Bird mites (also known as avian mites or bird blood mites, most commonly Ornithonyssus sylviarum and Dermanyssus gallinae, depending on species) are small parasitic mites that feed on the blood of birds. They can also bite humans, causing itching, irritation and skin rashes. In the UK, bird mites are commonly associated with bird nests close to buildings, especially from pigeons, house sparrows and swallows. They are most prevalent in spring and summer and often become a serious problem when nests are abandoned or removed.
This article explains how bird mites are identified, where and when they occur, how infestations are detected, and how they can be effectively prevented and controlled under UK conditions.
Identification of Bird Mites
What do bird mites look like?
Bird mites are very small, measuring around 0.5–1 mm in length. They are flat, oval-shaped and have eight legs. When unfed, they appear greyish or almost transparent, but after feeding on blood they turn dark red to black. They move quickly and tend to hide in cracks, joints and crevices close to their host.
Unlike some other mites, bird mites do not live permanently on the host animal. Instead, they remain in the nest or surrounding environment and move onto birds – or occasionally humans – only to feed.
Habitat and Conditions
Where do bird mites thrive?
Bird mites thrive in warm, humid environments close to birds. They are most commonly found:
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In and around bird nests (for example pigeons, sparrows, starlings and swallows)
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Under roof eaves, on balconies and in ventilation ducts
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In hen houses, aviaries and bird enclosures
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In cracks, timber and building materials near bird nesting sites
When birds leave the nest, mites may search for alternative hosts, including humans and pets, which is often when infestations are noticed.
Signs of Infestation
How can bird mite infestations be detected?
Infestations are often detected when people experience:
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Sudden itching and skin irritation, particularly at night
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Small red bite marks on arms, legs or the neck
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Tiny dark moving specks on walls, curtains or bedding
In birds, signs may include:
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Restlessness and increased scratching or preening
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Weight loss, pale combs and reduced vitality
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Blood spots in nests or on eggs
Inspecting abandoned nests and nearby areas often reveals large numbers of mites hiding in cracks and crevices.
Life Cycle
What is the life cycle of bird mites?
Bird mites have a very rapid life cycle, which can be completed in as little as 5–7 days under optimal conditions (20–30 °C and high humidity). The life cycle consists of egg, larva, two nymph stages and adult mite.
Each female can lay up to 100 eggs. Bird mites can survive for several weeks without a host and become active quickly when a suitable host is present.
Prevention
How can bird mite infestations be prevented?
Prevention focuses on limiting nesting opportunities and protecting buildings from birds:
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Remove bird nests as soon as they are empty (outside the breeding season and in accordance with wildlife regulations)
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Install bird spikes, netting or covers to prevent nesting
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Seal cracks and gaps in buildings, especially around roofs, balconies and vents
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Clean and maintain hen houses and bird housing regularly
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Monitor buildings closely during warm months, particularly in areas with many pigeons or wild birds
Control Measures
How can bird mites be controlled?
If an infestation is confirmed, the following measures are recommended:
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Remove and safely dispose of bird nests
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Vacuum and clean surrounding areas thoroughly, focusing on cracks, skirting boards and soft furnishings
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Use an insecticide spray approved for indoor use, such as contact products containing pyrethroids or silicone-based agents
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Wash bedding, curtains and clothing at a minimum of 60 °C
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In severe infestations, professional pest control treatment may be necessary
Effective control usually requires a combination of chemical treatment and thorough cleaning to achieve lasting results.
Occurrence in the UK
Where in the UK are bird mites most common?
Bird mites occur throughout the UK but are particularly common in urban and coastal areas where pigeons and small birds nest close to human dwellings. They are frequently reported from flats and houses with balconies, lofts and roof eaves that allow easy access for birds.
Infestations typically peak between May and August, coinciding with the bird breeding season and warmer temperatures. Early detection and prompt action are key to preventing prolonged problems with bird mites.