Sternostoma tracheacolum — the air sac mite — is one of the most common and serious respiratory parasites of budgerigars and related small psittacines. Affected birds develop a characteristic clicking or crackling sound with each breath, tail bobbing, open-beak breathing, and progressive exercise intolerance. The condition is highly treatable when caught before respiratory compromise becomes severe.
Last reviewed: June 2026
What Are Air Sac Mites?
Sternostoma tracheacolum is a tiny mite that colonizes the trachea, syrinx (voice box), air sacs, and lung parenchyma of susceptible birds. Unlike mammals, birds have a complex respiratory system of air sacs that extend throughout the body cavity and even into bone — mites that colonize this system can severely impair both gas exchange and sound production. Budgerigars (Melopsittacus undulatus), canaries, and finches are the most commonly affected species, though the parasite has been documented across many small psittacines.
As described in Carpenter's Exotic Animal Formulary, transmission occurs via direct contact with infested birds or their respiratory secretions. Newly acquired birds from pet stores or breeders with high bird density are at elevated risk. Young birds and birds under stress are most susceptible to clinical disease from what may be a subclinical infestation in carrier adults.
Signs of Air Sac Mites in Budgies
The respiratory signs are the hallmark of air sac mite infestation and reflect the mites' presence in the airways. The AAV Basic Care for Companion Birds, 2019 emphasize that any change in a bird's voice or breathing pattern warrants prompt evaluation, particularly in small psittacines where respiratory disease can progress to crisis rapidly.
Common signs:
- Clicking, crackling, or wheezing sounds heard with each breath — audible even without a stethoscope in moderate infestations
- Tail bobbing (rhythmic up-and-down tail movement synchronized with breathing effort)
- Open-beak breathing in moderate-to-severe cases
- Voice change — a budgie that previously chirped or chattered normally may become hoarse or silent
- Increased respiratory rate at rest
- Exercise intolerance — bird "huffs" or becomes distressed after minimal activity (even flying one cage length)
- Reduced activity and resting more at the bottom or low perches
- In severe cases: cyanotic (bluish) beak and feet, collapse
Infected birds may initially appear normal at rest but show obvious distress when handled or asked to fly. Careful observation during quiet handling is essential.
Diagnosis and Treatment
Diagnosis is confirmed by a transillumination technique — shining a light through the trachea in a darkened room reveals mites as small dark specks in a bird with a patent trachea. Alternatively, tracheal wash cytology, air sac endoscopy, or post-mortem examination confirms the diagnosis. An avian vet experienced with birds can often make a clinical diagnosis based on the characteristic auscultatory findings.
Treatment relies on ivermectin or moxidectin, as referenced in Carpenter's Exotic Animal Formulary. Moxidectin (topical, 1 drop of diluted solution on the skin of the neck) has gained favor for its ease of administration and efficacy. Treatment is typically repeated every 2 weeks for 3 treatments. All birds in the household should be treated simultaneously. Supportive care — warmth, oxygen supplementation for severely dyspneic birds, and stress reduction — is critical while awaiting the drug's effect.
When to See a Vet
Call your vet today if:
- Your budgie is making clicking or wheezing sounds with every breath
- Your budgie's tail is bobbing rhythmically while resting
- Your budgie has become quieter or has lost their normal voice
Go to the ER immediately if:
- Your budgie is breathing with an open beak and appears distressed
- Your budgie is sitting on the cage floor, fluffed, and unresponsive to normal stimuli
- Your bird's beak or feet appear bluish or grey
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Frequently Asked Questions
How do air sac mites spread between birds? Transmission is via direct contact — respiratory secretions, close perch sharing, or regurgitation feeding between birds. Newly introduced birds from unknown flocks are the most common source of household introduction. Quarantining new birds for 30 days before introducing them to existing birds is the best prevention.
Can air sac mites survive in the environment without a bird? Air sac mites are obligate parasites that require a avian host to complete their life cycle. Environmental survival away from a host is very short — hours to a day at most under normal conditions. Cage cleaning is still important, but the primary focus of control is treating all birds directly.
How much does air sac mite treatment cost? An avian vet exam runs $60–$120. Diagnostic procedures (transillumination, cytology) add $40–$120. Moxidectin or ivermectin treatment is inexpensive — $20–$50 per treatment course for a small bird. A full treatment course including exam and three treatment visits typically costs $200–$400.
Can humans or other mammals get air sac mites? No. Sternostoma tracheacolum is an obligate avian parasite and cannot infest mammals or humans. The only household species at risk are other birds.
How quickly do birds improve after treatment? Many birds show noticeable improvement — quieter clicking, easier breathing — within 2–5 days of the first treatment as the drug begins to kill mites. Full recovery of voice and respiratory function may take 2–4 weeks, particularly in birds with significant tracheal mucosal damage. Birds treated early have the best prognosis.
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