Margot

1.  What's your evidence? 2.  In many places I've lived.  Here in downtown Portland, only occasionly are they on view at around twilight - usually in snall groups but sometimes up to 20. 3. Yes - both species but I believe behavior differs and ravens are less visible here.  I could be completely wrong 4. Crows are great for cleanup, and amusement fpr humans.  Their badgering of raptors is helpful to other birds and prey.  I've seen them badger great horned owls, snowy owls, red tails, etc/