Trillions of high-flying migratory insects cross over UK

The BBC London news reported this at the end of December 2016…Unseen and unnoticed by humans, researchers found that 3.5 trillion bugs and butterflies annually migrate across the region. The findings were published in the journal Science.

The researchers say their mass is equivalent to 20,000 flying reindeer! Really?

The count was made using vertical radar and insect nets mounted on balloons.

Over a 10-year period, the scientists looked at insects flying night and day, between 150 and 1200m above the ground.

While their origins weren’t recorded the researchers believe that many were travelling to and from the UK from across the English Channel and the North Sea.

Although the vast majority of the insects were tiny creatures like cereal crop aphids, flies and midges, there were also larger ones including hoverflies, ladybeetles, moths and butterflies.

93094705_insects3

Photo : Graham Shepard

One of the most surprising findings was that while the smaller insects took off regardless of wind direction, all the medium and larger creatures showed a really clear pattern of seasonal movements.

“The insects are basically measuring the wind direction and deciding whether or not to fly on that particular day or night,” said Dr Jason Chapman, from the University of Exeter, the paper’s co-author.

“It signifies that the insects have a compass mechanism in order to know which is north and south, but they also have the capability to then fly up high into the sky and assess the direction of the wind and relate it to the compass direction and make a decision on whether to fly or not – that’s a quite complex set of things and many, many species are doing this.”

The researchers found strong migrations northward in the Spring with subsequent movements south in the Autumn.

The scale of these movements essentially cancelled each other out over the period of the study.

93094702_insects1

Photo: Ian Woiwood

What was also somewhat surprising were the distances covered and the speed of travel. The researchers found some insects were able to travel at 36-58 kilometres per hour, over distances of 200-300km.

The ability to study these creatures over long periods of time may be very helpful in determining the changes to the environment.

“Animal migration, especially in insects, is a very complex behaviour which takes millions of years to evolve and is very sensitive to climatic conditions,” said Dr Ka S Lim, from Rothamsted Research, another author of the paper.

93094791_insects5

Photo: Ian Woiwood

“Global climatic change could cause decline of many species, but equally other highly adaptable species thrive and become agricultural crop pests.”

The researchers say that they have been able to estimate the mass of the creatures flying over the southern part of the UK at around 3,200 tonnes of biomass, which according to the authors is the equivalent of 20,000 flying reindeer.

“It’s also nearly eight times the mass of the number of migratory songbirds that are coming out of the UK every year,” said Dr Chapman,

“But yes, 20,000 reindeer is the correct figure, it’s a calculation I did when I realised the date the paper was coming out!”

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s