A while ago I had a theory that mornings were best spent birdwatching inland, and afternoons at the waterside, because water birds were less likely to make themselves scarces later in the day. I put this to the test as best I can in Wiltshire, and 16 sessions later I find I was wrong: the water birds behave pretty much as predicted, but at least round Corsham Lake a good deal of what you see is not on the water, but in the surrounding area, and that stuff is lots more visible in the morning. I've put more details on http://www.mcdowella.demon.co.uk/MorningEvening.html if anybody is interested.