I did go by the cattle egret rookery last evening to get a closer look. There are two large trees with easily over 50 birds nesting. I think the egrets are tolerating the grackles because the baby birds have not hatched out. I saw several of the birds bringing in twigs still.
Leaves from the trees are building up on the ground, along with quite a lot of bird poop. I am sure the apartment building residents are not happy as the trees are right over the front entry to their building and their parking spaces. The smell is already pretty strong--I can imagine what it will be like in a month or two.
That being said, it is exciting to see an active rookery up close. I am not sure the attraction of a busy area of town to establish one, but I don't pretend to know what birds are thinking.