“The owls only breed if there is an abundance of food around, and we haven't had such a good lemming-year in ages,” said Thomas Bergström of the Jämtland County Council to The Local.
So called “lemming–years” traditionally occur every 3-4 years, according to Birger Hörnfeldt, of the department of wildlife, fish and environmental studies at the Swedish University of Agricultural Sciences in Umeå.
The last three decades however have seen such unfavourable weather that the number of lemmings had diminished considerably.
If winters are too clement, the little rodents are forced up from under the snow-clad ground too soon and perish.
But the last two winters have been cold enough for lemmings to stay under their blanket of snow and subsequently the stock has grown, according to Hörnfeldt.
Following the heat wave in April, the lemmings were forced out of their holes to fall prey to the vigilant birds, becoming a veritable feast for hungry predators.
And the abundance of lemmings in the north of Sweden has benefited the snowy owls of Jämtland, where five little chicks hatched in the beginning of June.
It is estimated that the owls have bred in Sweden a handful of times since the 1980's, with the latest known brood hatching in the county of Jämtland 60 years ago.
The snowy owl is an endangered species. In the Nordic countries scientists believe there may be as few as ten breeding pairs, while there's believed to be approximately 1,000 owls in North America.
Research shows that the nomadic owls migrate freely in the area between Scandinavia and Siberia in order to find food. During the winter they can be seen far down in southern Sweden.
“It is actually impossible to estimate exactly how many snowy owls exist in Sweden today because they move around so much,” Bergström said.
The county council are relying on the public, in the form of birdwatchers and interest groups, to provide them with information regarding the owls.
“It is only when someone discovers and reports to us that we know for sure that they have bred,” Bergström explained to The Local.