As we struggle through the two hardest months of winter-January and February-it is hard to contain our impatience with the season. Lengthening daylight and somewhat less-frigid temperatures tell us that spring is coming, yet it is still so far away – or is it?

Some people have reported seeing robins in different areas of the state. Traditionally, robins are thought of as harbingers of spring, and each year many people wonder if seeing robins in winter is unusual. Does their presence really mean what we think it ought to mean? The answer is: yes and no, depending upon where you live.

If you live in most areas of Canada, Alaska, and the northernmost tips of the U.S., then yes, the appearance of robins is truly a sign of spring. Robins living there fully vacate their breeding ranges for the winter. They may return quite soon; an early record of a robin’s spring song is dated March 12, 1977, in Alberta, Canada.

Which brings me to the other side of the question: one reason robins are able to return to their breeding grounds so early in the season is because they don’t migrate very far south to begin with. In Maine, as in the rest of the contiguous states, robins seen during winter may be those who’ve migrated from slightly further north or even birds that stay in the area year-round. So, no – the sight of robins will not necessarily be a sign of spring (unless you are eternally optimistic).

Staying on or near their breeding territory gives the birds an edge. This, of course, depends upon the availability of food, which also depends upon the severity of the season.

In spring and summer, the sight of robins foraging for earthworms on countless lawns across the United States is common. It is hard to miss the birds then; they seem to be everywhere! Obviously, frozen ground and snow cover precludes this, so the birds switch to a diet of winter fruit. This may include the fruit produced by hollies, mulberries, cedar, juniper, or crabapple trees.

This winter fruit crop is highly variable and transient. Instead of scattering into small groups as they do in the warm months, robins now must mass into larger flocks and wander over greater distances. This increases their chances of finding such ephemeral food sources, making them comparatively less conspicuous -they are no longer stationary (relatively speaking!) lawn ornaments.

It’s conceivable that your neighborhood robins may be even just a few miles away, having found an abundant winter fruit crop, and you’d never know it. However, the birds may fully vacate the region during severe winters with poor fruit crops.

The question of robins in winter and their “harbingers of spring” status is a complex one, involving many conditions and variables. Let’s just say that once we hear that first spring song – that sweet “cheerily, cheer-up” – we’ll know it’s truly spring.

Interested in documenting the winter movements of American robins and other birds? The Cornell Lab of Ornithology and National Audubon’s “Great Backyard Bird Count” is coming up, Feb. 18-21. For more information, visit: www.birdsource.org/gbbc.

NEWS bird columnist Chris Corio can be reached at bdnsports@bangordailynews.net