Toxins in the Environment: What Kills Chickens?

Reading Time: 7 minutes

Curate your free range flock’s environment and eliminate what kills chickens, ducks, and other backyard poultry and learn how to flush poisoned birds.

Poisoning is relatively unusual in backyard poultry, especially if you use common sense in keeping your flock away from pesticides, herbicides, rodenticides, fungicide-treated seed (intended for planting), wood preservatives, rock salt, and antifreeze. Poisoning may be the result of misguided management. Common sense tells you not to put mothballs in your hens’ nests in an effort to repel lice and mites, since naphthalene is toxic. And not to spray for cockroaches or other pests where your chickens might eat the poisoned insects. And not to put out bait to kill garden pests such as slugs, snails, or earwigs where your ducks might find it. The environment contains plenty of potential poisons without your help.

What Weeds Kill Chickens?

Some weeds found in pasture can be toxic, but should not be a problem if your flock has plenty else to eat. Most toxic plants don’t taste good and therefore are not tempting to eat, except to a starving bird. Since birds nibble here and there to get a variety in their diet, if they do get a bite or two of a toxic leaf or seed, it’s unlikely to create a problem. Then, too, whether or not a specific plant is toxic may vary with its stage of maturity, growing conditions (such as drought), and other environmental factors. Even if a bird does get a potentially toxic dose, the effect depends on the bird’s age and state of health. Some mushrooms are toxic, as well, but mushrooms would have a hard time getting a foothold where poultry are active.

Plants Potentially Toxic to Poultry

Black Locust Robinia pseudoacaia
Part: sprouts, leaves, pods, seeds
Symptoms: weakness, diarrhea, depression

Black Nightshade Solanum nigrum
Part: immature berries
Symptoms: diarrhea, irregular movements, paralysis, death

Bladderpod, Bagpod Sebania vesicaria
Part: seeds
Symptoms: bluish comb and wattles, diarrhea, prostration

Castor Bean Ricinus communis
Part: bean
Symptoms: diarrhea, progressive paralysis

Corn Cockle Argostemma githago
Part: Seeds
Symptoms: rough feathers, diarrhea, slow growth

Crown Vetch Coronilla varia
Part: leaves, stems, seeds
Symptoms: incoordination

Death Camas Zygadenus spp
Part: leaves, flower, stem, bulb
Symptoms: diarrhea, salivation, muscular weakness

Jimsom Weed, Thorn Apple Datura stramonium
Part: all parts
Symptoms: loss of appetite, reduced egg production

Milkweed Asclepias spp
Part: leaves
Symptoms: incoordination, convulsions, death

Oleander Nerium oleander
Part: all parts
Symptoms: weakness, diarrhea

Poison Hemlock Conium mculatum
Part: all parts
incoordination, paralysis, death

Pokeberry Phytolacca americana
Part: berries
Symptoms: diarrhea, convulsions

Potato Solanum tuberosum
Part: green tubers, raw peels, sprouts
Symptoms: incoordination, prostration

Rattlebox Daubentonia punicea
Part: seeds
Symptoms: diarrhea, depression

Vetch Vicia spp
Part: pea
Symptoms: convulsions

Water Hemlock, Cowbane Cicuta spp
Part: all parts
Symptoms: incoordination, paralysis, death

Yew Taxus spp
Part: leaves, seeds, twigs
Symptoms: bluish combs and wattles, labored breathing, incoordination, prostration

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What Naturally Occurring Toxin Kills Chickens?

Toxins in the Environment What Kills Chickens

Another naturally occurring potential toxin in the environment is selenium. Chickens and other poultry need selenium in their diet, but an excess of selenium increases susceptibility to salmonellosis. Grains grown in the Great Plains of Canada may be naturally high in selenium, because the soils there contain an excess of this mineral.

The organism that causes botulism naturally lives in soil and commonly occurs in the intestines of backyard poultry without causing disease. But when the Clostridium botulinum bacteria multiply in the carcass of a dead bird or other animal, or in a rotting cabbage or other solid vegetable, they generate some of the world’s most potent toxins. Birds become poisoned after pecking at the rotting organic matter or maggots feeding on it, or drinking water into which the rotting matter has fallen.

A poisoned bird gradually becomes paralyzed from the feet up. Initially, the bird sits around or limps if you force it to move. As the paralysis progresses through its body, the wings droop and the neck goes limp, giving the disease its common name limberneck. By the time the eyelids are paralyzed, the bird looks dead, but continues to live until either its heart or respiratory system become paralyzed.

If the bird isn’t too far gone, you might bring it around with botulinum antitoxin available from a veterinarian or by using a flush. Prevent botulism by promptly removing any dead bird or other animal you may find in the yard, by sorting out rotting fruits or vegetables before feeding kitchen scraps to your flock, and by cleaning out excessive droppings and other decaying organic matter from a pond for waterfowl.

Blue-green algae poisoning resembles botulism. It is rare in chickens, but more common in waterfowl. It is caused by so-called blue-green algae, which looks like algae but in reality is a type of bacteria known as cyanobacteria that produce toxins collectively known as cyanotoxins. During warm (72°-80°F), dry, low-wind days the proliferation of these bacteria results in the appearance of bloom or waterbloom consisting of dark green, bluish green, or brownish green surface scum in a shallow inland lake, pond, or slough. A bird drinking the contaminated water will die within minutes. Waterbloom requires a high concentration of nutrients. Prevention, therefore, involves minimizing nutrients by keeping fertilizer away from the water, preventing runoff from poultry and other livestock manure, and properly maintaining your septic system to prevent nutrients from leaching into the water.

Chick Poisoning

Chicks are especially susceptible to certain toxins, including:

Carbon monoxide when being transported in the poorly ventilated trunk of a car (chicks die)

Disinfectant over-use, especially in a poorly ventilated brooder (chicks huddle with ruffled feathers)

Fungicide on coated seeds intended for planting (chicks rest on hocks or walk stiff-legged)

Pesticide used to rid housing of insects (chicks die)

Rose chafers (Macrodactylus subspinosus), a type of beetle found in late spring and early summer in eastern and central North America (chicks become drowsy, weak, and prostrate, go into convulsions, and die or recover within 24 hours)

Nitrofurazone, an antibiotic used to treat some bacterial diseases (chicks squawk loudly, move rapidly, fall forward)

Coccidiostats (nicarbazin, monensin, sulfaquinoxaline) added to water in warm weather, when chicks drink more and may obtain an excessive, toxic dosage.

Although chicks are more susceptible to toxins than mature birds, brooding them in a properly managed environment will protect them from poisoning.

Toxins in Feed

Toxic seeds are sometimes accidentally harvested along with feed grains. Such seeds include:

  • Crotalaria, also known as showy crotalaria or rattlebox (Crotalaria spectabilis) — causes a rapid drop in egg production, emaciation, and death in laying hens and droopiness, huddling, and death in growing birds.
  • Coffee weed, also known as coffeepod or sicklepod (Cassia obtusifolia) — causes a drop in egg production in laying hens and reduced weight gain in growing birds.
  • Coffee senna (Cassia occidentalis) — causes weight loss, diarrhea, paralysis, and death.
  • Jimsom weed (Datura stramonium) — causes nervousness and sudden death.

Fungal poisoning can be the result of by-products generated in moldy feed. A number of poisons, or mycotoxins, are produced by molds that grow naturally in grains, and some molds generate more than one kind of poison.

Aspergillus flavus, the same fungus that causes aspergillosis, also causes aflatoxicosis, a disease that increases a bird’s susceptibility to heat stress and infection.

Fusarium sporotrichioides, along with other species of Fusarium, causes fusariotoxicosis, a digestive disorder that interferes with egg production, growth, and feathering.

Claviceps purpurea produces a highly toxic alkaloid that causes ergotism, the oldest known mycotoxicosis, characterized by shriveled combs, sores on legs, convulsions, and death.

Aspergillus spp and other fungi generate ochratoxin, one of the most poisonous of all mycotoxins. The fungi that cause ochratoxicosis prefer high temperatures that, unlike ergot and fusarium molds, thrive in pelleted feed, which is manufactured under intense heat. Most feed companies include mold inhibitors in their formulas for pelleted rations.

All mycotoxicoses increase a bird’s need for vitamins, trace elements (especially selenium), and protein. Poisoning is difficult to identify and diagnose, in part because the feed may contain more than one kind of mycotoxin. A positive diagnosis usually requires analysis of the feed to identify any fungi present. Owners of backyard poultry generally buy feed in small quantities and would most likely use up a given batch before thinking of having it analyzed. Once the contaminated feed is removed, birds usually recover.

Preventing feed from getting moldy is more problematic for waterfowl than for chickens and other upland birds. Ducks and geese, especially young ones, tend to get water in their feed, and in warm weather, moist feed goes moldy fast. Avoid fungal poisoning by making sure waterfowl feed troughs are emptied and wiped clean daily.

To prevent mold from forming in stored feed, keep it away from humid conditions and use plastic containers rather than metal ones, which generate moisture by sweating. Never give your flock any feed that has gone moldy. If you discover you have bought a bag of moldy feed, take it back and insist on a refund.

Fungal Poisoning Signs and Symptoms

Caused by: Aspergillus flavus and other fungi
Grain source: All grains

Caused by: Claviceps purpurea
Grain source:wheat, rye, cereal grains

Caused by: Fusarium sporotrichioides and others
Grain source:corn, wheat, barley, millet, safflower seed

Caused by: Aspergillus ochraceous and other fungi
Grain source: barley, corn, sorghum, wheat


When a bird suffers from food poisoning or an intestinal disease, you can hasten its recovery by flushing its system with a laxative that absorbs the toxins and removes them from the body. Although Epsom salts (magnesium sulfate) make the best flush, birds don’t like the taste and won’t readily drink it, therefore must be treated individually. If a number of birds are involved, or handling them would cause undue stress, use molasses in a flock flush. Flush only adult birds, never chicks.

Epsom salt flush: one teaspoon Epsom salts in 1/2 cup water, poured or squirted down the bird’s throat twice daily for two to three days, or until the bird recovers.

Molasses flush: one pint molasses per five gallons water, given for no longer than eight hours.

Found Objects

Small objects carelessly tossed into a poultry yard can cause distress or death. Cigarette filters, for instance, can cause impaction. Ducks and geese are attracted to small shiny objects like nails, pop tops, and bits of glass or wire. Eating one of these sharp objects may simply irritate the bird and cause depression, but may instead result in a blockage that interferes with digestion, or cause an internal tear that becomes infected. Prevent such possibilities by meticulously picking up foreign objects found in your poultry yard and ask visitors not to toss them on the ground.

Originally published in the June/July 2008 issue of Backyard Poultry and regularly vetted for accuracy.

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