Parasites are by definition organisms that live off their host species without benefiting the host in any way. Most wild birds live permanently with a number of parasites, and so long as their numbers are small the host can cope with them without ill effects. When the animal becomes compromised in any way, such as by starvation, stress or illness, the parasitic load can increase to the point of causing severe illness and even death. As birds in captivity are often kept in more crowded conditions than they would experience in the wild, they can be exposed to very large numbers of parasites, which can slowly build up in the captive environment over time.
Birds can be infected by a large variety of different parasites, and it is important for us to be vigilant and to treat any infestations that may occur.
Among the more common and visible parasites are mites, lice, fleas and ticks. Poultry such as chickens are more prone to picking up these parasites as they typically come into close contact with wild birds.
Scratching (which may be severe enough to cause feather loss and even sores, especially around the head and neck) is one of the most obvious symptoms of external parasites. Other signs include:
- Scruffy, broken feathers
- Drop in egg production
Severe infestations of blood-sucking lice or ticks can cause anaemia and even death from blood loss in young chicks. A careful examination of the skin will reveal these parasites quite easily.
Treatment involves removing the source of the infestation if possible and treating both the environment and the birds (several pyrethroid- and fipronil-based sprays and powders are registered for use in birds). Fipronil spray, which is available from veterinarians and vet shops, can be used carefully under the wings and at the vent. Pyrethroid-based powders that are registered for use in birds can also be dusted through the feathers.
Intestinal worms are commonly seen and can cause problems varying from diarrhoea to weight loss, anaemia, vomiting and coughing. The most common method of infection is ingesting worm eggs from the droppings of other infected birds.
Parrots in outdoor aviaries are much more likely to have problems with worms than those kept as pets in cages. Nevertheless, we recommend deworming at least once a year. There are dewormers formulated specifically for birds. Your avian veterinarian can advise you on the most appropriate treatment.
Microscopic single-celled parasites can also cause illness in birds. These organisms cannot be seen with the naked eye and must be diagnosed by examining samples of stool or blood (depending on the parasite) under a microscope.
Coccidia, an intestinal tract infection, is spread via infected droppings and causes severe diarrhoea. It is more prevalent in outdoor birds such as poultry. Treatment is effective if the disease is caught early.
Giardia is another parasite that causes diarrhoea and can also be the underlying cause of itching and feather picking in cockatiels.
Trichomonas is very prevalent in dove and pigeon flocks and causes a condition known as ‘crop canker’. Large cheesy growths develop in the mouth as a reaction to the parasite and prevent the bird from eating and drinking. This parasite is highly infectious and is spread from bird to bird when the flock goes down to drink at a water source. Pigeons do not scoop water into the beak and throw the head back to swallow as most birds do. They have a special pharyngeal pump mechanism that allows them to suck down water without moving the head up. This pumping action of the throat unfortunately spreads the Trichomonas parasites into the water and the next-door bird will then ingest them.
Veterinarians are often asked whether anything can be done to treat garden birds for parasites, but as we have no control over exactly which food and water sources they utilise, we cannot effectively medicate them and must let nature take its course.
There are several measures that can be taken to minimise the chances of your own birds picking up parasites:
- Try to keep wild birds away from your pets. Food and water sources for aviary birds should be under a roof to prevent wild birds from soiling them with droppings.
- Any newly acquired birds should be examined by an avian veterinarian and, if necessary, treated for parasites before being introduced to the rest of your flock.
- Regular deworming should be performed and cage floors should be kept scrupulously clean so that any parasite-infected droppings are removed before they can cause problems.
In conclusion, please remember never to use any products on your birds unless they are specifically registered for such use, or unless your avian veterinarian recommends them. Medications that are perfectly safe in dogs and cats can be deadly to our feathered friends.