canker blocks the throat of birds
- Size
- Microscopic
- Lifespan
- Short-lived outside host. Persists in moist conditions.
- Diet
- Protozoan parasite on avian digestive tract.
- Habitat
- Protozoan parasite causing canker in birds.
- Range
- Throughout New Zealand, especially urban areas.
- Endemism
- Introduced
- Main Threats
- Saliva transmission. High-density feeding sites favour spread.
- Population
- Emerging threat in native passerines and raptors.
- Conservation Status
- data_deficient
- Human Risk
- harmless
- Handling Note
- maintain hygiene at bird feeding stations to reduce transmission
- Conservation Note
- Emerging protozoan parasite in native passerines and raptors; spread facilitated by high-density urban feeding sites and managed through public hygiene awareness.
- Te Ao Māori
- The spread of Trichomonas gallinae highlights the risks of supplementary feeding. While well-intentioned, unclean feeders can become disease hubs. Conservationists urge responsible practices to protect native birds. The disease serves as a reminder that human interaction with wildlife carries unintended consequences. Vigilance and hygiene are key to mitigation.
In 2008, greenfinches and chaffinches began dying in large numbers across Britain. The culprit was Trichomonas gallinae, a protozoan parasite that causes canker. It had jumped species. Now it is in New Zealand. This single-celled organism lives in the upper digestive tract of birds. It causes necrotic lesions in the mouth, throat, and crop. Infected birds struggle to swallow. They become emaciated and dehydrated. Death is slow and distressing. The parasite is transmitted through saliva, often at shared feeding stations or water sources. It can also be passed from parent to chick during regurgitation. Native birds like tūī and bellbirds are susceptible. Raptors like falcons can contract it by eating infected prey. The disease is particularly dangerous in high-density populations. Urban gardens, with their concentrated bird feeders, are ideal breeding grounds for the parasite. Climate change may also play a role, as warmer temperatures favour protozoan survival. Management involves strict hygiene. Clean feeders regularly. Remove them during outbreaks. Provide fresh water daily. The parasite is invisible until the damage is done. The bird sits on the branch, head tilted, unable to swallow. It is a quiet end to a noisy life. The feeder hangs nearby, full of seed, a trap disguised as kindness.