“Bright, bright the holly berries in the wreath upon the door”
So begins one of the charming Alfred Burt Christmas Carols. And indeed, the berries of holly are bright red—a Christmassy contrast to the glossy green of the holly leaves. But why?
Berries are red to increase their visibility…a natural marketing technique. You see, for plant species to survive, individuals must produce seeds. But if seeds merely dropped directly under parent plants, their chances of survival would be extremely poor. Consequently, plants have an amazing array of seed dispersal strategies.
Some seeds float on the breeze. Others float on water. Nuts and grains are distributed by busy little rodents. And then, some trees, like holly, bear fruit.
The actual seeds of most fleshy fruits are exceedingly hard. Besides being red, fruits tend to be sweet and appealing to birds. They gulp down fruits and berries whole.
This plant/animal relationship is so established that certain seeds will not germinate unless they have passed through a digestive tract of a bird. The seeds are “planted” with a bit of fertilizer, often a considerable distance from the parent plants.
Evidence indicates that most birds see the same colors we do, but that they are more sensitive to the red end of the spectrum. Not only that. Some birds also have curious little red and orange droplets in their retinas. Filters perhaps? To enhance the color red?
Probably because of holly, red and green have become the colors of the holiday season…and during the snowy part of the year, for hungry birds, bright, bright berries among the leaves of green can mean survival.
