It looks like studio lighting even though I can't imagine this scene in a studio. There is incredible definition! There is a hint of pS work at the limit of his back at the lower left. Powerful general impression! The walnut is too clean to have been found outside so the impression of studio work is reinforced. It still seems to be a proud bird and that powerful beak looks capable of breaking that nut. I remember when national Geographic magazine did a series a few years ago concerning zoo babies. This photo is a little disconcerting because of the natural expression and the studio effect.
I have no photography skills, so cannot critique effectively. I am just amazed at the pluck this guy/gal has for picking such a large piece to deal with. Make my jaw sore just looking at it. I wonder... the seagulls in So. MD used to take the oysters or blue crabs they would get, fly up high and then drop them on the pavement and then dop back down to get them, all nicely opened up for eating. In the summer the causeway at Point Lookout State Park was absolutely littered with the mess from the gulls. These guys are sooooo bright, makes me wonder if something like that would be employed.
Sorry to hear that people have been reposting your pic. People do have chutzpah that's for sure.