Well, here I am sitting at my computer; outside the weather has turned wintry – 2 inches of snow have fallen and meteorologists report temperatures will dip into the teens tonight. And just a few days before it had been so warm and spring-like!

I was reminded once again how unpredictable Maine weather is, especially in March. But I am heartened by the promise of moderating temperatures predicted for the middle of the week, and by the sight of little birds that bring bits of sunshine with them as the days begin to lengthen.

These aptly named American goldfinches have two plumages; during the winter the males are a dull olive-brown. In fact, at this time they are hardly recognizable as the birds we know during the spring and summer. It is then that they undergo an amazing transformation: they turn a dazzling yellow all over, an effect that is further highlighted by inky black caps and black wings.

Most of our colorful songbirds, such as the wood warblers, arrive here already resplendent in their breeding plumage. But because goldfinches frequently over-winter in this area, their feather change is observable over a period of time – and it seems to keep pace exactly with the advancing season.

Several weeks ago a flock of goldfinches visited my thistle feeder almost every day. I studied them carefully, hoping to see the telltale spots of yellow. But there was only the slightest hint of it – just the palest wash of gold, slight enough to make me think I was only imagining things. I realized this was the same attitude I had toward the approach of spring. Was I only imagining the snow starting to melt and the weather starting to warm?

Just last week, when the weather was the warmest it had been, the finches visited my yard again. This time, the changes were unmistakable: they looked as if someone had flicked a wet paintbrush at them. Some of them had splashes of yellow on their backs; some had little yellow buttons near the tips of their folded wings; others looked like they wore yellow scarves. There was no doubt they were changing, as was the climate.

Soon they will be ablaze in all their glory, as will the springtime. I can just see it now: the soft blue of a warm spring sky, the bright green of newly unfurled leaves and shoots of grass, and – flitting through it all – these little feathered vessels of sunshine, sweet harbingers of summer.

Chris Corio, a volunteer at Fields Pond Nature Center in Holden, can be reached at fieldspond@juno.com