As has been suggested, there are no absolutes. Another factor that SEEMS to determine how likely fish are to chase stuff up high in the water column is how long the fish have been in freshwater. Most of the fish we catch in the late summer have been in freshwater a month or more, although the occasional chromer can be found. As steelhead return to a riverine lifestyle, they seem to act more and more like rainbow trout, and they start eating for the sake of eating. IMO, this is what makes the October caddis such an important bug in fall fishing.

Anyway, we all know that resident rainbow trout can be caught throughout the water column, but dry fly fishing in the winter is challenging at best. If steelhead are rainbow trout, why should they behave much differently?

I do think there is something that separates steelhead behavior from that of resident rainbows: They get increasingly aggressive as they near readiness to spawn. I've seen winter steelhead caught in March and April on skaters (big, bright things that look nothing like food). I also had a huge one roll on my strike indicator once while doing some dirty a$$ nymphing. I think this is evidence that when steelhead near spawning time, they get ornery and will strike at stuff just because it's invading their space. I think that might have something to do with why flies with big profiles are productive for spring steelhead.

So you see, the answer is....?