Stora Karlsö is a beautiful island on the western coast of Sweden: the second oldest nature reserve in the world. Many years ago it was full of ruthless hunters and some precious seabird species were about to extinct when a private company called Karlsö Jagt- och Djurskyddsförenings AB purchased the island in
1880. As soon as that, hunting was banned within the island and long-term plans were made to protect the birds and to increase them in number. It took almost a century to restore the seabirds population since 1880. Rich birdlife and flora have gained their own tourist attraction, as to date, being the most visited and the largest seabird colony in the Baltic Sea.
Stora Karlsö is as small as 2.5 square kilometers. It is lined with ledges of limestone and its vertical cliffs provide ideal breeding places for the seabirds. Tourists visit the island to have a good time watching the well diversified seabird population composed of common murre, great cormorant, guillemot, barred warbler, rosefinch, visiting eagles and many more.
A recent Swedish research conducted on certain bird populations of the island reveals some extraordinary facts about the entwined association between the seabirds and tourists which was not identified till the anthropause during the pandemic of Covid-19. With the evidence of this study, an old question-”what makes the eagles stay away from seabirds?”, is now answered.
Until before the Covid-19 pandemic, the number of sea eagles that visited the island including the seabird breeding season was considerably low. But the number of eagles visiting the island markedly increased during the pandemic and caused a wreak in the island, largely dropping the common murres population.
Tourist visits were dropped by 92% compared to the past three years and conversely, the number of eagles that visited the island increased by 760% compared to the past ten years. Large number of eagles caused massive flushes of seabirds and they were attacked around the breeding cliffs and waters. Even though no murres were caught by the eagles, it caused substantial behavioural changes in murres that they were unable to provide the protection for the eggs in the same way they used to. They tend to leave the eggs unattended which eventually were predated by gulls and crows or were fallen down from the ledges. Collectively this resulted in 26% less breeding performance compared to the past ten years.
According to this study, Eagles’ activities were unexpectedly increased due to the lack of human activities on the island. Earlier some protection has been unintentionally provided for the murres by the tourists. Sudden absence of the tourists has provided more freedom to eagles that they could visit the island with no limitation. However, according to the research team, only future studies will confirm whether this effect will be reversed upon tourist visits or whether the anthropause has caused a permanent effect on seabirds.
This is a worthy example with proof that how the role of humans in ecosystems is sometimes beneficial. This study will open the doors for the new dimensions of social-ecological concepts in conservation programs in the future.