The lady fern poisonous?

[chickity-chick]

Is the Lady Fern species of fern poisonous to chickens? My birds ate some in my yard and I’m worried. Or can this species of fern be a good treat for them? Not sure where to post this. Thank you!
Edit: I found this about them. Is this bad for chickens?!

Lady fern leaves and rhizomes contain a chemical called filicic acid. Filicic acid is used in treatments for parasites such as tapeworms. In low amounts, it will likely not harm dogs, but large quantities will have a toxic effect. Symptoms of a filicic acid overdose includes convulsions and potentially death.

 

[azygous]

People consume the fiddleheads cooked or in salads, so it can't be that toxic. I've noticed that chickens will most often ignore toxic plants they encounter. If they taste it and it tastes disagreeable, they won't eat it again. I doubt the small bit your chicken ate is going to harm her.

To compare, take the tomato plant. It's in the Nightshade family that includes some wildly poisonous plants that even a little bit can kill humans. The tomato leaves are supposed to be toxic to chickens, but my chickens happily nibble them given the chance with no ill effects. It's likely the lady fern is similar, slightly toxic but not terribly poisonous.