No, birds are survivors and won't starve if you go on vacation or even down south for the winter. You can have someone fill your feeders when you're on vacation, but don't worry if that's not possible. Birds usually follow a circuit each day, visiting a number of feeding areas. However, birds that come at dusk on a cold evening are hungry, and it's nice to make sure that they always find something to eat in the yard.
That could also mean nut or berry bushes and trees to supply a natural food source. Or allowing native flowers, such as coneflowers, black eyed Susan's, and cosmos go to seed and stand through the winter. These all provide food for the birds. A habitat that provides naturally for wild birds is a very relaxing place for people, too.