For most wildlife winter presents its most serious challenge to survival; for birds this is certainly true. Many species, such as chickadees and nuthatches, for example, rely heavily on food caches they have created during the fall. All birds either supplement their stored items, or rely solely on, food that is available even at the coldest time of the year.
The fruit of Staghorn Sumac Rhus typhina provides nutrition for various bird species, notably Ruffed Grouse Bonasa umbellus and Evening Grosbeak Hesperiphona vespertina. Staghorn Sumac is so called, by the way, because its branches are velvety resembling the velvet of the new antlers of deer. In the fall the leaves of this tree assume a very attractive deep, vivid red.
Apples provide food for for those species that spend the winter with us, both as fruit, and for the grubs they often harbour within them. Woodpeckers are commonly seen hammering away at an apple to get to the protein contained therein.
The fruit of the common apple tree Malus sylvestris manifests itself in many forms, from the small apples commonly referred to as crab apples, to large fruit similar in size to that which we buy in the supermarket, or from our local orchard or farmers' market. No doubt many of these trees were seeded from apple cores tossed away by birders and other hikers through the woods.
I have seem American Robins Turdus migratorius in an inebriated state after feeding on fermented fruit. Perhaps like humans in similar condition, they just sleep it off!