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No Evidence of Lower Apparent Survival in Dunnocks With Avian Pox in 15.5-Year Study

Dunnock perched on a frost-covered branch
Research · Disease, parasites & microbiology

A 15.5-year study of wild dunnocks (Prunella modularis) in southwest England found no evidence that birds with visible signs consistent with avian pox had lower apparent survival than birds in which the disease was not detected. Avian pox is a viral disease caused by avipoxviruses and commonly produces characteristic skin lesions. The estimated lifetime prevalence of visible pox was 8.3%.

Researchers analysed 1,549 captures of 588 dunnocks from a rural site on the north-east edge of Exmoor. Annual prevalence ranged from zero to 25.8%. At the same site, no lesions suggestive of avian pox were recorded in more than 41,000 captures involving over 23,000 individual birds from 50 other species.

Mostly first-year infections and a late-summer peak

Most dunnocks that developed skin lesions did so during their first calendar year, and the researchers found no evidence of the disease recurring in the same individuals. They suggest that a single infection may therefore produce long-lasting or lifelong immunity. The disease was also strongly seasonal in most years, generally peaking in late summer.

No evidence of lower apparent survival

Estimated apparent survival was 0.37 for dunnocks with avian pox and 0.32 for birds in which it was not detected, giving no evidence of increased mortality among visibly affected birds. Apparent survival combines true survival with the chance that a bird remains in the study area and is encountered again, so it is not identical to direct mortality.

Avipoxvirus DNA in blood-feeding louse flies

The same avipoxvirus DNA sequence was found in a skin lesion and in four of eight blood-feeding louse flies collected from apparently healthy dunnocks, including in years when no clinical cases were observed. This shows that viral genetic material was present in the flies, but DNA detection alone does not demonstrate that the flies transmitted the virus. The authors conclude that avipoxvirus may circulate more widely than visible lesions alone indicate, while the disease observed in this population appeared to have relatively minor effects on bird health.

Sources and image credit

  1. Wawman, D. C., Fiddaman, S. R., Lawson, B., Christodoulou, M. D., Sheldon, B. C., & Smith, A. L. (2026). A longitudinal study of avian pox in a small passerine, the Dunnock Prunella modularis.Primary peer-reviewed accepted article deposited publicly on 3 September 2026. The 15.5-year study involved 1,549 captures of 588 dunnocks. Estimated lifetime prevalence of visible avian pox was 8.3%; affected birds showed no lower apparent survival, disease usually peaked in late summer and no recurrence was seen in the same individuals. No pox-like lesions were recorded in more than 41,000 captures of 50 other bird species at the site.
  2. Wawman, D. (2026). Avian pox in Dunnocks capture data [Dataset].Supporting CC BY capture and disease dataset deposited 2 August 2026. The News Desk story is dated to the 3 September public deposit of the peer-reviewed accepted article because that record first publicly presented the analysed conclusions reported here.

Image: Dunnock (Prunella modularis occidentalis) at Cumnor Hill, Oxford, United Kingdom, 22 January 2023. Photo: Charles J. Sharp / Wikimedia Commons. CC BY-SA 4.0. Representative species image; not a study bird. · CC BY-SA 4.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

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