Gastrointestinal parasitism in woodpeckers (roundworms)
Gastrointestinal parasitism caused by roundworms (nematodes) is a common infestation in wild birds, including woodpeckers. Thread-like worms settle in the intestine or gizzard of the bird. They feed at the bird's expense and can disrupt dig...
What is it?
Gastrointestinal parasitism caused by roundworms (nematodes) is a common infestation in wild birds, including woodpeckers. Thread-like worms settle in the intestine or gizzard of the bird. They feed at the bird's expense and can disrupt digestion. This condition primarily affects young woodpeckers or weakened birds, particularly those brought to wildlife rehabilitation centers.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
An infected woodpecker may simply appear more tired than usual, with unkempt and dull feathering.
It may lose weight gradually despite maintaining an appetite, or conversely eat less.
Abnormally soft or liquid droppings are sometimes observed.
With heavy infestations, roundworms may be visible directly in the droppings.
In young birds, slower growth or development compared to siblings may be a warning sign.
In severe cases, the bird becomes very lethargic, remains inactive, and refuses to eat.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The infestation is caused by nematodes (roundworms) such as ascarids or capillaries, which colonize the digestive tract. The bird becomes infected by ingesting eggs present in the environment, on insects, or in contaminated soil and bark. Some parasite lifecycles involve an intermediate host, such as an insect, before reaching the woodpecker.
Young woodpeckers with still-immature immune systems are more vulnerable. A soiled environment, high bird density in captivity or at rehabilitation centers, stress from injury or captivity, and poor general health all promote infestation and its progression.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
A veterinarian may suspect digestive parasitism based on clinical signs, but confirmation requires microscopic examination of droppings for parasite eggs (fecal exam). A general health assessment, including evaluation of weight and body condition, completes the workup.
Treatment
Treatment relies on antiparasitic medications suited to birds, prescribed and dosed only by a veterinarian. Nutritional support and rehydration may be needed as well, particularly in weakened birds.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Good aviary hygiene and proper housing of injured birds significantly reduce the risk. Regular cleaning of surfaces, avoiding overcrowding, and appropriate diet that keeps the bird in good physical condition help reduce susceptibility to parasites. Regular veterinary check-ups of captive or rehabilitating birds are recommended.
Possible complications
Untreated heavy infestation can lead to intestinal obstruction, anemia, severe growth delay in young birds, or even death from exhaustion in birds already weakened by injury or illness.
When to see a veterinarian
The injured woodpecker shows progressive weight loss despite apparent appetite.
Worms are visible in the droppings.
The bird has persistent diarrhea.
A young woodpecker is not growing normally compared to its siblings.
The bird becomes very withdrawn or refuses to eat.
Prognosis
The prognosis is generally good if the infestation is detected early and treated by a veterinarian with wildlife expertise. Without treatment, the outcome may be poor in young birds or those already weakened by injury or other disease.
Frequently asked questions
Can a wild woodpecker transmit its worms to other birds?
Yes, parasite eggs eliminated in droppings can contaminate the environment and infest other birds, especially in captivity or shared aviaries.
Is this parasitism dangerous for humans?
No, the intestinal roundworms of the woodpecker are not considered transmissible to humans.
Can you see worms with the naked eye?
In severe infestations, some roundworms may indeed be visible in the bird's droppings, but this is not always the case.
What to do if you find a weakened woodpecker with these symptoms?
It is recommended to quickly contact a wildlife rehabilitation center or a veterinarian, without attempting to administer antiparasitic treatment yourself.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
ESCCAP — European Scientific Counsel Companion Animal Parasites
Content reviewed by the TunisieVet editorial team · Updated 02 October 2026
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