Recently I saw mentioned that Pine Grosbeaks prefer the seeds and often don’t eat the whole berries when foraging on Mountian Ash (Sorbus aucuparia) berries. This is contrast to American Robins, Varied Thrushes, and Bohemian Waxwings – other species seen around here that eat the whole fruit.
I have seen Pine Grosbeaks eating Mountain Ash berries several times, but hadn’t ever really noticed that they didn’t eat the whole fruit. While out looking for the Townsend’s Solitaire the day after it was found, I watched a small group of grosbeaks eating berries. There were some berry skins on the ground, and the grosbeaks generally seemed to have a bit of a mess on their bills (as seen in the picture above) – presumably from mashing the berries up to extract the seed before dropping what remains of the flesh. Perhaps now I can sometimes track grosbeak presence by noticing the berry skins they leave behind.