Pan-tilt heads are commonly found on inexpensive tripods. When locked down they will hold a camera with up to a medium telephoto lens. I have used this particular head/tripod combination extensively with the Canon 100-400mm as well as with shorter lenses. I found it necessary to lock the tilt function each time I took my hand away from the rig to keep the lens from tilting forward and crashing against the tripod legs. The constant locking and unlocking was time consuming particularly during intense photo sessions with a wildlife subject. As I have said before any tripod is better than no tripod and if this is the only head you can affort so be it. It will do the job as long as it and the legs are sufficient to support your camera and lens.
A good ball head is a step up from the pan-tilt as its ball can be adjusted to securely hold a medium telephoto while still allowing panning and tilting. Some of the larger top of the line models will also handle large telephotos.
A notch in the side of the head allows the ball to easily be flipped into the vertical position or any angle in between. These heads are no doubt the gold standard for use with the shorter lenses and very good with medium telephotos.
Gimbal Head, Kirk King Cobra
For handling the large telephotos the gimbal heads are unmatched. Gimbal heads support the lens at their balance point. Setup with the locks loose the lens can be panned and tilted effortlessly and is ready to fire without tightening any locks.
The largest drawback I have experienced with the King Cobra is range of motion with the 600mm lens.
Interference between the pan knob and the lens barrel greatly limits pointing down however I cannot attribute this limitation to any missed shots in the field.
And with the smaller barrel of the 100-400 lens it does not impede the range of motion.
Wimberley WH-200 Gimbal
Another popular gimbal head, possibly the most popular, is the Wimberley WH-200. Like the Kirk it also balances the lens for effortless movement and does not require any tightening or loosening to go from shooting to pan-tilt.
Unlike the Kirk their is no issue with range of motion with the Wimberley WH-200 regardless of the the size of telephoto lens.
Gimbals heads require the use of rotating lens collars ruling out using these heads with short lenses however nothing else matches them when it comes to handling the long glass. With their smooth effortless panning and tilting following moving subjects is a breeze. In short if the big glass is your game a gimbal should be supporting it. Adding a good ball head to your bag will allow you to swap heads and handle any outdoor photographic situation you might find yourself in.