Those are in fact ravens. I was in Yosemite on Christmas, the day after a big snow storm to take pictures of the park. We try to go every Christmas day as we only live about a hour from the park.
We parked and went in for some lunch and when we came out the birds were digging through a bag of trash. I bought a package of hotdogs and baited them in the back of truck for pictures.
It has been a tough year for those birds with all the snow and wet weather we have been having.
If you look close a couple of those birds have three pieces of hotdog in their beak. There were at least 20 birds trying for a meal.