There was a big crow winging over the canyon today. He would swoop in low over the roof and appear over the deck almost out of nowhere. The hummingbirds would scatter just before he showed up, kind of like fish scatter before a shark or a large jack shows up. I don't know how they know that the crow is coming but I can only gather that crows eat hummingbirds based upon their response. I know that the crow appears to have wiped out the pigeons nesting/pooping on the eaves of the house. Actually, the crow went to the nest and wiped out the baby pigeons which seemed to be a big disincentive for momma pigeon to nest there. I could hear it's big talons clicking on the roof tiles and on the skylight. The patio is a lot cleaner now... Crows are quite carnivorous, apparently.