Insects migrate in wind highways

Migrating insects use highways in the sky to speed their journey.

Researchers say moths and butterflies use sophisticated methods to find winds that will take them in certain directions for thousands of kilometres.

The little creatures travel on winds of up to 100km (60 miles) per hour.

They use internal compasses to find these fast moving winds to carry them to their journey's end.

Sky highway

It may seem a little difficult, in the depths of winter, to imagine sitting outside on a balmy summer's evening gazing up at the velvety night.

But, if you can, cast your mind's eye back because above you was a windy highway used by thousands of these delicate migrating creatures.

And the same journeys are sometimes carried on over several generations of insect.

The scientists say that each insect uses the same complex methods to whisk them to their wintering water-holes in the Mediterranean and back to more northerly climes in the summer.

"We were surprised by the scale of the movements, although we wouldn't have started the research without some idea of what was happening," says Dr Jason Chapman of the Rothamsted Research Institute in Hertfordshire, UK, who is the lead author of the report.

"What is also surprising is that very few of the insects end up going the wrong way".

But most moths and butterflies look like they can hardly make it across the garden. So how to they avoid getting ripped to shreds in these fast moving winds?

"When you are flying within the windstream you don't feel it" says Dr Chapman. "Having said that, we think the way they choose the winds that are fastest is through some sort of turbulence mechanism.

"As the data has built up over the years we have been amazed by the subtlety and sophistication of the system."

It is still not known exactly how this mechanism works - that will be for further study.

The group that published the research is one of only three is the world using special radar that can detect insect movement up to a kilometre in the air.

And, while the research is fascinating in itself, it has useful applications. "One of the people working on this research has also been working on data about the midges that carry bluetongue", says Dr Chapman.

"Hopefully other scientists' prediction models of the future, for some of the moths that could become invasive pests in this country, will incorporate our research".

Arctic tern's epic journey mapped

The Arctic tern's extraordinary pole-to-pole migration has been detailed by an international team of scientists.

The researchers fitted the birds with tiny tracking devices to see precisely which routes the animals took on their 70,000km (43,000 miles) round trip.

The study reveals they fly down either the African or Brazilian coasts but then return in an "S"-shaped path up the middle of the Atlantic Ocean.

The long-distance adventure is described in the US journal PNAS.

"From ringing, we knew where the Arctic tern travelled," said Carsten Egevang of the Greenland Institute of Natural Resources.

After setting out (yellow line) the birds pause in the North Atlantic (red circle) to feed. Going home (orange line), they follow the winds Total distance travelled 70,900km On southbound leg: 34,600km Daily progress south: 330km On northbound leg: 25,700km Daily progress north: 520km Within Winter grounds: 10,900km

"The new thing is that we've now been able to track the bird during a full year of migration, all the way from the breeding grounds to the wintering grounds and back again."

The avian world is known for its great migrations.

Albatrosses, godwits, and sooty shearwaters all undertake epic journeys. But none can quite match the Arctic tern's colossal trip.

Starting in August and September, this small bird - which weighs little more than 100g (3.5oz) - will head away from Greenland with the intention of getting to the Weddell Sea, on the shores of Antarctica.

It will spend about four or five months in the deep south before heading back to the far north, arriving home in May or June.

A team from Greenland, Denmark, the US, the UK and Iceland attached small (1.4g/0.05oz) "geolocators" to the animals to find out exactly where they went on this polar round trip.

The devices record light intensity. This gives an estimate of the local day length, and the times of sunrise and sunset; and from this information it is possible to work out a geographical position of the birds.

The geolocators were provided by the British Antarctic Survey (BAS).

"The use of these devices on seabirds is not only revolutionising our understanding of migration patterns, but the resulting data on distribution also help address the requirement to identify important biological hotspots," said Richard Phillips from BAS, a co-author of the PNAS paper.

With such a small bird, the trackers also need to be tiny

The first surprise is that the terns do not make straight for the Antarctic when they leave the Arctic, but make a lengthy stop-over in the middle of the North Atlantic, about 1,000km (620 miles) north of the Azores.

Here, they feed on zooplankton and fish to fuel themselves for the long journey ahead.

"We were able to compare biological productivity in the ocean from satellite imagery and we could see a high productive area that the birds will spend time in," said Mr Egevang.

"Even more importantly, it's the last high productive area before they enter tropical waters where we know productivity is low."

THE LONG DISTANCE FLIER Scientific name: Sterna paradisaea Average wingspan of 75-85cm Breeds in Arctic and sub-Arctic Lays eggs in small ground scrape Feeds on fish and crustaceans Birds live more than 30 years

The birds then head south along the coast of western Europe and western Africa before making a choice, either to continue hugging Africa or sweep across the Atlantic from the Cape Verde Islands to continue the journey along the Brazilian coast.

About half the birds that were tracked decided to take the South American path. It is not clear why, but the researchers believe wind might make either route seem favourable to the terns.

After spending their northern winter months in Antarctic waters, the terns then fly back towards the Arctic.

But rather than retracing their southward flight paths, the birds follow a gigantic "S" pattern up the middle of the Atlantic Ocean.

"This is completely new knowledge," Mr Egevang told BBC News.

"They make a detour of several thousand km but once we start comparing the route to the prevailing wind system, it makes perfect sense - moving in a counter-clockwise direction in the Southern Hemisphere, and clockwise in the Northern Hemisphere.

"It's just more energy-efficient for them to do that even though they are travelling several thousand more km than if they flew in a straight line."

Fire breaks out on passenger train in south-west London

A fire has broken out on a passenger train in south-west London, leading to the evacuation of 300 passengers.

The fire broke out in a power unit on the South West Trains service in Berrylands, Surbiton, at 1030 GMT.

It took firefighters an hour to bring the fire under control. No-one was hurt in the incident.

Rail services from Guildford and Basingstoke into Waterloo have been suspended and services out of Waterloo have been disrupted.

A London Fire Brigade spokeswoman said: "A small fire broke out in a power unit under the train carriage."

It caused a "small amount" of damage to one of the carriages and two fire crews attended the incident.

She added: "Passengers were evacuated as a precautionary measure and there were no reported injuries."

'Walked on tracks'

A Network Rail spokesman said: "Passengers have been taken off the train safely by emergency services.

"There have been no injuries but there will be some disruption."

One passenger onboard the train said he had been delayed for two hours on his journey from Weybridge to Waterloo.

The 30-year-old, who did not want to be named, said some commuters got off the train and walked down the tracks to nearby stations.

He said: "Some people decided to brave the cold to get to other stations.

"Ironically, the meeting I was due to attend in London had actually been cancelled."