Some plants are only poisonous to chickens during part of the growing season. Free-range chickens spend hours each day searching for food. Often much of their diet consists of plant parts and seeds, but some are dangerous plants that could harm them.
Consumption of certain plants may lead to a variety of health problems including death. Eating some poisonous plants over a period of time leads to chronic toxicity.
Depending on the type of plant, symptoms may include diarrhea, convulsions or changes in respiration or pulse. Other plants produce an acute toxicity that can kill chickens quickly.
Plants with Attractive Flowers
The atamasco lily (Zephyranthes atamasco) this dangerous plants has showy white flowers and onion-like bulbs. Its bulbs are the most toxic part of the plant for chickens. The flowers of the bladderpod plant (Glottidium vesicarium) range from yellow to purple. The bladderpod seeds are the most toxic part. White, lacy flowers top the tall poisonous hemlock plants (Conium maculatum). Its most poisonous parts are the stems, leaves and mature fruits.
Plants with Berries
The shiny black berries of the black nightshade plant (Solanum nigrum) are more toxic to chickens than the leaves. This is also true of the berries found on chinaberry plants (Melia azederach). Poultry consume the small greenish-yellow or yellow-tan berries when the berries fall from the trees in the fall.
Poisonous Shrubs or Trees
The black locust shrub or tree (Robinia pseudoacacia) grows along roadsides and in fencerows. The roots, bark, seedpods and even the young sprouts are poisonous. The rattlebox (Daubentonia punicea), another small tree or shrub, is a dangerous plants to chickens; consumption of as few as nine seeds may be fatal.
Prickly Dangerous Plants
The common cocklebur (Xanthium pensylvanicum) produces burs that cling to socks and hair. Its seeds and seedlings are considered poisonous to chickens. All parts of jimsonweed (Datura stramonium) — a plant with a large, spiny capsule fruit — prove to be poisonous.
Consumption of one ounce of Mexican poppy seeds (Argemone mexicana) often causes symptoms in chickens while two ounces will kill them. All parts of milkweed (Asclepias tuberosa), a plant that releases a milky sap from its roots, are toxic to chickens. Symptoms appear when chickens consume about 2 percent of their body weight as milkweed. The showy crotalaria plant (Crotalaria spectabilis) is toxic when consumed as green plants in fields or in dried hay. Chickens who consume about 80 seeds will die.