My book says they prefer fruits, earthworms, insects. The book says raisins and fruits at the feeder.
Plants they'll eat from: cherry trees, strawberry patch, mulberry, pyracantha, mountain ash, chinatree berries, japanese and american barberry, honeysuckle, juniper, russian olive, grapes, cotoneaster fruit, virginia creeper, black gum, currant, date palm, persimmon, american beauty berry, bittrsweet, euonymus, sumac, madrone, cranberries, cabbage palmetto, camphor tree, pepper tree, chokecherries.
They also eat flies, caterpillars, spiders, grashoppers, ants, weevils, tiny fish.
Robins like their fruit over-ripe, where they get drunk on them.
This is from a book I have: The backyard bird-lovers guide by Jan Mahnken.
Oh - and the book says that they are very attracted to birdbaths - that they are more likely to come to a bird-bath than feeder - you might attract them to near the food with a heated birdbath.
I bought a mix that had freeze dried insects in it one time that they'd probably like - It was called Beetle Mania Mix.
http://www.favoritebirds.com/cat1.beetle-mania-mix/I think they are here pretty much year round cold and all (St. Louis)
Meg