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Originally published March 31 2014

Birds don't just disperse seeds when they eat fruits - They can also spread seeds stuck to the mud of their feet

by David Gutierrez, staff writer

(NaturalNews) Due to their ability to traverse vast distances in short periods of time, birds are among the most effective of all animal seed dispersers. Perhaps the most well-known method by which birds disperse seeds is through eating juicy fruits, such as berries. The bird digests the fleshy part of the fruit and then defecates the seeds out at a different location far from the parent tree.

Many plants have evolved highly specialized methods to encourage birds to eat their fruits for just this reason. For example, some plants appear to produce berries loaded with antioxidants that birds crave before a long-distance migration. Likewise, the burn in chili peppers is designed to deter mammals (which are more likely to chew up and destroy seeds) but cannot be felt by birds at all! Mistletoe, which grows in the branches of other trees, has evolved seeds that stick to a bird's beak until scraped off on a branch.

Even some seed-eating birds, such as jays, play an important role in seed dispersal. Like squirrels, many birds will create buried caches of seeds to carry them through a season of food scarcity. However, if any of the buried seeds don't get eaten (if the bird dies, loses track of a seed or simply never gets around to eating it), it may germinate into a new tree. Recent research suggests that many plants may actually have evolved to encourage such seed predators, rather than discourage them.

Finally, birds may carry seeds on their bodies. Small and barbed seeds may get attached to the feet of birds or even to their feathers. Remarkably, birds may even carry large quantities of seeds in the mud stuck to their feet. In On the Origin of Species, Charles Darwin writes that he had been sent the leg of a red-legged partridge that had been preserved for three years, with a "ball of hard earth... weighing six ounces" still stuck to it. Testing out his theories of seed dispersal, Darwin broke up and watered the ball. To his surprise, a total of 82 plants sprouted, consisting of at least five different species.


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