White-tailed sea eagles are the largest bird of prey in the UK, and conservationists worry that avian flu has harmed their ability to reproduce.
According to a new analysis, the percentage of eagles raising young in Scotland has decreased from 67 percent in 2021 to 45 percent last year, according to NatureScot.
According to the government agency, it was possible that raptors caught or scavenged on infected birds.
Another sizable raptor, the golden eagle, was reportedly also in pain.
It was discovered that the percentage of golden eagle pairs raising young had decreased from 48 percent in 2021 to 28 percent.
The Western Isles' Lewis and Harris had the largest recorded declines for both eagle species.
According to analysis, the breeding success of white-tailed eagles decreased from 66 percent to 24 percent, and that of golden eagles decreased from 55 percent to 16 percent.
The Scottish Raptor Monitoring Scheme provided the data for the study conducted by the British Trust for Ornithology (BTO).
Seabird populations along Scotland's coast, including gannets on Bass Rock and skuas in Shetland, have been decimated by the avian flu.
In November 2021, the first cases of the flu in birds of prey were found, and by April 2022, a number of different species had tested positive.
The ornithology advisor for NatureScot, John Allan, stated: "Scotland still has healthy eagle populations, but these findings are very alarming.
Compared to last year, we have so far seen fewer positive test results in raptors, but it's still early in the season, so we can't relax just yet.
"We want to see if breeding success starts to increase, so we'll repeat this analysis in 2023. ".
Avian flu can kill both adult and nestling raptors, according to Mark Wilson, acting head of science for BTO Scotland. Laboratory tests for the virus in dead birds of prey have demonstrated this.
