Fish adjust their expectations everyday.
Paul,
Maybe all the time...
I think that all of us anglers that have fished awhile carry around somewhere buried in our heads a reference book of all our experiences a stream...The hard part sometimes is being able to listen to these experiences when they are trying to remind us of similar situations...It can be like a sixth sense or, as you alluded to, lock us in to something that's flat out wrong and waste our time.
Hatch matching is usually where I start but I agree with Gonzo that selectivity can be rare and maybe even not a good strategy for a fish and opportunism is more likely where they live.
I was watching a Cedar Waxwing and a Baltimore Oriole last night snacking on the berries from my Amelanchier. I was wondering aloud to my wife about why they don't seem in the mood to save something for later. Instead they took every berry that was ripe period...They have competition and aren't guaranteed anything will still be there once they return...So they get it while they can because there may not be "a later".
The Browns on the Au Sable are a wild surly lot and are not fond of daylight or straying to far from good feeding spots. They are basically lazy. A good way to fish this river is to "work the wood" as Rusty Gates used to say. We run our fly of choice right up against structure where the Big Boys like to lay and wait for food to come to them.
So, they are lying there feeling safe and feed on anything that gets pushed up against the wood they are hiding under...They seldom move and if you are a couple inches out on a pass with your fly you might as well be a mile. These fish are used to many different things getting stuck up against the wood or that may be making an attempt to crawl up and away from the water...They see a variety all the time. They can afford, most of the time, to forget about selectivity...They are in the best spot after all.
A few days prior to the one I discribed above I fished an olive stone down the river and placed it right along the wood as close as I could get it (If your fly isn't getting snagged from time-to-time, you are not close enough)and with the best drift I could muster. It was a floating version of what we call the "Mattress Thrasher" (this is usually to cover the Yellow-Throated Stone but mine matched the little olive). I moved fish all day.
Rusty had a fly called "The Not" (or the Knot) which was a parachute fly along the lines of a Borcher's that he thought was a fair imitation of a spinner. He thought that fish tucked up against the structure see spinners in one form or another all day and you could basically fish this fly to great success depending on your casting skills all the time. I have heard it called "Head-Hunting" but I prefer to call it "Trying to Raise the Dead". :)
The fly I was using (I'll give page numbers tomorrow so folks can look at it) was as follows: Three fibers of pheasant tail tied a little longer than normal length, abdomen dubbed rabbit with fine gold wire rib, thorax dubbed yellowish rabbit, In front of thorax wrap a couple wraps of brown rooster hackle (this is the twist to a softhackle I mentioned in the first post), then a couple wraps of partridge...The rooster helps keep the Pat from collapsing and a bit more flaired out.
If I really thought about this fly, and I have :), it could be a fair imitation of the Hendrickson spinner (they were still around the first part of my trip), the March Brown itself or it's spinner...So, as a match-the-hatcher I wasn't too far off except I couldn't get a trout to tell me exactly which hatch I was matching...:)
Spence
The old time guides have a saying on the Au Sable, "When in doubt, tie on a Borcher's!" If you were to tie the parachute version on, you are probably in the ballpark at least and would be hard pressed to do better IMHO.