usually would, Brodsky, a boat captain and videographer with the tour company Monterey Bay Whale Watch, said he had an "itch" that there was something they could not yet see and decided to stay out on the water.

First, the team of three spotted about 15 dolphins swimming together. It followed the small pod, knowing that dolphins are highly social marine animals that usually travel in larger groups.

Some 30 minutes later, 15 dolphins had turned into hundreds. Then there were thousands.

"I kind of just take a glance and scan the horizon, and maybe about a mile and a half from us the water literally looked like it was boiling," Brodsky, 35, said. "It was foaming. There were so many dolphins there."

In previous outings, Brodsky had seen pods of hundreds, sometimes thousands, of dolphins, but this was the first time that he had seen a gathering of so many northern right whale dolphins, mixed in with Pacific white-sided dolphins. In the past, he had seen only a few hundred of the species in one place.

Using his drone and past experience on the water, Brodsky estimated that there were more than 2,000 dolphins in the pod his team saw that Friday. "The whole time we were just saying: 'Oh my gosh, oh my gosh, this is so amazing, I can't believe this,'" he recalled. While the team is on the water almost every day, Brodsky said that the sight of the dolphins still gave him "butterflies." -- SARA RUBERG and CHRISTINA MORALES

Hummingbirds Living in a Hive Found for the First Time

Hummingbirds are tiny and delicate, but don't be fooled: They are among the most aggressive birds in the avian kingdom. Their territorial fury is especially aimed at other hummingbirds. Competition over a patch of flowers or a mate often results in high-speed aerial chases, divebombing and beak jousting.

So when Gustavo Cañas-Valle, an ornithologist and birding guide, stumbled across a cave full of hummingbirds nesting and roosting together in Ecuador's High Andes, he could hardly believe it.

"I thought, 'This looks like a colony,'" Cañas-Valle said. He added, "They were like bees."

He documented 23 adult birds and four chicks, all of the subspecies Oreotrochilus chimborazo chimborazo, commonly known as the Chimborazo hillstar.

Cañas-Valle's discovery, described in November in the journal Ornithology, may be the first documented example of hummingbirds that nested and roosted communally. It is also notable that he found the birds engaging in both these behaviors in the same space -- something that even highly social species from other bird families tend not to do.

Juan Luis Bouzat, an evolutionary geneticist at Bowling Green State University in Ohio and another author of the study who is also Cañas-Valle's former graduate adviser, said the finding raised fascinating questions about the role environmental factors could play in driving group living and in promoting the evolution of certain social traits.

Bouzat and Cañas-Valle at first hypothesized that harsh environmental conditions along the Chimborazo volcano where they found the nests had forced the birds together. The birds live more than 12,000 feet above sea level on a sparsely vegetated slope where it is hard to come by nectar-providing flowers, water or shelter from freezing temperatures and biting winds.

"Either you aggregate or perish," Bouzat said.

But this may not be the full story. Cañas-Valle explored the region and found six other examples of hummingbirds nesting and roosting together. -- RACHEL NUWER

This article originally appeared in The New York Times.