A gimbal head for your tripod is an essential tool for capturing fast-moving birds in flight with a heavy camera and long lens.
Birds in flight move at tremendous speeds. Small songbirds like wrens and sparrows fly 10 to 20 miles (16 to 32 kilometers) per hour, while ducks, geese, and pigeons can fly at speeds up to 60 miles (97 kilometers) per hour. Some birds, like the peregrine falcon and golden eagle, have been timed diving at speeds exceeding 170 miles (274 kilometers) per hour. 
Now, instead of fighting your equipment, you’ll find that a gimbal head moves weightlessly and without friction – in a word, effortlessly.
I have no experience with a gimbal head other than the Wimberley. Others may be perfectly satisfactory. But its hard to imagine any gimbal head moving smoother than the Wimberley. It certainly took my game to a new level. I remember thinking the first time I used it that it gave me the best of both worlds – the stability of a tripod and the freedom of shooting handheld. It’s not quite like shooting handheld because you can’t point straight up, but it’s pretty close.