Question about toxic plants...

[ADozenGirlz]

Here's an excerpt from The Poultry Club of Great Britain, that details poisonous plants and toxins:
"Plants
Most poultry will avoid eating poisonous ones due to their bitter taste but birds are at risk from laburnum seeds, potato sprouts, black nightshade, henbane, most irises, privet, rhubarb leaves, rhododendron, oleander, yew, castor bean, sweet pea, rapeseed, corn cockle, clematis, common St. John’s Wort, meadow buttercup, vetch, ragwort and some fungi. Blue-green algae is quickly fatal, so water containers should be kept clean, especially in hot weather and access to stagnant water should be prevented."

Chickens will eat styrofoam if given the opportunity, so I wouldn't necessarily rely on their good judgment to ferret out things that could be harmful to them.

We have 7 chicks right now that will move to the coop in about a month. We plan/planned to free range as much as possible on our 10 acres, but I am worried about them eating something harmful to them. I have just planted lily of the valley plants as well as a clematis and both are said to be toxic to chickens. Are these things I need to remove, or do chickens naturally avoid things harmful to them? They aren't in the direct vicinity of the coop, but are definitely accessible. We have about 5 acres of woods and another 5 of lawn/field.