Complex sentence: The sunbirds and spiderhunters are a family, Nectariniidae, of very small passerine birds which feed largely on nectar, although they will also take insects, especially when feeding young.
Split into simpler sentences: The sunbirds and spiderhunters are a family, Nectariniidae, of very small passerine birds. Most sunbirds feed largely on nectar, although they will also take insects, especially when feeding young.