|January 26th, 2013||#1|
Join Date: Nov 2003
Blog Entries: 34
Dung beetle uses the Milky Way to navigate
Dung beetles look to the stars
January 26, 2013
JOHANNESBURG: A species of South African dung beetle has been shown to use the Milky Way to navigate, making it the only known animal that turns to the galactic spray of stars across the night sky for direction.
Researchers have known for several years that the inch-long insects use the sun or moon as fixed points to ensure they keep rolling dung balls in a straight line - the quickest way of getting away from other beetles at the dung heap.
But scientists have puzzled over how the beetles, which perform an orientation dance on top of their dung balls before setting off, achieve a straight line on moonless nights.
To prove the Milky Way theory, scientists at Johannesburg's Wits University took beetles into the university planetarium to see how they fared with a normal night sky, and then one devoid of the Milky Way.
"The dung beetles don't care which direction they're going in. They just need to get away from the bun fight at the poo pile," Wits professor Marcus Byrne said. "But when we turned off the Milky Way, the beetles got lost."
And on cloudy nights without a moon or stars?
"They probably just stay at home," Byrne said. (Reuters)
|January 26th, 2013||#2|
Join Date: Jun 2009
It has been noted that nocturnally migrating birds fare much better on clear nights when the stars are easily visible. An example is the North American Indigo Bunting which flies by the stars as well as using the earth’s magnetic field.
"It appears that they (the Indigo Buntings) learn to recognize the pattern of stars in the night sky when they are still in the nest. For instance, a few years ago, a study found that nestling Indigo Buntings in the northern hemisphere watch as the stars in the night sky wheel around Polaris -- the north star, located above Earth's north pole. Polaris lies due north for those in the northern hemisphere. Being able to identify Polaris in the night sky could help birds find their way north.
To test this hypothesis, the researchers showed the birds a natural sky pattern inside a planetarium. They seemed to fly in a direction consistent with being able to detect the motion of the stars. They knew in their own way which direction was north.
When the experimenters changed the set up so that Betelgeuse was now the pole star which the stars rotated around, the birds flew in a direction consistent with Betelgeuse being the pole star. They no longer went where they should have relative to Polaris. So, they weren't using the locations of specific star patterns. It was just that they were noticing which star the others rotated around. In other words, it wasn't the star patterns, but how they moved that counted.
To further substantiate the claim, it has been recognized that some birds become disoriented on cloudy nights, when they can't see the stars."