NatureScot and the UK Centre for Ecology & Hydrology (UKCEH) completed a count of burrows on the Isle of May National Nature Reserve (NNR) in the Firth of Forth, a protected and internationally important habitat for seabirds.
Based on the all-island count earlier this summer, scientists estimate there were 36,500 occupied puffin burrows, compared to 52,000 in the last survey in 2024, and 39,000 in 2017.
NatureScot Isle of May Reserve Manager David Steel said: “This decline is disappointing and concerning. Puffin numbers on the island fell sharply in the 2000s and recovered in the 2010s but have now dropped again.
“The decrease appears to be linked to a combination of ongoing pressures on seabird food supplies, poor winter survival and increasingly extreme weather conditions. Unfortunately, this mirrors similar challenges that are affecting seabirds more widely.
“All of this underlines the importance of continued monitoring and conservation work at sites like the Isle of May NNR, where data and research are playing a vital role in helping us to understand these trends and respond.”
Puffins can spend up to eight months of the year out at sea, only returning to land to breed in early spring. They generally mate for life, and pairs often return to the same nesting spot each year where the female lays a single egg.
UKCEH has been monitoring seabird colonies on the Isle of May for 50 years, and its long-term research has shown that species have struggled with the impacts of climate change.
Rising ocean temperatures can reduce the availability of puffins’ food sources, particularly sandeels, which affects their survival rates and ability to produce offspring. In addition, periods of heavy storms in recent years have killed large numbers of birds.
Mark Newell, UKCEH’s field manager on the Isle of May, said: “We believe that the puffin population has recently suffered from a series of extreme climate events, including marine heat waves and intense storms affecting survival in three of the last five winters.
“The concern for puffins and other seabirds is that climate scientists are predicting an increase in the frequency and severity of extreme events in future.”
Field workers at UKCEH and NatureScot carried out the count by sweeping back and forth across the whole island for six days, counting each hole in the ground and assessing whether it is excavated by a puffin or rabbit. A sample of plots are then checked carefully to determine whether they are currently occupied by puffins, and this correction factor is applied to the whole island count. Although the number of burrows was similar in 2026 and 2024, the occupancy rate was significantly lower this year.
This year the Isle of May celebrated 70 years as a National Nature Reserve (NNR). NatureScot manages 29 NNRs, covering 41,300 hectares or 0.54 percent of Scotland’s land. These are special places where everyone can enjoy the very best of Scotland’s nature. They help protect an amazing range of wildlife and landscapes, including many rare species and habitats of international importance.
Supporting species recovery is a key part of NatureScot’s ambitious plan for nature recovery in Scotland over the next four years and work on our NNRs is leading the way, making a direct and significant contribution to the Scottish Biodiversity Strategy’s ambitious target to halt biodiversity loss and restore nature by 2045.
