If you feed birds then you know what a scene is going on just outside your windows. All the birds that have been visiting your feeders sporadically are now left with no choice of a place to find food. The drifting snow has covered all food that they had access to and now they are counting on your ice-free and food-filled feeders and scattered seed to make it through this stressful and lean time. Most birds will still have some stored fat reserves that they are likely burning through, and access to food is critical during and especially after fierce winter storms.
Birds have developed and evolved many special adaptations to survive brutal winter conditions. It is a good thing they are not as frail as they appear, or there would be no birds able to survive winters harshest conditions. For instance on cold winter nights, Black-capped Chickadees reduce their body temperature from their normal temperature of 108 °Fahrenheit by as much as 22 °Fahrenheit to conserve energy. This ability is called torpor and is either rare in birds, or at least is poorly understood and as yet little studied.
A birds’ greatest asset is its feathers. Feathers have evolved into many forms and are a wonder of engineering. They are strong, lightweight, and durable, as well as having insulating capabilities far superior to fur or any man-made material.
Birds have the ability to contour and move their feathers using muscles under their feather tracts. They can flatten or fluff-up their feathers, allowing them to create more airspace between them. This allows them a way to regulate temperature. The hotter they are, the flatter the feathers with no airspace; conversely, the colder they are, the fluffier they are as they puff up and trap air that acts as additional insulation between their feathers, their bodies and more feathers. Today you should see lots of fat and fluffy looking birds as they are attempting to stay warm during the cold spell.
This is an excerpt of the Weekly Bird Report. The full essay is posted below as audio - give it a listen.