Whats REALLY toxic to free range chickens?

There are numerous lists of plants that are toxic to chickens.
Sure you could throw any of the listed no-no plants to confined chickens that they would eat and be poisoned by IF those were their only greens available.

But when chickens are free to roam, they are not forced to eat these plants.
So that begs the question, what could actually sicken or kill a chicken just by a passing peck?
Is there anything you know of that is both super tasty to chickens and super deadly that they just couldn't resist?

My personal example: I found that Crown Vetch would be ideal for a roadside slope planting for a site on my property, except for the "toxic to chickens" part. They have plenty more acreage to browse so I'm trying to decide if this is even an issue.  

I'll be interested to hear of any plants that are that toxic.  So far my chickens haven't run into trouble.

Side note, crown vetch is listed as an invasive here in WI, maybe for your state too?  So depending if you worry about things like that, it could make it less ideal for your site goals.

I don't know if crown vetch and hairy vetch are closely related, but I grow hairy vetch specifically to feed my chickens.  They love it.  I've been feeding it to them for at least three years, so I don't think it's toxic.  When they are free-ranging, they seek it out.

I think that animals are very good at not eating stuff that will kill them unless, as you pointed out, that was the only thing available to them.  After my (mis)adventures in free-ranging, I penned my chickens in a good sized run.  I would let them out most evenings and watch what they did.  They almost always went for the weeds first, then went through the garden looking for bugs, then ate some grass.  They always had to pass by my rhubarb to get out of the run.  Most of the time they ignored it, but sometimes they'd eat a bunch of the leaves.  

Google the toxicity of rhubarb and you'll find lots of people saying it's poisonous.  Like anything, dose comes into play, but my reading suggested that they would eat it if their parasite load got elevated.  I never wormed them, though I treated them very well, and they laid 5 eggs a week for 3 years with no disease.

From a management viewpoint, if you've got a hen that eats poisonous plants, you won't have that problem with her for long, and it makes it easier to not select her for breeding.  I think that those bloodlines were closed long ago.  If you've got a lot of variety, you probably don't have to worry about them eating toxic stuff.  That may not hold up in an intensively managed grazing environment for larger animals, due to the perceived scarcity of food and the competition it evokes.

Trace Oswald wrote:I don't know if crown vetch and hairy vetch are closely related, but I grow hairy vetch specifically to feed my chickens.  They love it.  I've been feeding it to them for at least three years, so I don't think it's toxic.  When they are free-ranging, they seek it out.

Apparently Crown Vetch is not a true vetch like the others that are grown for fodder. For one thing, Crown is a perennial. Pesky plant naming.  

Mike Jay wrote:I'll be interested to hear of any plants that are that toxic.  So far my chickens haven't run into trouble.

Side note, crown vetch is listed as an invasive here in WI, maybe for your state too?  So depending if you worry about things like that, it could make it less ideal for your site goals.

It is listed as invasive here in MO too, though of less concern than some others and pretty well naturalized at this point. It is extremely prevalent on the roadsides nearby (which are exploding in their pink flowers) so I'm kinda thinking, why not embrace it on my roadside slope by digging some up and moving it for free? I considered using nice natural Virginia Creeper until I realized just how insanely far it can travel underground and persist by popping up anywhere.

Trace Oswald wrote:I don't know if crown vetch and hairy vetch are closely related, but I grow hairy vetch specifically to feed my chickens.  They love it.  I've been feeding it to them for at least three years, so I don't think it's toxic.  When they are free-ranging, they seek it out.

Interesting! I recently read that specifically the seeds are toxic to chickens. Are your chickens getting hairy vetch seeds, or just nomming the plants before they get to that point?

(Source: https://www.westcoastseeds.com/products/hairy-vetch-6)