Spring brings familiar faces

When we first bought this place, we dealt mostly with the Mrs. She had some tips and suggestions about things in general (although not nearly enough as it turns out) but stumbled on the killdeer.
After we moved in, I noticed that a pair of robins were building a nest on the ledge outside the master bedroom window. When I mentioned this to the Mrs. on a day she had dropped by to pick up some mail, she lit up and said that the robins build a next there EVERY YEAR. She mentioned that there were these birds... and here was the stumble - she didn't know the word in English for what she was trying to describe. These birds that ran up and down the road every year. In my mind, she was talking about the ROAD, the country road that runs in front of our house. I couldn't imagine what she was thinking, so I offered up 'pigeon' and she agreed that was it. Every year the pigeons run up and down the road.
Not so. Every year a pair of KILLDEER (or what I think to be killdeer because according to the 2 books about bird identification that I've been given, there are many types of pipers and other similar birds that might be expected in our region and they all look similar) run up and down our DRIVEWAY. Last year I hated to mow the lawn, for fear that I might run over their nest. By the end of the summer, the adults (with their scrawny 4 offspring) seemed to be hunkered down mostly in the ditch. But this year, there are three adults, and they are keeping pretty close to the parking area. It's still too early to be mowing the lawn (and so to educate them about danger), so I'm a bit worried that they might nest somewhere we don't notice, somewhere in the way of the riding tractor.
Right now they seem to be mostly hanging out near the 'lake' that encompasses 1/5 of one side of our front lawn (a result of the winter thaw and the gravelling that we did in November which has dammed up the water from running over the driveway). They seem to also like the deep grooves the bobcat (and later the snow plow) have made in that part of the yard. It seems like good eating and drinking in that area for a killdeer. But they blend in so well to our winter-killed brown grass that it is hard to see if they've nested or not.
I suppose that it is a matter of watching out for them (or the absence of one, which might indicate a hidden nest) and perhaps leaving off the mowing in that area (which would suit me fine) until the red clover takes over. I'm planning on over-seeding the clover in a week or two, which might eliminate the need for mowing all together - the clover made a huge indent into the grassy lawn last year.
I'm pretty enthralled by the visits from last years' friends, or from the decendents of those parents of last year. I wake up every morning and pull the curtains back, hoping to see the beginnings of a robins' nest on the ledge. How do they know to return and carry on, year after year? But it's a complete bonus to have these signifiers of the approach of spring - the killdeers running, the robins nesting, the other wildlife emerging after a long deep winter. It may likely snow again before May, but at least we know here that spring is settling in.