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Kidney Oxalate Deposits Found in a Quarter of Icelandic Rock Ptarmigan Examined

Female rock ptarmigan in summer plumage on gravel at Botnsvatn, Iceland.
Research · Disease, parasites & microbiology

A 13-year survey of wild rock ptarmigan (Lagopus muta) in northeastern Iceland found two recurring conditions: oxalate crystal deposits in the kidney tubules and mange caused by skin mites. The pathology study used birds collected between 2006 and 2018 as part of long-term monitoring of health and population changes.

Kidney tissue from 1,263 birds was examined histologically, and oxalate crystals were found in 319, a prevalence of 25.3%. Prevalence did not differ significantly between age or sex groups, although juveniles had higher average severity scores than adults. The authors suggest that the birds most likely acquired oxalate through their diet. It remains unclear whether the deposits affected kidney function or overall health.

Mange was another common condition

Mange was recorded in 203 of 1,108 birds examined for skin lesions, a prevalence of 18.3%. It was associated with skin-mite infestation and was more common in juveniles than adults. Among adults, females had a higher prevalence than males, whereas juvenile males and females had similar prevalence.

Coccidia were detected in faecal material and intestinal tissue, but caused negligible histopathological damage to the intestinal lining in the examined samples. Previous traumatic lesions were found in 2.6% of 1,294 dissected birds, most often affecting the sternum and pectoral muscles. The authors considered collisions with human-made structures such as fences the most likely explanation for many of these injuries.

Sources and image credit

  1. Sigurðardóttir, Ó. G., Skírnisson, K., & Nielsen, Ó. K. (2026). Long-term pathological survey of Icelandic rock ptarmigan (Lagopus muta): Renal, dermatological, and traumatic lesions. Icelandic Agricultural and Environmental Sciences, 39, 23–41. https://doi.org/10.16886/IAS.2026.02Long-term pathological survey of wild rock ptarmigan collected in northeastern Iceland in 2006–2018.

Image: Charles J. Sharp / Wikimedia Commons. Wild female rock ptarmigan at Botnsvatn near Húsavík, northeastern Iceland, 10 August 2025. Representative species photograph, not a bird from the 2006–2018 study. Cropped to 16:9. · CC BY-SA 4.0 · Source

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