What is there to talk about in January when we are having record setting cold? The weather of course! The polar vortex has come for a visit, making life more complicated for us. If you are like me you also wonder (and worry) about the animals out there. How do they survive through this bitter weather? Most just hunker down, finding shelter where ever they can, trying to be out of the wind. Food sources are what keep most going, burning lots of calories just to stay alive. Some will not make it, but that is the course of nature through the lives of most species. They, in turn, provide sustenance for others.
While watching birds at my feeders (a perfect activity for cold weather) I was struck by how these tiny feathered creatures can thrive at thirty below. Why are they not just frozen lumps? They don't even huddle for warmth! So I went looking for answers...
First of all, their feet. Not a feather in sight! They stand on the snow, perch on cold metal. How do they do that? It turns out that they have a network of arteries called the rete mirabile (meaning wonderful net), that flows through their tiny bodies. The blood cools as it travels away from their hearts, not even trying to maintain heat in their feet. As it flows back to the heart, it is warmed again so that when it reaches the heart it is warm. Their arteries actually sink further into their bodies in the winter, providing extra protection from the cold. So why don't their feet just fall off? Because their lower feet and legs are designed to have almost no blood flow to them. They just don't need the blood to do much for the feet, so it doesn't matter if they are cold. Some species, such as water fowl, while sit with their feet tucked up under them. As long as well meaning humans don't make them move too much, they can maintain their warmth, even on ice.
One species, that comes here for the winter from the north, uses their metabolism to stay alive Pine Siskins can increase their metabolism up to 40% higher than other birds their size. When in extreme cold (down to -70) they can accelerate up to 5x normal for several hours. Now that takes a lot of calories to burn. So how do they find that much food in the dead of winter? They have managed for centuries to survive. They feed on pine seeds, available in the deepest snows. But they will come to feeders and eat also.
So now we come to feeding the birds. There are studies out there that show people feeding birds can be beneficial for them. It can increase their survival rates and promote better breeding in the spring. Other studies show that it can increase disease by bringing together many birds to one spot that would never normally be close to each other.
Like most things in the world, you need to weigh your options. Keep your feeders clean. Watch for signs of disease and clean more often if anything appears. Spread out your feeders so there is less crowding. Feed high quality food. I think that seeing the birds outside my windows on cold winter days is beneficial to my health and mental well being. Hopefully it helps them too. From the flocks that come, they seem to appreciate it!
Pileated Woodpecker, one of the bigger birds that stop by...
