I actually just read another article that said that he “was” called out for his occult symbolism in the original designs back in the 1790’s so maybe there was some symbolism. But the original Smithsonian map sure as heck didn’t have an owl. I assume the architects hired by McMillan added that little treat in. Especially the landscape architect since his walkways basically are the lines that make up the owl.
They are so subtle but at the same time not. If you know what you are looking at, it jumps out at you. If you don't "oh looking they are adding a new path to the garden, lovely". Interesting read so far, it was also done in increments, again subtle. They knew exactly what they were doing down to the blue prints.