Juvenile eating fruits of bugweed Solanum granulosum-leprosum

I thank Gustavo, the author of the photo, for sharing this finding. It was taken during a visit of the Coa La Plata (Observers' Club) to Costanera Sur in july 2012. 
This is not the natural habitat of the Black-backed Grosbeak. Its distribution range covers a vertical stripe from the yungas up north to the Province of San Luis