Gastrointestinal helminthosis of common buzzard
The honey buzzard (Pernis apivorus) is a migratory raptor that feeds primarily on wasp larvae and insects, but also occasionally small vertebrates. Like many wild birds, it can host different worms housed in its digestive tract: these paras...
What is it?
The honey buzzard (Pernis apivorus) is a migratory raptor that feeds primarily on wasp larvae and insects, but also occasionally small vertebrates. Like many wild birds, it can host different worms housed in its digestive tract: these parasites live in the stomach, intestine or sometimes the crop of the bird.
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In small quantities, these worms often cause no visible signs and the bird lives normally with them. The problem occurs when the number of parasites becomes too great, or when the bird is otherwise weakened (injury, lack of food, migratory stress): the digestive system is then disrupted and the general health of the animal declines.
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:
The signs are often discreet and not very specific in this wild bird.
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We can observe progressive weight loss despite a sometimes preserved appetite, abnormally soft stools or changes in appearance, general depression with dull and disheveled plumage.
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In more severe cases, the bird may present vomiting or regurgitation, visible discomfort in the stomach, slowed growth in young birds, and pallor of the visible mucous membranes (for example inside the beak) if the infestation leads to chronic blood loss.
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Sometimes worm segments or entire worms can be spotted in the droppings upon close examination.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Several families of parasitic worms of the digestive tract can be involved in raptors, notably roundworms (nematodes) and sometimes flatworms (cestodes or trematodes), depending on the bird's diet and environment. The life cycle of these parasites often involves an intermediate host, such as an insect or small invertebrate, which the buzzard ingests while feeding.
Young age, the period of migration which depletes the bird's reserves, an already weakened state of health (injury, malnutrition), and frequent contact with prey carrying parasitic larvae increase the risk of clinically visible digestive helminthosis.
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Birds kept in captivity for care, in a restricted, shared space, can also be exposed to reinfestation if the environment is not properly maintained.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian or specialist wildlife trainer carries out a complete clinical examination and looks for parasites by analyzing the droppings under a microscope (search for worm eggs). A more in-depth examination may be proposed if the initial results are inconclusive while the clinical signs persist.
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The general condition of the bird, its weight and its hydration are assessed to judge the seriousness of the situation before any treatment decision.
Treatment
Treatment is based on the administration of antiparasitics adapted to the species and type of worm identified, under strict veterinary supervision specialized in wildlife. Supportive care (rehydration, dietary supplement) can accompany antiparasitic treatment in a weakened bird.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
In a wild bird living in the wild, direct prevention is limited since we cannot control its natural diet.
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In a care center or convalescent aviary, prevention is based on good hygiene in accommodation areas, regular cleaning of floors and feeders to limit the accumulation of parasite eggs, and parasitological monitoring of droppings during the bird's stay.
Possible complications
A heavy infestation left untreated can lead to anemia, dehydration, general weakening compromising the bird's flying and hunting abilities, and even death, particularly if combined with other health problems or the stress of migration.
When to see a veterinarian
Discovery of a emaciated or apathetic bird during treatment in a care center.
Presence of worms visible in the droppings.
Persistent diarrhea or abnormal stools in a collected bird.
Pale mucous membranes or marked weakness associated with digestive disorders.
Growth retardation in a young bird undergoing care.
Prognosis
The prognosis is generally good if the infestation is detected early and treated by a competent wildlife professional, especially in a bird otherwise in good general condition. It becomes more reserved if helminthosis is combined with other conditions or an advanced state of weakness, common in wild birds collected in distress.
Frequently asked questions
Is a wild buzzard carrying worms necessarily sick?
No. Many wild birds harbor small numbers of digestive parasites without any signs of disease. The problem appears especially in the event of a high parasitic load or general weakening of the bird.
Can you treat a wild bird found weakened yourself?
No, medication should never be administered without professional advice. A wild bird must be entrusted to a care center or a veterinarian specializing in wildlife, who will make a diagnosis before any treatment.
How do you know if a buzzard has intestinal worms?
The only reliable way is an analysis of the droppings under a microscope carried out by a professional, which allows you to look for parasite eggs. Visible signs alone are not enough to confirm the diagnosis.
Can this disease be transmitted to humans or other animals?
Digestive worms of wild raptors are generally not considered transmissible to humans. Contact with a sick wild bird must, however, always be done with basic hygiene precautions.
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 29 September 2026
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