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.