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Acoustic Activity Index Tracked Svalbard Rock Ptarmigan Changes Alongside Manual Surveys

Female Svalbard rock ptarmigan in mottled plumage on open tundra
Research · Other research

Passive sound recordings can track year-to-year and geographic variation in Svalbard rock ptarmigan (Lagopus muta hyperborea) in a way that closely matches conventional field surveys, according to a NINA report published in May 2026. The method was tested as a less field-intensive supplement to the long-running manual monitoring programme on Svalbard.

The index measured male calling activity, not individual birds

Autonomous recorders have been deployed annually since 2017 in four valleys on Svalbard and at two locations in Finnmark. On Svalbard, the units were placed in areas already covered by conventional monitoring and recorded ten minutes of sound every hour during the early breeding season. An automated algorithm then identified the characteristic calls of territorial males.

The researchers built an activity index from male calling during the ten most active days in April. A higher index means more calling activity was detected in the recordings; it does not directly mean that a known number of individual males was present, because the same bird can call repeatedly.

The index followed manual surveys but is not yet a replacement

When compared with population estimates from traditional field surveys, the acoustic index showed strong agreement and captured both year-to-year changes and differences among valleys. The result supports acoustic monitoring as a promising way to follow relative population variation while reducing the amount of fieldwork required during difficult spring conditions.

The researchers nevertheless stress that the method still needs development before it can fully replace manual monitoring on Svalbard. Priorities include optimizing recorder placement and developing algorithms that can distinguish individual birds, which would help convert calling activity into more direct information about numbers of males.

NINA also sees the Svalbard results as a possible route towards systematic rock ptarmigan monitoring on mainland Norway, where there is currently no equivalent national programme. That application remains a future possibility rather than something validated by this Svalbard analysis.

Sources and image credit

  1. Strømeng, M. A., Kleiven, E. F., Ims, R. A., Yoccoz, N., Pedersen, S. T., & Fuglei, E. (2026). Passive acoustic monitoring of Svalbard rock ptarmigan: Validation of an activity-based abundance index. Norwegian Institute for Nature Research (NINA).Primary 2026 NINA report, registered 27 May 2026. Autonomous recorders deployed on Svalbard since 2017 were used to derive an activity-based index from male calls during the ten most active days in April. The index closely matched annual and geographic variation in traditional field-survey estimates.
  2. Norwegian Institute for Nature Research. (2026, June 10). Listening to ptarmigan: sound recordings could transform monitoring in the Arctic.First-hand NINA summary describing deployment since 2017, ten-minute hourly recordings, automated call recognition, agreement with manual counts, and remaining development needs.

Image: Per Harald Olsen (Perhols) / Wikimedia Commons — wild female Svalbard rock ptarmigan, photographed on Svalbard in 2008. Representative image for this story; not presented as an animal or scene from the reported study or event. · CC BY-SA 3.0 · Source

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