We kiss under it but mistletoe is important in nature; it provides food, cover, and nesting sites for many animals. The Christmas mistletoe we hang from our doorways is only one of more than 1,300 species of mistletoe worldwide. In the U.S., we have only the American (kissing ) mistletoe and the dwarf mistletoe. The plant’s common name is derived from early observations that mistletoe would often appear in places where birds had left their droppings. “Mistel” is the Anglo-Saxon word for “feces,” and “tang” is the word for “twig.” Mistletoe thus means “feces-on-a-twig.”
Why would mistletoe be associated with bird droppings? Well, it turns out that mistletoe has a handy adaptation that provides for its dispersion. Birds eat mistletoe berries, digest the fleshy part, and excrete the seeds which are covered with a sticky coating , allowing them to adhere to a tree branch. The seeds pass rapidly through the digestive tract in 4-25 minutes, so the seeds come out unharmed and ready to germinate. The seeds then sends out roots to penetrate the tree where they start to absorb some nutrients from the tree. Mistletoe is only a partial parasite as their green leaves allow them to photosynthesize. Eventually mistletoes grow into a bushy form on a tree.
The sticky juice of mistletoe seeds was once used to capture mammals and birds by smearing it on a twig, trapping small creatures. (The Dwarf Mistletoe distributes itself with a different mechanism – exploding berries that shoot each rice grain sized seed up and away at up to 50 mph!)
Birds not only distribute mistletoe, but make more homes for themselves as the mistletoe laden trees have shorter lifespans, leading to more snags and more homes for cavity-nesting birds; three times as many according to some studies.
Grouse, Mourning Doves, bluebirds, Evening Grosbeaks, American Robins, and Cedar Waxwings and others eat mistletoe berries. The Phainopepla (photo) of the southwestern desert lives almost exclusively on mistletoe in the winter. Birds also find mistletoe a great place for nesting, especially the dense “witches’ brooms” –a clump or mass of abnormal branch and twig growth (photo). In one study, 43 percent of spotted owl nests were associated with witches’ brooms. Another researcher found that 64 percent of all Cooper’s hawk nests in northeastern Oregon were in mistletoe. Other raptors that use mistletoe as nesting sites include the Great Gray Owls, Long-eared Owls, Northern Goshawks, and Sharp-shinned Hawks. Likewise, some migratory birds— Gray Jay, Red Crossbills, House Wrens, Mourning Doves, Pygmy Nuthatches, Western Tanagers, Chipping Sparrows, Hermit Thrushes, Cassin’s Finches, and Pine Siskins find dense mistletoe appropriate for nesting.
There actually is a “Mistletoe Bird.”(See photo) It is a flowerpecker species native to most of Australia where it eats mistletoe and a variety of other foods such as berries, pollen, insects, and spiders.
Well, kiss all you might this Christmas season, but don’t eat mistletoe leaves or let your dog or cat chew on them as they are poisonous.