Following the avian flu outbreak last year, NatureScot has warned that some seabird species have returned to Scotland in noticeably lower numbers.
The nature agency reported that great skuas in Shetland seemed to have been particularly hard hit.
Up to 90% of the material may have been lost at one site, Hermaness.
Additionally, there are issues with terns all over Scotland, including at NatureScot's Isle of May and Noss National Nature Reserves.
Last year, hundreds of dead birds, including great skuas, also known as Bonxie locally, were discovered in Shetland.
The great skua population is still being counted, but NatureScot reported that preliminary findings from some of the key Shetland sites indicated "significant breeding population declines.".
It stated that Scotland supported 60% of the great skua breeding population worldwide.
Because of this, ringing and research activities have been temporarily suspended for great skua in order to reduce unwarranted stress on the populations.
NatureScot reported that although tern nesting had been delayed on Noss in Shetland, some eggs had now been laid.
The nature agency reported that this year's nesting had not yet taken place on the Isle of May, while on Rum, the terns had left without laying any eggs.
In an effort to better understand the extent of the impact, targeted surveys of seabird breeding populations are still being conducted.
Despite recent virus outbreaks in England, colonies in Scotland have so far managed to avoid the high number of fatalities seen last summer.
The impact of the terrible losses from the previous year hasn't yet been fully assessed, according to NatureScot wildlife manager Alastair MacGugan, but we are keeping a very close eye on the low numbers of great skua and terns returning to our shores.
The good news is that, at least in Scotland, we are not seeing as many dead birds around breeding sites as we did the previous year.
It's possible that the remaining birds have developed some level of virus immunity as a result. If so, there is reason for hope because populations may start to gradually replace the losses that happened last year.
But the outbreak is far from over, so we're not letting our guard down. ".
According to public health recommendations, the virus poses a very low risk to human health.
