Concern is being voiced about the internationally-important puffin colonies in the Western Isles following a spate of bird deaths in the Canary Islands.
Puffins are critically endangered, and the mysterious deaths in the Canaries and parts of the Spanish mainland are sounding alarm bells in the UK as it is reported that four dead birds had been ringed in Scotland.
Three had leg rings indicating they were part of the Sule Skerry puffin colony in Orkney, while the other was ringed in Garbh Eilean in the Shiants.
Ornithologists are now calling for further research as it is feared that puffins, who primarily eat sand eels, face multiple environmental threats, including climate and oceanographic change.
It is thought the deaths in Spain, which is outwith the puffins' normal wintering zones, are likely associated with recent bad weather and dwindling food supplies.
The Outer Hebrides are a major puffin breeding ground.
The birds spend most of their time at sea, only coming ashore to breeding grounds in March and April.
It is estimated that around 60,000 pairs were breeding on the Shiants as of 2018.
Last year, there was concern about seabird populations in the Isles during the avian flu outbreak.