Light pollution and bat conservation

Light pollution is the presence of anthropogenic and artificial light in the night environment. Light pollution threatens the natural balance in protected areas, disturbs scientific and amateur astronomical activity, and at the same time consumes a lot of electricity. In addition to having very adverse effects on nocturnal animals, light pollution is also adversely to human health. Light pollution is thus the result of inappropriate and excessive use of lights. Within the Gorička krajina project, some activities were dedicated to reduce light pollution, replacing unsuitable lighting on nine buildings.

Influence of artificial light and light pollution on bats
The researchers found that bats whose shelters are illuminated leave roosts later than they would otherwise - at dusk. Most of these lights start to illuminate at dusk, and because of the outside light, the bats dont know that its actually dark outside. Only when the bats become really hungry do individual bats start to fly out to hunt. Unfortunately, most often this happens several hours after dusk and therefore bats miss the peak of insect activity. This, of course, negatively affects the nutrition of bats and their young. The effect of artificial lighting on bats is also indirect. Lamps reduce the abundance and diversity of insects, which are the most important prey of bats.
Therefore, it is best not to use artificial light sources at all or to use them as little as possible, where it is really needed and only when it is needed. Let’s consider whether public lighting is really needed everywhere. Lets enjoy the darkness and the starry sky!

Bat conservation
The main reason for the bat numbers decline is the loss of suitable habitats, which includes the loss of roosts and shelters along with the loss of foraging habitats. Traffic and windmills also threaten bats. For long-term bat conservation along with  following measures should be implemented.
1. Protection of bat roosts
The most important conservation measure is the preservation of bat roosts. When renovating buildings, we preserve structures such as wooden paneling on the walls and openings in the attic. Another important measure is retaining access points for the bats. Renovations of buildings should be carried out at a particular time of year when bats are not present in the buildings.
2. Conservation of landscape features like hedges and ponds.
Hedges and other line structures, such as tree-lined lane, stone fences or dry stonewalls, are important for orientation of bats within the landscape. Because foraging at night, bats prefer to fly along hedges or forest edges rather than across open landscapes, as they are less exposed to predators.
Bats often hunt insects near water bodies - puddles, ponds and lakes. Insects live in high densities near water. Water bodies is especially important foraging habitats during rainy weather.
3. Install a bat-box
Bat boxes are artificial roosts placed into areas where suitable structures lack. Bats boxes can be made of wood or concrete and are most often used as summer roosts. Bat boxes should be installed on suitable spot and high enough to prevent access of predators.
4. Sufficient amount of deadwood in woodlands
Standing and fallen old, decaying or dead wood have several roles in the lives of bats. The dead wood is inhabited by a variety of insects and other animals that bats feed on. Standing trees with cavities or crevices and peeling bark enable bats to find roosts under the bark or within the cavities. Some bat species are specialized tree-dwelling bats who live only in old and deadwood-rich forests.