The puffin has been revealed as one of the master builders of the bird world.
Research in Shetland by a team from the Institute for Oceanography in Kiel, Germany, has found burrows dug by the seabird cut temperature swings to a fraction of what is experienced outside, turning a daily range of 34C into less than 4C.
According to Ulrike Kubetzki this creates the stable conditions needed by newborn puffins in their first week out of the egg, regardless of the extremes of weather, as well as protecting them from predators.
The experts found tremendous variation in size, depth and angle to the wind, with some burrows dug into grassland and crevices and others simply adapting empty rabbit burrows.