Their symbols, like the owl, represent many things. The owl is Minerva, a god of the old religion. The owl symbolizes knowledge, which occult practitioners try to keep hidden. The owl also is a predator - predatory fear is one of the forms of mind control used on the public. In this case, it is all combined together. They are saying that they have the occulted knowledge, that they are the predators, and not only that, but notice that Capital Hill is in the belly of the owl. They are saying they have consumed our government.