This winter, a strange natural phenomenon will be visible in car parks of various supermarkets like Tesco, Asda, Morrisons and Sainsbury's and inspiring a 'treasure hunt'.

No, it won't be shoppers buying Christmas chocolates in October (though actually that will probably also happen - they're already on offer).

According to wildlife experts, British supermarketcar parks will become a hotspot for a famous winter visitor this year. According to the Lancashire Wildlife Trust, supermarket car parks have become a key site for 'irruptions'. This is when migratory birds known as waxwings fly to the UK for its milder winter compared to their native Scandinavia. And these waxwings' favourite foods include rowan berries, which are usually found in supermarket car parks, the trust says.

Because these irruptions are irregular and hard to predict, wildlife experts say they spark a 'treasure hunt' of people looking to spot them.

It reports: "These stunning birds live in Scandinavia and eastern Europe for most of the year, but if their berry crop is poor, they'll fly to the UK in huge numbers called 'irruptions'. We normally get a couple of hundred birds, but when the berry crop back home is particularly bad we can see tens of thousands flooding trees around the UK.

"Waxwings' favourite berries grow on rowan trees, which are commonly planted in supermarket car parks."

It adds: "Waxwings are sociable, resilient birds of the passerine order. They do not breed in the UK but grace us with a visit over winter.

"They arrive in huge flocks and can turn up anywhere - from town centres and domestic gardens, to local parks and supermarket carparks.

"These flocks are called 'irruptions', a name befitting of their sudden appearance in droves. For some of our followers and keen birders, waxwings' nomadic wandering and irregular irruptions are somewhat of a phenomenon, inspiring a treasure hunt to spot them before they disappear.

"Happily, they are classified as 'green conservation' status. The seeds of fascination for these birds are also sown by the fact that waxwings are simply stunning. With a tropical mix of graceful greys, browns and apricots with pops of sunshine yellow and red, they are a distinctive, exotic sight."