Herons and Egrets can be quite loud and I have heard Cormorants making screeching noises at times but thank goodness it's not constant because there are lots of cormorants around here. When we were walking around the lake the other evening, there were lots of cormorants roosting in the trees and some were really loud ... I don't know if it was their way of conversing with each other or if the screeching was a territorial thing, with each one vying for the tree branches.
I see large flocks of White Ibis together feeding or perched side by side without issues but when I see a single Egret and another happens by, there tends to be a bit of a scuffle with one usually chasing the other off. This morning the Snowy Egret and Tricolored Heron were perched on the power line together and then feeding near each other along the waters edge but another white egret came flying in and chased the other egret off ... and boy was there a loud commotion during the scuffle. I've also seen Egrets chasing each other in flight and making a loud ruckus when doing so.
I typed a post and uploaded a few photos but had two windows opened and went to close out of one and shut down ATP by mistake so let me try this again. 
