Ornamental small deciduous trees and shrubs lose their leaves in winter, so they're only at risk of being devoured during the growing season. There are quite a few choices in this category, but I have a few favorites that are reliably left alone, and that have other qualities that make them interesting and valuable additions to the landscape.
Flowering quince (Chaenomeles speciosa) is a thorny shrub which flowers in very early spring and you can cut branches in late winter to force indoors. Amelanchier or Shad (Amelanchier hybrids) is a multi-stemmed small tree with delicate white flowers in early spring, juicy berries beloved by birds in summer, beautiful fall color and showy bark in winter.
Of course, nothing can beat American dogwood (Cornus florida) for beauty in the spring, and new cultivars are becoming available that are much more disease resistant than the species.
I also love I also love the less commonly planted enkianthus (Enkianthus campanulatus), fothergilla (Fothergilla gardenii) and Virginia sweetspire (Itea virginica) - all have spring flowers and spectacular fall color. And viburnums are versatile yet beautiful, so I use them often. Both doublefile viburnum (Viburnum plicatum v. tomentosum) and fragrant viburnum (e.g. Viburnum carlessii and other cultivars) have beautiful flowers, a dense habit, berries and good fall color. ■
Enkianthus Fall color