ALWAYS IN SEASON: Robins are common but mysterious at same time

Swamp sparrows. Marbled godwits. Yellow-rumped warblers. Ruby-crowned kinglets. Sandhill cranes. LeConte's sparrows. Turkey vultures.

This is a short list of the birds reported in Grand Forks this week.

Yet, I have been fixated on American robins, perhaps the most familiar species of all birds in our area, and certainly one of the most abundant.

Perhaps this is because the robin is convenient, and I've been traveling.

Robins occur almost everywhere in North America, except the high Arctic.

Nor are robins especially fussy about habitat.

In our area, robins show up in city parks, backyards, farmyards and shelterbelts. Almost every spot has its robin. Or two. Or more.

Robins are gregarious birds. Spot one. Spot another. That's pretty much the rule with robins.

Robins are hardly so exclusive as that, however. They occur in quite large flocks sometimes.

Ralph Kingsbury, the Herald's economics columnist, pointed this out to me earlier this year. He'd seen a big bunch of robins and was surprised by their number. I told him I thought big bunches of robins were unusual. But I've realized that was misleading. In fact, robins occur in quite large flocks.

Once, hiking in the North Unit of Theodore Roosevelt National Park in western North Dakota, I came upon a big group of robins drinking from the Little Missouri River. It was early winter, and they'd converged on an area that offered open water.

On Christmas bird counts at Devils Lake and Edinburg, N.D., I've encountered flocks of robins.

So, they are hardly solitary birds.

But I hadn't considered how these groups of birds interact until last week, when a flock of 20 or so robins settled into the space between our house west of Gilby, N.D., and the county road that passes it. The robins behaved like guests at a human dinner party, moving from group to group, sometimes exhibiting aggressive behavior, but soon settling down, apparently eager to avoid giving offense.

It's wrong to ascribe human characteristics to wild creatures, of course. Nature's creatures have their own society with its own norms.

As it happens, robin society is not very well understood.

It's easy to see the interactions between robins, of course. Robins are so common that they can hardly be overlooked.

Familiarity doesn't suggest understanding, however, at least in the case of robins.

Here's what Don and Lillian Stokes, authors of "A Guide to Bird Behavior," have to say about the American robins: "There are some important mysteries surrounding its life."

One of these is its courtship activity. There doesn't appear to be any.

Courtship rituals are often obvious among birds. These range from mutual preening to elaborate displays.

None of these has been documented for American robins. However abundant, however easy to observe, robins haven't been caught courting.

Robins are unique for another reason. Their behavior varies seasonally.

We're all familiar with the predatory activity of robins in summer. They move methodically across lawns and parklands in search of worms.

In other seasons, however, robins are fructivores -- a fancy word for fruit-eater. They often settle into ornamental crabapple or mountain ash trees, for example.

Increased planting of fruit-bearing trees -- especially those that hold their fruit throughout the winter -- has helped American robins survive Northern winters. Robins are hardly common in Grand Forks in midwinter, but it's not unusual to spot one on a winter walk.

Still, this species remains one of the most reliable signs spring has arrived.

Whatever the weather, robins show up in our area in big numbers in mid-March. This suggests that they are more responsive to light than to weather conditions.

By early April, most years, robins are abundant here -- but whether these are the robins that will stay and raise young here is uncertain. It may be that early arrivers are bound farther north. Or perhaps not. We simply don't know.

We do know, however, that robins are quite faithful to the territory where they were born. Extensive research has shown that most robins return to areas quite close to the place where they were fledged.

Yet, there's no way of knowing whether the robins at the dinner party on my lawn are bound to stay or bound to go.

Mike Jacobs is publisher of the Herald.