Orono, MN, USA
This tiny bird is full of amazing traits. With no gullet, they can only eat one seed at a time, and with a very high metabolism they need to eat almost constantly which could present a problem for them when they sleep, or when temperatures drop. They’re able to lower their metabolism when they sleep, and to help keep them warm they start growing thicker feathers in the autumn which can increase their body weight by as much as 25%. Those feathers act as a warm blanket, trapping warm air between their body and the difference between the outside air and their warm feather buffer can be as much as 100 degrees. They store food all summer long, and in order to remember where they stashed it, their hippocampus, the part of the brain that regulates memory increases in size allowing them to find their hidden seeds, then it shrinks again in the spring when fresh food is readily available. Amazing little birds, indeed!