Snow began falling during the night, and by the time I woke up this morning everything in the backyard had changed. The little rock that juts up in the middle of the blackberry patch was missing, as was the top edge of the old well cover, and a couple of big boulders that probably were deposited here by the last glacier were hidden under mounds of white fluff.

It has been snowing all morning, and I have been sitting by the big window with a cup of tea, watching to see how our neighborhood critters cope with the storm. Four squirrels are busily scampering around in the trees, and they seem particularly frisky this morning, chasing one another in a spiral up the trunk of the pine tree, out onto limbs, and showing off by leaping across places where they don’t usually leap. Years ago, squirrels had not yet tried to cross from the oak tree to the red maple because the branches were at least 15 feet apart, but one day we noticed a squirrel running up to the end of a branch on the oak tree and looking across. He hesitated, and then scampered back a few feet. He did this several times before launching himself into the air, landing successfully on a slender maple branch. After that, other squirrels crossed there, and over the years it has become a regular part of their route. Now, those trees have grown so much that their branches almost touch, and even very young squirrels make the crossing confidently.

As I watched, a squirrel raced down the trunk of the big pine tree, stepped gingerly onto the snow and then bounced across it, sinking in with each step and leaving little squirrel-size dents in the white surface. When he poked into a hole in the snow all I could see was the top of his head and the tip of his bushy gray tail, but then he vanished, reappearing with something in his mouth that looked like an acorn. He bounced back to the tree with his treasure, scooted up to a branch, and sat there to eat. Another squirrel saw he had food and chased him up the tree trunk, but he escaped out onto another limb to enjoy his meal in peace.

It’s snowing more heavily now, and each breeze blows a curtain of snow swirling down off the roof and past the window. The birds are so hungry I have had to fill the bird feeder twice this morning. I have decided goldfinches are not polite. They crowd onto the tube feeder, and if they can’t get a perch they lean down and snap at those who have one. Chickadees watch from the maple tree, and whenever one of the goldfinches gives up his perch they quickly fly in, grab a seed, and leave with it.

Being snowbound for a day offers a welcome change of pace, and an excuse to pay more attention to what goes on just outside the windows. It’s also good practice for the Great Backyard Bird Count, which is coming up the weekend of Feb. 18 to 21. The basic idea of the GBBC is simple: watch your bird feeders, or take a short walk in the neighborhood. For each species of bird seen, keep track of the highest number of individuals observed at any one time, and at the end of the day submit a report over the Internet at www.birdsource.org. There is no cost, and anyone can participate. The website has full instructions and a short video explaining the event. During that weekend, species distribution maps will be updated frequently, so anyone with Internet access can watch them change as reports are received. The results will provide a valuable snapshot of winter bird populations across North America, and will become part of a larger database used by scientists around the world. I plan to report the birds I see, even though I may only see a mob of goldfinches and a couple of chickadees. Too bad they don’t let us count squirrels.