One of the tallest trees in the Neotropical rainforest, the mighty nutmeg, depends on toucans and rodents to disperse its seeds to places where they can grow. Here is a tree that can reach 150+ feet (45+ meters) in height, and without the help of rainbow-colored birds and bucktoothed mammals its seeds are doomed. What happens to small plants that grow in the forest canopy 100+ feet off the ground and don’t even have roots in the soil? Do they also need wildlife to disperse their seeds?
Mistletoe is great example of a plant that grows high up in the forest canopy and never touches the ground. Never touches the ground?? How does a plant do that? Epiphytes are those plants that grow on the surface of other plants. In a shady forest all the plants are competing for light. Some plants like the nutmeg tree win this little battle by growing head and shoulders above the rest. Other, smaller plants win by groing on the branches of trees, high up in canopy where they get all the sunlight they need. Orchids. Bromeliads. Cacti. These are just some examples of plants that bask in the sunlight on the branches of trees high in the rainforest. They get sun from above, water from the rain, and when leaves decompose around the roots that they grow along the surface of branches, they get their food. But what do these plants do with their seeds? And how did that puny plant get way up in the tree anyways? For a mistletoe, and lots of other plants, the answer is birds again.
Here is one of my favorite birds of the Neotropical rainforest, the Lovely Cotinga. This bird oozes cool! It’s a day-glow, neon turquoise blue with a plum purple throat. I bet astronauts can see these dudes from space. And yes, the actual name of the bird is “Lovely Cotinga.”
And here is the object of cotinga desire, Psittacanthus rhyncanthus, a species of mistletoe. There is nothing a cotinga loves more than to chow down on mistletoe fruits.
And herein lies our rainforest intrigue. The mistletoe, like the nutmeg, is a trickster. It puts out hundreds of small fruits that birds like the Lovely Cotinga love to eat, but this time the joke is on the birds. After a cotinga or other unsuspecting bird goes in for a tasty meal of fruits it finds out that its gullet is full of seeds, seeds that are so sticky, so gooey, it’s like having a mouthful of glue globs. To rid itself of these seeds the cotinga has to literally wipe its face across the surface of a tree branch until the seed sticks to the branch. Voila! Just like that a mistletoe is born. From branch, to bird, to branch, the mistletoe never leaves the forest canopy and is transplanted by an agent in electrified blue feathers. Stranger than fiction? That’s life in the rainforest.
Don’t believe it? You can see for yourself at places like The Lodge at Pico Bonito, Honduras, where Lovely Cotingas show up by the flockful every year during the rainy season from January to March. James Adams, a manager at the Lodge, witnessed an interesting dispute over some mistletoe between two cotingas.
James tells us: “Evidenced by the numbers of mistletoe stuck to this branch [note the little green leaves under the branch – that’s them], Cotingas have favored perches. And apparently they don’t like to share with just anyone. When this young male (note the maturing purple and blue plumage) flew in and tried to accompany this bright blue male, the older male would have none of it. And so a war of silent beak gaping ensued, with both parties opening and closing their beaks at one another, until the younger bird flew off.”
In other words, it appears from watching these colorful birds that they need the mistletoe just as much as it needs them.
Parting shot: Gotta love these guys, right?