I’ve been practicing photographing birds in flight using my Sigma 150-500mm lens without a tripod. It’s a heavy lens but almost impossible to photograph flying birds using a tripod. It’s a fairly heavy lens but it’s getting easier and easier to hand hold it. Geese are a good subject for inflight shots. They’re big, not as fast as some other birds, and we have a lot of them.
Maralee
Through My Lens 
You might want to give a try resting it on the crook of the elbow of the opposing arm. I occasionally take my left arm, rest my hand on the right shoulder, raise my elbow, and rest the long lens on the bend of the elbow as I look through the viewfinder.
It gives a pretty stable platform and is pretty good for panning and following objects because you move your whole torso to do so. The only downside is that you can’t work the zoom when you do that, but with long lenses, that’s a difficult thing to do anyway.
Great suggestion. I’ll give it a try. Thanks.
your learning to pan. Hard to do & one never does become excellent at it!
Think of it like a bike wheel.Your at the centre & your subject is at the rim. You can do one of three things.Too fast,too slow or perfect! It’s like there is a spoke joining you both!.Hold your breath, tuck your elbows in.Obviously only use the only centre focus point & AI servo because of it’ll be moving quickly.
Thanks. Its something I will keep practicing.
Well done, Maralee. I have the same problem with my new Sigma 150-600. But I will try and try and try! Do you also use a monopod?
I’ve tried using a monopod but have found handheld works better for me – even though the lens is heavy.
Thank you! I have to find out what works better for me.
Love the warm light on these geese.
You may want to give a Gimbal head a try or a Gimbal head light like the Wimberley Sidekick. I really like mine, and my keeper rate went up by half when I started using it.