Seagull, Gull Management

Reasons for Management and Moving Birds

There are a variety of reasons for managing urban bird pests. These reasons generally involve health, safety or saving money, or a combination of these.

Human disease transmission

Birds are associated with dissemination of the causative agents of a large number of diseases that can affect the health of humans. There are more than 110 pathogens (8 virus, 55 fungi, 41 bacteria, 6 protozoa) reported to affect pigeons. Scientific papers implication wild birds in the dissemination of zoonoses are easily found. These studies give pest controllers ample reasons for arguing that birds and their droppings can be a hazard to public health and that bird management could help in preventing the spread of disease. However, reports of actual cases of human diseases transmitted from birds are relatively rare (though it is likely that the majority of cases go unreported).

These zoonoses can be broadly divided into three categories: air-borne, food-borne and insect-borne disease.

Air-borne disease

Air-borne disease agents can be either pathogenic microorganisms or dust. The resulting illness can be severe, and convalescence very drawn out, possibly extending to months and death is a possibly. Causative agents that can be inhaled and the symptoms exhibited include:

• Chlamydia psittaci– bacteria found in the viscera of infected birds. It is excreted in the faeces and found in nasal and eye secretions, thus contaminating the birds’ feathers, faeces and nesting materials. Human infection is called ornithosis and symptoms include chills, fever, sweating, severe weakness, headache, blurred vision, pneumonia, possibly death. Bird management techniques in the UK have suffered acutely from this disease, with chronic problems continuing for years afterwards. It is not always possible to link exposure to infect birds- the source of the majority of human infections in the UK is not identified. However, according to the U.S. Centre for disease Control and Prevention, feral pigeons served as the source of infection in 19% of 236 cases of human ornithosis.
• Cryptococcus neoformans – yeast found in accumulated bird droppings. It appears to be gaining in significances in the UK. For most people, infection can appear to be little more than a bout of ‘flu’ but, in susceptible individuals (with damaged or suppressed immune systems), severe systemic infections including pneumonia and meningitis can develop, leading to prolonged hospital stays and sometimes even death.
• Histoplasma capsulatum – fungus found in accumulated bird and bat droppings. It is dimorphic, being a yeast when warm and a mould in cooler temperatures. It is of particular significance in north America, though it is also found in other parts of the world. As with cryptococcosis, most people would be unaware they had caught histoplasmosis, bit it can lead to hospitalization and even death with a small number of particularly susceptible individuals. Symptoms can include fever, chest pains, cough, pneumonia and meningitis.
• Allergenic particles – an allergic condition known as bird fancier’s lung (extrinsic allergic alveolitis). It occurs among bird keepers and people exposed to airborne antigens in dust inhaled from bird infested areas. It can take two forms: acute or chronic. The acute form can lead to intense flu-like symptoms of fever, chills, muscle ache, cough, breathlessness. Onset of the acute form usually occurs 4 to 8 hours after exposure to the allergen, but it can strike many years after exposure. It usually lasts less than 48hours, though can last up to a week or more. The acute phase may be followed by the chronic phase, which is characterised by pulmonary fibrosis, a type of irreversible lung damage. The symptoms include breathlessness on exertion, cough and weight loss. In extreme cases it may be fatal.

Food-borne disease

Food-borne disease is mainly caused by bacteria that can live on the food. The resulting illness from these organisms will generally take the form of infections or food poisoning, though in immune-suppressed or susceptible individuals it might even lead to death. Illness usually occurs shortly after ingestion and is over relatively quickly, though in the case of Listeria incubation can up to 6days. The incidence of these illnesses being directly transmitted by birds is thought to be low.

Pigeons have been shown to be carrying the same strains of bacteria affecting local people, suggesting a link. Food-borne bacteria might be spread to humans if you have poor standards of personal hygiene after contacting droppings, but the potential for birds to contaminate human food directly is generally rather limited. Gulls feeding at contaminated sited, such as sewage treatment works and sewage outfall pipes, can pick up food poisoning bacteria and pass them out with their droppings on grazing pastures, water reservoirs and other sites significant in the human food chain. Jackdaws and Magpies have been implicated in the transmission of Campylobacter when pecking milk bottles. House sparrows have been shown to carry Salmonella so, if they are infesting a warehouse or a supermarket, there is a potential for them to spread disease through droppings. Starlings, Sparrows, and pigeons can infest livestock buildings and units where animal food is handled in bulk. The presence of birds here can pose a serious potential health hazard.

In the UK, allowing birds to infest a food business violates the food Safety (General Food Hygiene) Regulations 1995, and could result in prosecution of the food company.