The fruits of Poison Ivy are grapelike clusters of tiny, white, pumpkin-like seeds with an off-white or pale yellow rind. The photo below was taken in mid-November and shows that the rind dries out and flakes off eventually. The fruits also contain urushiol, but that does not stop the birds from eating them! Flickers and other woodpeckers are fond of them, along with sapsuckers, thrushes, pheasants and quail. The rind provides food to the birds while the seeds usually pass on through their gut unharmed and, in this way , birds are the agent for dispersal of Poison Ivy seeds.Poison ivy fruits are an important food source for a wide variety of birds (who also spread the seeds), and also for other wildlife, including deer. Goats quite like poison ivy and can be an effective means of controlling it. I've heard that drinking the milk from such a goat might desensitize a person, though I haven't seen any evidence to back that up. Studies have been done showing that urushiol is not transferred to the milk, but whether its metabolites are present seems to be unknown. A secondary consequence of birds' eating the poison ivy berries is the passage of the poison ivy seeds through the birds' digestive systems. The seeds, then, are energetically dispersed throughout the active range of the birds.
How it happens: the birds find the white poison ivy berries good eating. As a result, the non-digestible seeds end up, nicely fertilized with bird droppings, under the birds' roosting places. This works for the birds and the poison ivy. In the deep shade of the forest, poison ivy seedlings don't crowd out other plants, which works for the eco-system. However, give too many seedlings a (human-made) place in the sun, and they'll take over. This works for the birds and the poison ivy but not for the rest of us.How it happens: the birds find the white poison ivy berries good eating. As a result, the non-digestible seeds end up, nicely fertilized with bird droppings, under the birds' roosting places. |
