The wren gets friendlier as the weather gets colder – and they huddle for warmth like penguins do

The birds, which store very little body fat and lose heat easily, huddle together for warmth and protection rather like penguins, their heads inwards. The greatest number found to be doing so is 61, counted in a Norfolk nesting box in the winter of 1969. The host male will reasonably expect to mate with one or more of his female guests when spring arrives.

Wrens eat insects, spiders and tadpoles – but they also like a bit of grated cheese

With winter food scarce, wrens may forage under the snow for their natural diet of insects and spiders, their small size allowing them into areas that other birds can’t penetrate, an ability that applies throughout the year as they can reach cavities denied to larger beaks.