Chickens are resilient animals but, like all livestock, they hide the early signs of illness instinctively — a behaviour that evolved to avoid appearing vulnerable to predators. By the time an animal is showing obvious distress, the disease has often been present and progressing for days. Developing sharp observational skills during daily checks, and knowing specifically what to look for, is one of the most valuable skills a livestock keeper can develop.

This guide covers the most common and most important warning signs in chickens in Australian conditions. None of these signs is a diagnosis — they are indicators that require closer assessment, possibly veterinary advice, and prompt action.

1. Puffed up, standing apart from the flock

A chicken that is fluffed up with feathers puffed out, standing in one spot away from the flock, or sitting hunched on the ground rather than actively foraging is showing classic signs of illness or distress. Chickens in warm weather do not normally puff their feathers; a bird doing this at any temperature above about 15°C is unwell.

2. Reduced egg production

A sudden or gradual drop in egg production across the flock — not explained by moult, reduced daylight, or dietary change — is one of the most reliable early indicators of disease in laying hens. Infectious bronchitis, Newcastle disease, and reproductive tract infections all reduce egg production as an early sign, often before clinical illness is obvious in individual birds.

3. Respiratory signs — coughing, wheezing, rattling

Audible respiratory sounds — clicking, rattling, wheezing, or bubbling — in chickens indicate respiratory disease. The range of causes is significant, from the relatively manageable (infectious bronchitis, mycoplasma) to the reportable (Newcastle disease, avian influenza). Any flock-level respiratory problem should be investigated promptly by a vet — avian influenza in particular requires immediate reporting.

4. Diarrhoea

Chicken droppings are normally firm and brown with a white urate cap, though caecal droppings (produced once or twice daily) are normally brown and liquid. Persistent watery, green, or bloody droppings in multiple birds indicate disease. Coccidiosis (particularly in young chickens 3 to 6 weeks old) produces bloody droppings and rapid weight loss. Salmonella produces watery yellow-green diarrhoea.

5. Swollen face or head

Swelling of the face, particularly around the eyes and sinuses, suggests infectious coryza (caused by Avibacterium paragallinarum) or mycoplasmosis. A swollen, bluish comb and face in a hen with laboured breathing could indicate Newcastle disease or highly pathogenic avian influenza — both notifiable diseases. Report any sudden, severe flock illness with facial swelling to your state agriculture department immediately.

6. Paralysis — legs or wings

A chicken dragging a wing or one or both legs may have Marek's disease — a very common herpesvirus infection in unvaccinated flocks that causes nerve damage and paralysis. It typically affects young birds from 6 to 30 weeks of age. Botulism (from ingesting decomposing carcases or maggots from them) causes a flaccid paralysis of the neck, legs, and wings — remove all carcases from the range immediately and prevent access to decomposing organic matter.

7. Crop problems

A crop (the food storage pouch at the base of the neck) that is hard and impacted in the morning before feeding suggests sour crop or impacted crop. Normally the crop empties overnight and should be soft or empty at dawn. A distended, soft, sour-smelling crop that does not empty is sour crop — often caused by a bacterial or yeast overgrowth. Massage, fasting, and veterinary treatment are indicated.

8. Scaly leg mite

Thickened, crusty, lifted scales on the legs — particularly in older birds — indicate scaly leg mite (Knemidocoptes mutans). The mites burrow under the leg scales causing significant discomfort and, in advanced cases, lameness. Treatment is simple — smothering the legs in petroleum jelly, repeated weekly, suffocates the mites — but early treatment is much easier than treating advanced cases.

9. Sudden deaths without prior signs

Sudden death of apparently healthy birds — particularly in hot weather — can indicate heat stress and heat stroke. In summer, ensure adequate shade, cold water, and ventilation. Multiple sudden deaths with no obvious cause require post-mortem examination; Marek's disease, coccidiosis, and Newcastle disease can all cause rapid death in apparently healthy birds.

10. Not roosting at night

A chicken that does not return to the roost at night, or is found sitting on the ground rather than roosting, may be injured, ill, or affected by parasites. Check for red mite (a blood-sucking mite that lives in the coop structure and feeds on birds at night — visible as small red-grey mites on white paper in the coop) which makes roosting uncomfortable and causes anaemia in heavy infestations.

When to call a vet

Any single animal showing multiple symptoms simultaneously, any situation involving multiple animals affected at once, any sign of neurological involvement (incoordination, circling, seizures), or any rapidly deteriorating animal should prompt immediate veterinary contact. Do not wait to see if the animal improves — the time lost in delay is frequently the margin between a treatable problem and a dead animal. Keep your vet's contact number saved in your phone and know the after-hours emergency number before you have an emergency.

For more on chickens health, see our Health Guide and Poultry Care Guide.

For more, see our Keeping Chickens in Australia: The Complete Beginner's Guide and Sick Goat Symptoms: 12 Signs Your Goat Needs Attention.