Why is the Humber a 'service station' for birds?

A unique combination of factors makes an area of the Humber Estuary "like a motorway service station" for migrating birds, wildlife experts have said.

The waterways and beaches around Grimsby and Cleethorpes see thousands of birds arrive each autumn as they make their way to Africa from the Artic.

Parts of the Humber Estuary were designated as a Site of Special Scientific Interest in 1988 and are protected by law.

Abi Sheridan, ecology officer at North East Lincolnshire Council, said: "We've got mud flats and the salt marshes, lots of food resources, we've got lots of places for them to rest and recuperate on their journey."

Birds which can be spotted in the region at the moment include black-tailed godwits, geese and ducks, and Ms Sheridan's favourite birds, the curlew, which she described as "quite elegant looking " with a "distinctive call".

The advice the ecologist has for people wishing to see wildlife at this time of year is to head to Cleethorpes beach at low tide and use a "good pair of binoculars" or a camera with a strong zoom function.

Why do geese fly in a 'V' formation?

While no one knows exactly why geese fly in formation, there are two reasons why this it helps them, according to the RSPB.

The first is the formation, with the front goose flying lower and the ones at the back flying higher, helps them to conserve energy while flying long distances..

The shape also helps the birds to check on each other while flying and avoid mid-air collisions.

Why do migrating birds fly at night?

Ms Sheridan said you can often hear geese flying over at night at this time of year, and called the "honking" noise they make "quite spooky".

During the day, the air above the earth is affected by thermals caused by the sun heating up the ground or sea.

Many birds use thermals to support their flying habits, for example, hunting for food. Thermals can slow down geese, which are flying many thousands of miles.

The cooler, more stable air of the night skies makes it easier for them to fly and less susceptible to predators.

How do birds know it's time to migrate?

Ms Sheridan said: "The simple answer is up north it's cold and there's not enough food for them.

"That combination causes them to release hormones tells their brains that it's time to go."

However, when birds might decide to make the journey, and how long it will take, is not an exact science.

She said: "It's quite variable in terms of when they arrive. In autumn, we can get quite strong winds which can affect their journey times."

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