When you go to Big Beef Creek to see the Great Blue Heron’s react to Bald Eagles trying to steal their catch and the few eagles there seem content to catch their own fish, you have to turn to the far less dramatic arguments that take place between the herons themselves.
Great Blue Herons seem to pay close attention to how successful other Great Blue Herons are. Invariably, if one heron is successful in landing several fish, other herons will come over to try their luck. Sometimes they try to drive the original heron away and claim the fishing spot.
I still haven’t figured out why one heron will retreat while another will stand its ground, forcing the charging heron to divert its charge. You might think that chunking down five fish that weigh almost as much as you do would encourage you to leave when another bird attacks, but that’s not always the case. I’ve seen a heron protect its spot for four or five hours without bothering to catch another fish.
This heron looked like it was ready for a fight as it landed in the middle of three or four herons who were steadily catching fish.
Most of the herons totally ignored the bird, and he ignored them, but it picked out one of the herons and leapt toward it,
causing that heron to leave rapidly.
Not sure how GBH display dominance, but judging from my short sample the heron who can jump the highest seems to have a definite advantage.