That looks like a great color. I contacted Wapsi since it's not easy to find. Their reply:
"The Wood Duck color is still available in 70 and 140 denier sizes. It is a fairly new color, brought out just a few years ago so many dealers may not have brought it into their stores. "
Being relatively new in a sea of thread options, it seems possible that shops may not even have it on their radar. I will be letting one supplier know of my interest in this color.
In one particular image I saw of UTC Wood Duck, it appeared reasonably close to Danville olive 6/0. Perhaps with a slight golden-tan tone, though, which I do like. Do any of you see a likeness of Wood Duck to another thread on the market?