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Nest boxes aid in bluebird survival

Now that we are finally shedding this cloak of winter, waterfowl, raptors and a few songbirds are starting to show up. It's an exciting time for us residents of the northern plains, with thoughts of summer activities already playing around in our heads. Never call us anything if not optimistic.

Of the few avian species that have made a showing so far, perhaps none is more surprising to some than the Eastern bluebird (Sialia sialia). Sure the folks with boxes lining their rural fence line are awar, but the majority of us may not know that it's one of the first migrants to show up in the spring. The first day of March marked the first report I am aware of this year in the state. That was over a month ago. I checked the weather in Fargo - we had a low of five degrees that day.

What is curious is this species is known to feed extensively on bugs and other invertebrates, making them a welcome sight in rural areas. So what kinds of bugs were out at five degrees? Well, none. So what in the world do these birds do for food when they show up that early in the season?

The answer is fairly straightforward in that it merely changes its diet to accommodate more fruit and vegetable matter. Several other species are known to make such a switch as well, including the familiar American robin, another early migrant. I would consider this ability to adapt to dietary conditions a very advantageous evolutionary trait. Think of the birds that can eat almost anything and you come up with some pretty successful populations - house sparrow, American crow, rock pigeon, etc.

But Eastern bluebird numbers are sort of limited. Why? Because their ability to change their diet cannot overcome their hardwired instinct to nest in cavities. And that is where the trouble lies. In earlier times it was easy, with limited competition from other species. Enter the house sparrow and the European starling. Both are introduced, non-native species which also nest in cavities. Competition for nest holes can be fierce. And, given the fact that both invaders are permanent residents, they get dibs on available sites from the get-go.

Bluebirds, fortunately for them, are pretty. I've mentioned anthropomorphism before but just to refresh, it is the bestowing of human qualities on non-human or non-living things. That is precisely what is happening here. We favor bluebirds because they are attractive to us. It's just human nature. To illustrate, how many gray catbird or grasshopper sparrow clubs are there? You get the point. Unless you are a bird which exhibits a certain colorful flair or desirable trait, you are for the most part on your own.

But bluebird populations are holding up with help from organizations such as the North American Bluebird Society. This 30-year-old group was set up to promote the welfare of bluebirds mainly by the placing of artificial nest boxes. It appears to be largely successful, as more and more seem to be placed along fence rows.

There are two other bluebird species to be aware of, but only one with any real chance of showing up here. Besides our eastern bluebird, there is a Western and a mountain bluebird. Mountain bluebirds actually nest across a large part of western North Dakota and are remotely possible around here (there was one spotted in Clay County last spring). Forget about seeing a Western bluebird here, I don't think North Dakota even has a record. You'd have to head to western Montana before you could be confident at all in seeing one.

Eastern bluebirds are unmistakable. Males are a bright blue all over the back, tail and head, with a red-orange breast. Females are duller in color with more gray or gray-brown instead of blue. Mountain bluebird males look the same on the back but its front is a striking powder blue, giving it a two-tone look.

The Eastern bluebird's nesting range is basically the entire eastern U.S. and southern Canada but peters out at about the Montana border. Its favored habitat is any open ground with limited undergrowth. Large parks, orchards, pastureland, even open suburban areas are likely places to find them. They are here already, so start looking. Just don't expect to see them feed on insects just yet.