Sparrows, finding shelter in the storm. On this bitter cold Friday in the Meeteetse area, the temps have stayed around -17 below all day and with wind and snow added to the mix, I wondered about the birds. Mybirdbuddy.com says, "....feathers are fantastic heat traps...down...covers the majority of a bird’s body in a thick layer underneath the longer exterior feathers.....birds can “puff these up”, a process known as ptiloerection, which gives the appearance of being fatter, when in fact they have just pushed them out and spread the finer filaments across each other, meshing in that heat that escapes from the inner body....This fluffy barrier traps pockets of air close to the body which are then heated by the radiated warmth from within the bird, remarkably retaining up to 90% of their core heat.."