Two images of a Snowy Egret I managed to capture one morning while shooting at local park with a small lake in East Texas. The Snowy Egrets intentionally hop around on the water to stir up fish and other prey while it is feeding.
Havin owned a Sigma 150 -600 lens, I would strongly advise you to invest in a tripod with a gimbal head, especially if you're considering adding a teleconverter to the mix. Oben makes a good gimbal head (GH-30) that doesn't cost an arm and a leg. Yes, it's a hassle to tote a tripod around, but you'll be amazed in the difference in sharpness and ease of use. After I got one, the amount of 'keepers' I shot went up considerably.