Wild Bird Diseases Found in UK PopulationsAs mentioned on our Wild Bird Care page, diseases are a prominent concern for UK vets and bird enthusiasts, and they are only becoming more and more common amongst garden bird populations. This means that we must take extra care to ensure hygienic feeding methods, keeping an eye out for the symptoms of wild bird diseases when feeding.
Here are some of the wild bird diseases currently seen in UK bird populations:Avian Pox
Avian pox is a relatively new (and emerging) disease in the UK, where it is becoming increasingly common amongst garden birds. The disease is caused by a thick-walled avipoxvirus, and it can take two different forms. The first is a dry, cutaneous (skin) form, which stimulates excessive skin growth and nodular warty lesions; this is the form of disease most commonly seen in our garden birds. The ‘wet’ form of the disease is more commonly seen in domestic chickens and turkeys, where the virus infects the mucous membranes of the digestive and respiratory tracts.
Below is an electron micrograph of a pox virus that shows just how thick-walled the virus is. This thick wall enables pox viruses to be extremely resistant to environmental factors (such as disinfectants), and the virus survives and multiplies extremely well in dry conditions. This is why pox lesions are seen more commonly in the summer months than the winter. Electron Micrograph showing thick walled Pox VirusMild Pox lesions around eye and on beakGreat Tit with Pox lesionsTick infested Reed WarblerSeverly infected Great Tit Currently, great tits seem to be more predisposed to this disease than other garden birds, although it has also been recognised in dunnocks, wood pigeons and blue tits, with sightings in blackbirds also recorded. In most other species, the disease manifests itself in featherless areas as scaly patches or pink/grey plaques, with birds mounting an immune response to survive the infection. In the case of the great tit, the disease can cause sizeable, wart-like nodules to develop, which may impact the bird’s ability to fly, feed, or even see! If the bird is able to feed, it is possible that it may recover with only minor scars; however, the diseases can also lead to the bird’s eventual death in the most severe cases.
Avain pox can be spread through biting flies in the summer months, as well as infected feeding stations, which is why an efficient hygiene routine is so important when feeding these birds. Although it does not seem to be infectious to humans, care should be taken when handling infected birds, which calls for gloves and thorough cleaning measures. When looking out for the disease, it is important to note that small lesions may be a result of other injuries or tick infestations.
This is a relatively new disease among British garden birds, which arises when the Protozoal parasite infects the individual, by surviving in moist conditions. Unlike Avian Pox, in most cases, a bird infected with Trichomoniasis will not survive. Flagellate protozoan parasitesCanker caused by T.gallinaeHealthy Greenfinch. Courtesy S TranterOne not so luckyCourtesy Norwegian Veterinary InstituteDirty Birdbaths facilitate transmissions This was a significant problem for pigeons and doves during the 1970s and 1980s, causing them to suffer with nasty necrotic ingluvitis, which refers to an inflammation of the crop and oesophagus. While the disease is still seen in game and poultry, the development of in-water antibiotics means that it is now less commonly diagnosed in pigeons, although this has not been good news for the UK’s garden birds.
For some unknown reason, the parasite (often referred to as Canker), jumped host group, to have a dramatic impact on the UK’s wild finch population. This has been witnessed most severely in the case of the Greenfinch, with the impact of the disease at its worst during the period between 2006 and 2007. Other cases were also recorded in Chaffinches, Collard Doves and Wood Pigeons, along with a small number of recorded instances among other garden birds.
The disease results in an inability to swallow, which causes a build-up of excessive saliva. This leads to wet facial and chest plumage, as well as breathing difficulties and emaciation. Due to the fact that it lives in the upper digestive tract, it is likely that the disease will be spread between hosts by saliva, which can occur during courtship and feeding routines, as well as via saliva-contaminated water and food.
Diseased finches will usually appear puffed up and lethargic, in an effort to conserve energy. If spotted in your garden, it is highly advisable that feeding efforts should cease for at least 14 days, and preferably 21. During this time, bird baths and feeders should be scrubbed and left to dry, in order to prevent the breeding and circulation of the disease amongst the population.
The rod-shaped bacteria of this disease means that they are zoonotic, which allows them to spread from animals to infect humans. The most commonly isolated strains of Salmonella identified in UK wild birds, are Salmonella Typhimurium DT40, DT56 and DT160. The most commonly affected species seemed to be flocking birds such as Greenfinches, Chaffinches and House Sparrows, with male Greenfinches much more frequently diagnosed than females. Salmonellosis TyphimuriumLabelLabelLabelLabelLabel Salmonella organisms invade the digestive tract of these birds, causing ulceration of the crop and oesophagus, as well as inflammation of the intestines, which leads to diarrhoea. Infected birds will display puffiness, and will often sit on the ground or on feeding perches, failing to respond to potential danger. The risk of transmission is at its greatest where large number of birds gather to roost or feed, with poor hygiene at feeding stations often facilitating an outbreak, as a result of infected droppings. While most infected birds will die, some infected individuals will act as carriers, without displaying any symptoms.
Due to the zoonotic risk associated with Salmonella, it is vitally important that good personal hygiene is exercised when cleaning feeders and water containers. Gloves should be used when handling sick or dead birds, followed by a thorough washing of hands and arms. To prevent disease in your garden, simply follow the feeding guidelines highlighted on our Wild Bird Care page .
As part of the ongoing effort to study and record wild bird diseases amongst our garden populations, Lesley would be very grateful for any photographs of diseased birds that you may have. Simply send them to firstname.lastname@example.org, along with any additional details you are able to provide. For every image used on our website, we will send you a £5 gift voucher to spend with us!