"Two of them slept peacefully here, one was over here separately, another one was over in that corner and then the fifth was here above the door," Rõuge resident Endel Kroon told ETV news broadcast "Aktuaalne kaamera," pointing to the exact spots where bats had hibernated in his now-batless cellar.

While bats have indeed already left their winter hibernacula, over the winter Kroon saw his guests quite a bit.

"Depends on when I stop in my cellar – if during the morning, I bid them good day; if in the evening, I bid them good night," he explained. "I give them a close look and I'd love to pet them, but I don't dare, because I might wake them up – although I'd love to pet them."

Bats carry a special meaning for Kroon as well. A singer in the Vanemuine Opera Choir for 39 years, including having sung in Johann Strauss' famous operetta "Die Fledermaus" – literally "The Bat" in German – his sleeping cellar guests conjure up other memories too.

"Of course, absolutely and very often," he acknowledged. "Then I pull out my photo album, look at the photos and reminisce about this lovely period [in my life]."

While Kroon's cellar is a model example, according to the Estonian Theriological Society's (ETS) information, fewer and fewer suitable sites remain for bats to overwinter in.

"Right now, a lot of root cellars are crumbling because they're no longer needed, and for bats, likely the first thing that will disturb them is if a door comes off its hinges or a door rots away," ETS chair Oliver Kalda explained. "The cellar will get cold, and it won't suit them anymore."

To that end, Kalda said that in terms of bat hibernacula, a help would be restoring old cellar doors.

The summer ahead is a concern as well, however, when bat colonies may nest under building roofs or behind clapboard siding. Starting repair or renovation work on a building housing a bat colony could kill the entire colony, impacting the broader bat population as well.

"If you want to insulate a house, for example, removing the siding, then, of course, you can insulate in summer too, but that siding should ideally be removed now already so that that [bat] colony can't gather there, thus preventing that direct contact," Kalda said.

Estonia is home to approximately a dozen species of bats, some half of whom winter over on-site. All bat species are protected category II species in Estonia.

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