Lichens are eaten to a small extent by deer, elk, moose, and grouse. In the Arctic, lichens become a more important food source for animals like this young woodland caribou in the Northern Rocky Mountains. In fact, several species of Cladonia (Cladina) are called caribou or reindeer lichens. These animals may eat lichens almost exclusively during certain seasons.

For many animals, however, lichens have greater importance as nesting material. The nests of hummingbirds, wood pewees, and blue-gray gnatcatchers commonly include lichens. The hummingbird nest pictured here appears to be largely made up of Parmelia sulcata, a common foliose lichen.

In fact, more than 50 species of North American birds are reported to use lichens, sometimes specific species of lichens, in their nests.

In the Pacific Northwest, lichens are used as nesting material by boreal owls and flying squirrels, among other species. Photos at Sharnoff Photos.

Lichens also have significant relationships with many species of invertebrates.

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Sources:

Martin et al. 1951. American Wildlife and Plants, A Guide to Wildlife Food Habits, Dover Publications.

Sharnoff/Brodo. Lichens of North America at SharnoffPhotos.com.
Lichens and Wildlife.