What eats sword fern?

Answer 1

Sword fern are evergreen ferns native to Northwestern United States. Therefore, as plants, they don't "eat" per se, but grow, so:

The favored habitat of this fern is the understory of moist coniferous forests at low elevations. It grows best in a well-drained acidic soil of rich humus and small stones. Sword ferns are very tough, and can survive occasional dry periods, but do well only with consistent moisture, light sunlight, and prefer cool weather to overly warm. In cultivation, they also respond well to regular, light applications of
fertilizer. 1

1 http://en.wikipedia.org/wiki/Sword_fern