I had heard it only once before...last summer in the Boise foothills. The habitat on Antelope Island was right for it and the sound I was hearing was distinct. I had my son look it up on iBird and play the sound just to confirm. I was right! It was a Grasshopper Sparrow. Within seconds we found it trilling from the top of a sage brush right on the edge of the road. (Listen to the Grasshopper Sparrow) I'm not sure why the Grasshopper Sparrow song stuck in my memory so profoundly, and I was delightfully surprised that I recognized it.
The Grasshopper Sparrow is not exceedingly common in the intermountain west, so it is a treat when you find its spring and summer haunts. See the Cornell and eBird maps below to get an idea of its range and migration pattern.
There are a dozen subspecies of Grasshopper Sparrow, with four subspecies breeding in North America (AllAboutBirds.org). The most likely in the west, north of Arizona, would be the perpallidus* which, by definition of the classification name, appears "paler" than the other varieties. That description seems to match my photos when compared other photos and illustrations.
I thought the name "Grasshopper" Sparrow referred to the sound it makes, but it turns out that it does eat grasshoppers too!
This was only my second ever sighting of a Grasshopper Sparrow and my first in the state of Utah. Pretty cool!
*Sparrows of the United States and Canada: The Photographic Guide. Beadle & Rising