Non-governmental organizations and experts in Slovakia have been stressing negative impact of thermal insulation of prefabs on populations of birds and bats for several years. One of the most threatened species by these activities is Common Swift. Swifts have adapted to nesting in buildings due to the loss of their natural nesting habitats (e.g. hollow trees, rocks). Recently almost 100% of the population of Common Swift in Slovakia is nesting in buildings in cities and especially prefabs provide suitable nesting sites not-easily accessible by predators. Thermal insulation of prefabs has become an intensive and popular technology in Slovakia, particularly concerning old houses built back in 1960s and 1970s. Unfortunately this technology is applies especially during the most sensitive reproduction period of Swifts. In several cities it has led to a rapid decreasing of populations of Swifts or even to their complete disappearance from the cities.
Swifts’ nests can be found usually in ventilation holes or crevices between panels on prefabricated houses. In the same places and also in small hollow spaces under roofs colonies of bats can be found as well. Thermal insulation and reconstruction works often result in destruction of these nesting and roosting sites and trapping and killing of birds and bats inside buildings. The most critical period of the year is between April and August when the Swifts are taking care of their eggs, hatchlings and young birds. Swifts are strongly bound to their nesting sites. If these are destroyed for the birds it is a problem to find a new suitable nesting site.
It needs to be understood that Swifts and bats do have their role in urban ecosystems and are important for keeping ecological balance. They feed mainly on mosquitoes; one Swift can catch 50 grams of mosquitoes and one bat can catch over 3000 mosquitoes just during a one night.
Common Swift and all bat species occurring in Slovakia are listed as protected. Economic value of one individual of Swift is 165 EUR, economic value of one individual of bat varies between 165 EUR and 330 EUR, depending on the species. By entering the European Union Slovakia has committed itself to ensure appropriate protection of all species of the European importance, including birds and bats. If this commitment is not fulfilled there is a risk of high financial penalties to be paid by Slovakia to the European Union. If this happens it will be all of us to contribute via taxes.