I volunteer at a bird banding/fall migration monitoring station. Many bird species gorge on blackberries during their layovers, including Robins, Swainson's and Hermit Thrushes, Black-Headed Grosbeaks, Song Sparrows, House and Purple Finches, etc. It's obvious from the staining around their bills and their excrement.

Megan Lyden
Bellevue WA