Great thread with some fantastic information.
I think LionHo nailed my thoughts pretty good with his post. It's uncanny how someone whom I've never met and lives several states away can come to the same conclusions and tactics.
Bobcats aren't hard to call, they are just hard to see. This is why I believe people are much more successful calling bobcats at night. Their big eyes are a dead give away under illumination. During the daylight you don't have this advantage and many called in cats go undetected by even the best trained eyes. One thing, and LionHo touched on it already, is the use of elelctronics. Bobcats are very stealthy and like to stalk into the call in order to get in position for a close kill. If you are using a hand call they are stalking YOU. This means they will use the available cover to conceal themselves from YOU until the last moment. This often means that the first time you see the cat he will either be peering at YOU through dense cover or from around a tree or brush. With electonic, if set up right, you will have a seat to the side of this stalk as it unfolds. With the cats attention and concealment efforts focused on the call he will be much more easily detected.
When possible give him some thin cover to aproach through and he will respond more readily than having to break cover to get to the call.
I can also vouch for the effectiveness of the bobcat in heat sound, as well as keeping the sounds as busy and constant as possible. Here in lies another good reason to use electronics for calling bobcats. Thirty plus minutes of constant calling on a hand call can get you busted and it takes a lot of air. Most of the bobcats I kill will be in the first few minutes of a stand. I feel the reason for this is that I'm usually not calling them from a long distance and it doesn't take long for them to get there. On stands where I've killed bobcats at or around the thirty minute mark, I firmly believe most of those cats had been there much longer but had preaviously been undetected.
When calling in areas with bobcats it is a good idea to get up very slowly when you break a stand. Bobcats typically aren't very spooky and will often hunker down and remain motionless when you get up. When you get up from your stand, pan your eyes around very good. Often times a step or two or the standing position will reveal a cat that had been there all along.
Good Hunting,
Byron