A pair of flickers has dug a nest hole in a big sugar maple in the backyard of a house at the end of our alley.

The tree was damaged in a storm two years ago. The storm snapped one of the main vertical limbs at a point about 20 feet from the ground. Apparently that part of the tree was already dead and therefore weakened. The owner had the downed section hauled away, but he didn’t touch the ragged stub of dead-wood that remained attached to the rest of the maple. That ragged stub is just the sort of thing that flickers would find attractive.

I had been hearing the male singing his loud maniacal laughing call for some weeks, but I didn’t see him until just a few days ago. He was spending a lot of time at the top of a light pole a few doors from us, and at first I thought the nest might be in a small cavity at the top of the pole.

But then I realized that he was using the pole as a song perch and as a stopping place on his way to the nest. He would land on the pole, his mouth full of some kind of insects, and wait there for a few minutes before flying to the maple.

When I looked at the maple; I couldn’t find the nest at first, but when I walked around to the front of the house and looked over the roof, I could see the neat round hole. The female was inside looking out.

Flickers are woodpeckers, and like other woodpeckers they nest in holes in trees. They will take over natural cavities, but they prefer to dig their own. They are strong enough to dig into live wood, but they prefer the easier excavating that comes with dead wood, especially dead wood that has been softened a bit by rot.

Woodpeckers are very important animals. The nest cavities they dig, use, and then abandon will be next year’s nests for everything from the great crested flycatcher to the common goldeneye–a species of duck–to the flying squirrel.

Flickers are the largest woodpeckers nesting in Cook County and the third largest in North America. The pileated is bigger, but its nearest nesting sites are in Michigan and Wisconsin. The ivory-billed is even bigger than the pileated, but it has sought sanctuary in Cuba and probably no longer breeds on mainland North America.

Flickers are built like linebackers, with thick necks and broad, sloping shoulders. They are slightly longer than the typical robin and much more robust.

Flickers have long, straight, stout beaks, gray crowns, a flash of red at the nape of the neck, and tan cheeks and throat set off by a black bib. Their breasts are white speckled with black and their backs are brown heavily barred with black.

The males show a black stripe extending back from the beak, and both sexes have a prominent white rump that shows plainly in any bird flying away from you.

Flickers range over the whole of North America from the tree line in the north to Nicaragua in the south. They are partially migratory. The northern birds go south for the winter, the southern birds stay put.

Our local birds are somewhat in between. Some of them go south; some of them stay here. We also get large numbers of migrant flickers passing through in spring and fall. They are among the early migrants in spring, arriving here in numbers as early as the middle of March.

If you spend any time at all in one of the lakefront parks in September or October, you will almost certainly see a flicker. Migrants are a constant presence in those months, and the prominent white rump makes them easy to identify with the naked eye.

North American flickers used to be split into three separate species. The yellow-shafted flicker was the eastern form. It was named for the golden yellow color of the underside of its wing feathers. You can see this color on a bird flying overhead, and with the sun above shining through the wings, the effect is extraordinary.

The western form was the red-shafted flicker, named because the undersides of its wing feathers are red. The third form was the gilded flicker, which lives in the deserts of the southwest and builds its nests in the trunks of saguaro cacti.

The three were lumped because investigations showed that they all interbred freely wherever their ranges overlapped. It is possible that the amount of interbreeding has increased because of the settlement of the Great Plains. The vast treeless areas of the shortgrass prairie would once have been a considerable barrier to tree-dwelling species. The eastern and western populations could have met each other only in the river valleys where some trees grow. The planting of trees in towns and farmsteads opened new areas to flickers and probably increased the amount of contact between eastern and western forms.

The newly lumped flickers were officially renamed the northern flicker by the American Ornithologists Union. The AOU’s committees hate to leave a bird unmodified, but they seem to have an equal dislike for adjectives that are excessively colorful or descriptive. “Northern” is one of their favorites. “Common” is another.

As a conspicuous bird that frequently lives near humans, the flicker has acquired over 100 different unofficial common names. My own favorite is the yellowhammer, a reference to the flicker’s habit of drumming on anything resonant–hollow logs, drainpipes, tin roofs–to proclaim its territory. Alabama formally identifies its state bird as the yellowhammer.

Flickers are not birds of the deep, dense woods. They like more open areas with rather widely scattered trees. In presettlement Illinois, they would have favored the savannas rather than the river-bottom forests.

Their liking for open areas with only a few trees has made it easy for them to adapt to the changes we have wreaked on the landscape in the past few centuries. Cemeteries are open areas with scattered trees, and so are city parks, farmsteads, suburbs, and all but the most densely populated urban neighborhoods.

So it is not surprising that flickers are living at the end of our alley. I know that a pair nested successfully–they raised four young–along the river in Horner Park last year, and that is only a few blocks from here. I’m sure they nest in most of our larger parks and cemeteries.

Like most hole-nesting birds, they have a rather long nesting cycle. Their eggs hatch within two weeks of laying, but the young are born naked and helpless and it is another four weeks before they are ready to leave the nest. In contrast, robins, whose young do not have the protection of a nesting hole, complete the whole cycle from egg laying to nest abandonment in three to four weeks.

Flickers sometimes feed in standard woodpecker fashion, hitching themselves up a tree trunk, searching the bark for bugs, but they can live happily in parks and neighborhoods because much of the time they feed on the ground. Ants of various kinds are their favorite food, accounting for about a half of the diet of the average flicker. They also eat various other insects and an assortment of wild fruit.

They are quite noticeable when feeding on a lawn. Ground-feeding birds, such as robins, hop and run with heads and breasts held erect. But a flicker feeds on the ground with a body that evolved for feeding on vertical tree trunks. On the ground, it can raise its head up to look around, but it usually holds its body more or less horizontal, parallel to the surface, a woodpecker turned 90 degrees from its usual feeding position.

The flickers in our alley have one big worry right now: starlings. Starlings are also hole nesters, and they can’t dig their own holes. They take over woodpeckers’ holes and they don’t wait until the woodpeckers are through with them. One-on-one, a flicker would almost certainly prevail over a starling, but starlings don’t operate one-on-one. Every time I go by the house with the maple, I see four or five starlings sitting in the tree. They are awaiting an opportunity. If those flickers ever leave the nest unattended, the starlings will toss out the young, and that hole will be a starling nest.

Meanwhile, I am checking the plans I got from the Illinois Department of Conservation for building a flicker nesting box. The box looks a lot like your standard birdhouse. The main difference is that after you build it, you stuff it with sawdust. Starlings won’t remove that sawdust, but flickers will dig it out just as they would dig out the inside of a rotting tree trunk. Maybe next year, I can get the flickers to nest in my yard.