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Scientists have announced that the mystery of the “Bermuda Triangle” of the homing pigeon world may have been solved.

For years, scientists have been baffled as to why the usually excellent navigators get lost when released from a particular site in New York State.

But new research suggests the birds are using low frequency sounds to find their way around – and they cannot hear the rumble at this US location.

The study is published in the Journal of Experimental Biology.

The lead author of the paper, Dr. Jonathan Hagstrum, from the US Geological Survey, said that the birds were creating “acoustic maps” of their surroundings.

But some other researchers said the theory was controversial and there was much debate over how homing pigeons navigate so efficiently.

The puzzle of the vanishing pigeons began in the 1960s.

Professor Bill Keeton from Cornell University was trying to understand the birds’ astonishing ability to find their way home from places they have never previously visited.

He released birds throughout New York State, but was surprised to discover that whenever the pigeons were released at Jersey Hill, near Ithaca, they became disorientated and flew about aimlessly.

This happened again and again, apart from on one occasion on August 13, 1969, when the birds’ navigational prowess returned and they flew back to their loft.

Dr. Jonathan Hagstrum has now come up with an explanation.

He said: “The way birds navigate is that they use a compass and they use a map. The compass is usually the position of the Sun or the Earth’s magnetic field, but the map has been unknown for decades.

“I have found they are using sound as their map… and this will tell them where they are relative to their home.”

Scientists have announced that the mystery of the "Bermuda Triangle" of the homing pigeon world may have been solved

Scientists have announced that the mystery of the “Bermuda Triangle” of the homing pigeon world may have been solved

The pigeons, he said, use “infrasound”, which is an extremely low-frequency sound that is below the range of human hearing.

He explained: “The sound originates in the ocean. Waves in the deep ocean are interfering and they create sound in both the atmosphere and the Earth. You can pick this energy up anywhere on Earth, in the centre of a continent even.”

He believes that when the birds are at their unfamiliar release site, they listen for the signature of the infrasound signal from their home – and then use this to find their bearings.

However, infrasound can be affected by changes in the atmosphere.

Dr. Jonathan Hagstrum used temperature and wind records taken from the dates of the various experimental releases to calculate how the sound would have travelled from the pigeons’ base to Jersey Hill.

“The temperature structure and the wind structure of the atmosphere were such in upstate New York that the sound was bent up and over Jersey Hill,” he explained.

This meant the birds could not hear it and got lost – apart from the day that the birds found their way home.

He said: “On 13 August 1969, there was either a wind shear or temperature inversion in the troposphere that bent the sound back down so it arrived right back at Jersey Hill on that day, and that day alone.”

Dr. Jonathan Hagstrum thinks that disruptions of infrasound may also explain other homing pigeon puzzles, where large numbers of pigeons lose their way, such as a race in 1997 across the English channel where 60,000 birds veered off course.

He admitted his work was “controversial”, but said: “This doesn’t prove it by any stretch – but it puts out a new idea, which, as far as I’m concerned, is the best explanation of what pigeons are doing, because it explains what has been going on at Jersey Hill.”

Others have put forward different ideas for how pigeons find their way, suggesting that the birds use smell, visual clues or the Earth’s magnetic field, or even a combination of all of these.

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How zebras evolved their characteristic black-and-white stripes has been a long time subject of debate among scientists.

Now researchers from Hungary and Sweden claim to have solved the mystery.

The stripes, the scientist say, came about to keep away blood-sucking flies.

They report in the Journal of Experimental Biology that this pattern of narrow stripes makes zebras “unattractive” to the flies.

They key to this effect is in how the striped patterns reflect light.

“We started off studying horses with black, brown or white coats,” explained Susanne Akesson from Lund University, a member of the international research team that carried out the study.

“We found that in the black and brown horses, we get horizontally polarized light.” This effect made the dark-coloured horses very attractive to flies.

How zebras evolved their characteristic black-and-white stripes has been a long time subject of debate among scientists

How zebras evolved their characteristic black-and-white stripes has been a long time subject of debate among scientists

It means that the light that bounces off the horse’s dark coat – and travels in waves to the eyes of a hungry fly – moves along a horizontal plane, like a snake slithering along with its body flat to the floor.

Dr. Susanne Akesson and her colleagues found that horseflies, or tabanids, were very attracted by these “flat” waves of light.

“From a white coat, you get unpolarized light [reflected],” she explained. Unpolarized light waves travel along any and every plane, and are much less attractive to flies. As a result, white-coated horses are much less troubled by horseflies than their dark-coloured relatives.

Having discovered the flies’ preference for dark coats, the team then became interested in zebras. They wanted to know what kind of light would bounce off the striped body of a zebra, and how this would affect the biting flies that are a horse’s most irritating enemy.

“We created an experimental set-up where we painted the different patterns onto boards,” said Dr. Susanne Akesson.

She and her colleagues placed a blackboard, a whiteboard, and several boards with stripes of varying widths into one of the fields of a horse farm in rural Hungary.

“We put insect glue on the boards and counted the number of flies that each one attracted,” she explained.

The striped board that was the closest match to the actual pattern of a zebra’s coat attracted by far the fewest flies, “even less than the white boards that were reflecting unpolarized light,” Dr. Susanne Akesson said.

“That was a surprise because, in a striped pattern, you still have these dark areas that are reflecting horizontally polarized light.

“But the narrower (and more zebra-like) the stripes, the less attractive they were to the flies.”

To test horseflies’ reaction to a more realistic 3-D target, the team put four life-size “sticky horse models ” into the field – one brown, one black, one white and one black-and-white striped, like a zebra.

The researchers collected the trapped flies every two days, and found that the zebra-striped horse model attracted the fewest.

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