Monitoring bats in underground hibernation sites (various parts of Estonia), since 1948 (visual counts of hibernating bats at selected sites, using hand torch).
Monitoring bats on 8 monitoring routes included in Estonia's National Environment Monitoring Programme, since 1994 (detector-based counts of bats on selected routes using line counting and point counting methods). In 2016, four monitoring routes were established at additional sites, thus making these bat counts more powerful.
Detector-based study of bats in Estonia (Estonia), since 1992 (mapping, counting and identifying bat species during spring and summer).
Bats in Towns (Europe), since 1995 (finding, identifying, mapping and counting the flying bats in European towns).
https://bats-in-towns.blogspot.com.ee/p/building-knowledge-based-human-society.html
https://bats-in-towns.blogspot.com.ee/p/building-knowledge-based-human-society.html