Mower spares field sparrow nest by inches

Much to my chagrin, I've already mowed the yard three times this spring. There are so many things I'd rather do, but grass grows so quickly this time of year that I've got to keep it manageable. But even while mowing, I sometimes make fascinating discoveries.
While mowing a narrow strip of grass that borders the gravel road by the house, a brown blur caught my eye just in front of the mower. I suspected that I had flushed a sparrow, but I didn't see it well enough to identify. It seemed to appear out of nowhere, so I wondered if it had flushed from a nest.
Native sparrows often place their first nest of the year on the ground. There's really little choice if they hope to hide it from predators. Woody vegetation is still leafing out, so the best cover is on the ground under tufts of dead grass entwined with new growth. In one published account describing 173 May field sparrow nests, 135 were on the ground. In July, none of 240 nests were on the ground.
I've encountered these early ground nests quite often with field sparrows, song sparrows and towhees. An early nest, even on the ground, is the best way to avoid a variety of snakes that devour eggs and chicks. If these birds can get a brood out of the nest before snakes get too active, the nesting season is guaranteed to be successful.
Bird spotted
After some thought, I convinced myself that I had indeed flushed a nesting bird. I waited a few hours, then returned to the general area and again flushed the bird. This time I got a good look at a field sparrow.
I was hardly surprised because a male field sparrow has been defending a territory around the house since early April. Its rusty crown, pale orange bill and wing bars made identification easy. The male's song, a series of whistles that accelerates into a trill much like a pingpong ball bouncing on a table, is also distinctive.
I searched the area where the bird flushed but couldn't find a nest. I didn't want to be too aggressive for fear of inadvertently stepping on and crushing the eggs. Then I recalled another interesting habit of ground nesting species. When alarmed by a predator or intruder, they often slip off the nest, run quietly several feet away and then fly off.
Predators search the area where they saw the bird and quickly lose interest when no nest is found. It's similar to the deception practiced by killdeer when it lures predators away from a nest with its familiar broken-wing act.
But I'm no dim-witted predator. I assembled my pack (my wife and daughter), explained the situation and had them join the hunt. We again approached the general area quickly and quietly. I told them to note exactly where they first saw the bird. A quick approach might not give the bird time to slip off the nest.
Nest found
The plan worked perfectly. The bird flushed from a dense tuft of dead grass when we got about 4 feet away. From directly above we could see nothing. But when I parted the tallest stems, there it was -- a tightly woven cup with an inside diameter of a bit more than two inches. Lined with fine grasses and rootlets, it cradled four pale-green eggs with fine rusty spots marking the large end.
The female will incubate the eggs for 11 or 12 days. The young leave the nest at about 10 days old. Sometimes the male tends the young while the female starts a second nest. Two broods are typical, but three are possible.
Turns out I missed the nest with the mower by about six inches. So don't get too carried away when tidying up the edges of the lawn. An unsightly clump of dead grass might be just that; or it might shelter the nest of an early ground-nesting bird. It wouldn't hurt to examine these clumps before blasting through with the mower.
Send questions and comments to Dr. Scott Shalaway, RD 5, Cameron, W.Va. 26033 or via e-mail to sshalaway@aol.com.