I've never noticed these being eaten by any of our wildlife, but they may be because I've also not noticed any self-sown seedlings. Nectar producing plants can be perennials as well as woody plants, including vines, and are valuable for attracting hummingbirds, bees and butterflies. One of the plusses for the garden is that in order to produce nectar, the plants have to flower - and we all love flowers. There are literally hundreds of species and cultivars that are suitable for shady gardens. If you are in one of the hotter, southern climates, many that are said to need sun will also thrive for you in light or dappled shade.
Hummingbirds love Azaleas which are the mainstay of shady gardens on acid soil.
Most of us are familiar with the evergreen varieties, which are more accurately called Rhododendrons as true Azaleas are deciduous . Either confirm the hardiness of the plants you're considering or buy the ones you see in other people's gardens. These are evergreen in all but the bitterest of winters. There are a lot of hybrids available with flower colors ranging from white through pinks to reds to oranges. These plants flower very early in spring.