IN the previous post, a mention was made about Chickadee eating a bird. This behavior is not unusual for this species of the chickadee family of which all of them do act like carnivores but its from a frozen carcass not a kill. It's because of their tremendous heat loss from winter's grip for their little sizes, they pursue anything to regain the heat rich fat reserves from protein laden food sources. Overnight is a tough time for this species especially when its very cold and frigid..Read more about them from a link I found ( click on it)
http://chippewa.com/dunnconnect/sports/outdoors/chickadee-survivalist-extraordinaire/article_863fa76c-4fc5-11e2-a26d-001a4bcf887a.html