Since we are in such geographically diverse regions, some of our experiences will probably be quite different. For instance several of this group recently have remarked about how the absence or presence of crows seems to be an indicator. If you are in snow covered territories where coyotes may be highly likely to show during daytime, I can see where that could very well make a difference as a confidence builder for the coyotes. But where I'm located, coyotes almost never show until darkness sets in. Crows have long since gone to roost here before coyotes would arrive, so I shoot every crow that hits the bait to keep them from wiping me out. I'm generally using smaller chunks of deer, table scraps, and dry dog food mixed with grease or gravy of some sort in order to avoid attracting buzzards that would also wipe out the bait constantly.
I keep a light shining on my bait all night. The light is on the back shelter of my shop and is located about 60 yds from the bait. I shoot from the house which makes it 145 yds to the bait pile for a shot. I have three trail cams and 2 alert sensors located at the bait pile on 2x4 poles. The coyotes will occasionally be spooked by the IR lights on the cameras when they come on if the coyote happens to be looking at it as turns on. They can see the IR source (led's) light up, but I don't believe they see the IR light itself. Sometimes I think it is actually the click which some cameras make that causes them to look at the IR lighting coming on. Usually however they pay no attention at all to the IR lights and I've never observed them being spooked by the spot light from the shop.
Also I haven't observed any reaction to the sensors, but I keep a piece of tape over the little red led light.
The first year I killed 14 in 4 months from Sept. to Dec. with this setup. Then I went a long time until March before I saw any and finally killed two more. The next year I killed 5 and was surrounded by soybeans during summer and fall until late Oct. The first year I was surrounded by corn. This year 2013, corn surrounded me again. I've managed to kill 5 off the bait again, but had a couple of mess ups and didn't get shots at two other which I should have gotten but never showed for another opportunity. However, I called and killed 4 at night from my yard during that time. Maybe they would have eventually made it to the bait pile, but they just haven't seemed to be as interested in bait this year. We do have a lot rabbits around this year, and maybe that has given them plenty of food without needing to hit the bait here.
I'm just trying to explain what I've experienced both good and bad. I have a friend who believes the coyotes get to where they smell death when so many have killed in one place and it takes a long time to wash away that scent. I do know that most of us experience an initial flurry of activity and then it falls way off. Maybe that is just a result of shooting most of the easy ones out of an area.