Fuel to Travel
Red berries explained
The genus Ilex, that is, the hollies, seems to like Florida, where it occurs as everything from creeping shrubs to tall trees that grow in swamps, flatwoods, and hardwood forests. Most of Florida sits on a porous, cavernous limestone bedrock that often collapses to form a depression or sinkhole. Depending on whether these hold water and for how long and when, each depression sustains a characteristic wetland vegetation ranging from live oaks to gum swamps to rings of cypress around open ponds, to pretty, compact holly swamps stocked with short trees with tiny leaves and wide bottoms standing on a spongy, dark floor.
Of these holly trees, one species commands a larger share of attention, perhaps because it is sometimes planted as an ornamental or perhaps because of its name, Ilex vomitoria, or yaupon in the Indian language. I suppose the Indians were ultimately responsible for the Latin name in some way, for they made a "black drink" from the leaves that was so high in caffeine that they used it for ceremonies, and sometimes as an emetic. Ceremonies that involve throwing up sound like a lot of fun (although, honestly, this still happens today). It is a bit reminiscent of an item I once read about uses of the (very aromatic) California bay laurel, namely, that a leaf inserted in the nostril would give one a headache. Why would somebody want a headache?
But it is likely that a second attribute of yaupon is more important than making people throw up or getting them jazzed in the morning, and that involves the dense clusters of red berries that the female trees (yes, the sexes are separate) produce every year. The red berries of several species of trees are very high in fat, and seem to have evolved as a fuel for migrating birds who need lots of energy and who are attracted to red. The birds provide a long-distance seed dispersal service for the trees, for by the time the seeds come out of the other end of the bird, the bird is miles and miles from the parent tree. The astounding scale of this bird migration has only recently been made easily visible through weather radar tracking (see video below for an example of migrations on a single night). During early spring migrations, there can be more than half a billion birds on the wing every night.
Next to our driveway stands a very large yaupon that drips with red berries every fall, berries that mostly remain on the tree until spring, apparently waiting for the northward bird migrations in the spring. All through the winter, the red berries on the dark green evergreen tree keep a sort of Christmas spirit alive, but then, suddenly one spring day, the tree flutters with hundreds of cedar waxwings, all fancy crests, Lone Ranger eye masks and yellow-banded tails. Their feeding frenzy stains our car with bird lime and dropped, fermenting berries. In two days, it is over, and the tree is bare, the ground littered with fumbles, and the birds have moved on to points north, seeking more red berries to fuel their northward flight.
Stationary as we are in space, it is hard for us to picture the world of birds that migrate thousands of miles every year, moving as a wave from south to north in the spring and north to south in the fall, taking advantage of favorable winds, and dropping out whenever the weather is bad. The tree in our driveway is only a snapshot, only one point in the birds’ time and space, a tiny dot on the huge map of their lives. I imagine a time-lapse movie of the eastern United States made from a special NASA berry-detecting satellite (how hard could that be?), in the same spirit as the migration movies on BirdCast. On a continental scale, it would show the red color of fall-ripened berries disappearing from north to south in the fall, and the winter-ripened red vanishing from south to north in the spring. What a movie that would be!
What a movie indeed. My stepfather Garland said they visited a tree in his yard in a boisterous flock and further said he observed one passing a berry to another!
It is always amazing to me that flocks of Waxwings can zero in on one, lone holly tree in one’s yard. Fascinating. My Yaupon awaits.