Are Towhee Calls Irregular?

I did a good deal of work in the yard yesterday, giving me a chance to at least enjoy the backdrop of bird calls and songs. As would be expected I was "serenaded" by the hisses and calls of upset Chickadees, Titmice and Wrens, all still fairly territorial even this late in the season. But I also noticed a fair amount of calling from Rufous Sided Towhees. A male made a great show in my southwest feeder area, proclaiming himself with a vigourous "Tow-hee!" while foraging for food below the feeders and underneath bushes and brush piles. It amused me that this fellow had no problem calling attention to himself. Clearly he was confident that he could dash for safety when necessary. While the Towhees are certainly perennials here, it seems to be that I only hear them now and then. Is my memory faulty? or are they limited edition musicians? I really must pay more attention...