In this unusually cold and snowy winter, you probably find yourself gazing out the window and wondering how the birds and other animals make it out there. I mean, just look at those tiny naked legs and feet standing in the snow, or on the ice! You just want to order them some little boots, don’t you? And those ducks floating blithely about in ice water like they signed up for some some masochistic, never-ending polar plunge. How do these little critters manage what we could never do?
The answer is, they’re built different. From their feathers to fat to feet to food, our birds are designed for just such a winter. Let’s jump feet first into this topic. Bird feet have a special heat exchange system, thanks to the close arrangement of the arteries and veins, that warms the cold foot blood before it heads back into the body, thus cooling the warm blood going into the foot, reducing heat loss. Plus their feet are mostly just bone, skin, and sinew, with few nerves, so they don’t feel much, hence their ability to stand barefoot on the ice all day like some extreme performance artist.
Feathers are of course key to their winter success – these marvels of natural engineering are almost weightless yet extremely tough and weatherproof - take that, Gore-Tex. Layers of down and contour feathers combine to form an almost impervious surface to water and heat loss, and birds can add insulation in the form of air layers by fluffing up the feathers – you’ve probably seen birds in your yard in winter proportioned more like a tennis ball than a sleek, aerodynamic flying machine – when it comes to winter fashion, sometimes you just have to sacrifice form for function.
Birds have to survive all the cold and snow while maintaining a much higher body temp than us - up to 108 degrees F in chickadees. This takes a lot of food, plus a parlor trick known as “regulated hypothermia”, wherein they can drop their body temperature as much as 22 degrees at night, something my wife’s feet are also able to do. Chickadees, nuthatches, jays, and even woodpeckers will stash food in fall and winter to get through the lean times. Chickadees apparently grow their hippocampus by 30% in fall to help them remember where they left all this food.
The birds that amaze me are the ones that refuse to visit feeders, especially Brown Creepers and Golden-crowned Kinglets, two of my all-time favorite species. These tiny birds (technically speaking they are teeny-tiny) survive as far north as Canada all winter on a strict diet of insects that they somehow find by constantly probing around on bark and conifer needles. I’ve never seen either species even give side-eye to my feeders, preferring to tough it out the old fashioned way. I don’t know about you, but I’m not exactly swatting away insects on sub-zero February days, so how they manage this is beyond me.
With so much frozen, including harbors, marshes, and salt bays, water birds know how to find the open water pockets created by groundwater seeps and outflows. I’ve been watching a small frozen saltmarsh in Orleans all winter, where some weeks almost the entire marsh is frozen. As the deep freeze wore on, I went from seeing four to finally just one Great Blue Heron huddled by the same small seeps and open water patches the ducks were crowding into, and had assumed the others either left or died, but was surprised to see all four this week. The small sections of creek that stay open in this tiny marsh are apparently full of fish, as they are supporting about 20 fish-eating birds in the form of mergansers and herons – on Monday I watched a Red-breasted Merganser pull out a small, wriggling American Eel.
This marsh is also where I heard my first singing Red-winged Blackbirds, a few optimistic males belting out their hopeful song on a sub 20 degree morning. It gave me great hope that soon we wouldn’t have to stare at the frozen snow feeling bad for the birds, for spring is just several long, cold, then muddy months away!
