That would be tough to do, Doug -- but not impossible. (maybe expensive, though.) First, you'd need to get instrument readings to identify the frequencies of the traffic, then build in a filter for those freqs. Either that, or add a frequency generator for those wavelengths to cancel them out like they can do for tinnitus. The question would be whether the gobbles or other turkey sounds fall within that range. I don't think that stuff is built in to any units currently available. I do know, however that you can tune a Walker's Game Ear to be more sensitive to higher or lower freqs. That might help some.
Goog luck! Hope that helps.