re: Question for OT Ornithologist. Black birds and White birds on the LSU lakes.

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Its hard to tell, they look similiar in size. I am usually out there at dawn or before.

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I'd imagine the black birds are cormorants and the white birds are various egrets.

Roosting with like birds more than likely. If you were a black bird sleeping in a group for "protection" from predators, would you want to sleep next to the bright white bird?


Edit to add:

Now, as to why the cormorants (assuming that's what they are and we aren't talking about darker egrets (herons) here) have the top while the egrets are below them, or which stratus is better, I'm unsure. Sleeping in trees over water is usually predator avoidance of mammalian predators.

Perhaps one group gets the prime spot because they are more aggressive than the other. Maybe the top of the tree is more exposed to nocturnal avian predators (Great-horned Owl, maybe?) and the lower/interior branches are the prime spots. You also have to take into account that cormorants are clumsy birds when on their feet. It could be that they're best bet of roosting is just landing at the top, whereas an egret can move around more in the interior.

Also, cormorants have to stretch out their wings in order to dry them because they lack the oil gland that protects feathers (preening feathers as ducks do), which is why you see them sunning themselves. So, in this scenario, I have a feeling that the cormorants are to the trees first in the afternoon, at the top, catching the last bit of sun to dry their feathers before nightfall.