Bats are flying mammals and they can fly a long way to reach their hibernacula or their breeding sites. Some species commute regularly from the Baltic regions (Latvia, Lithuania, Estonia and Finland) to northern Spain or Italy, thus moving for hundreds of kilometers each year.
The bat yearly cycle turns around the availability of preys, that is arthropods like mosquitos, moths and spiders. While some bat species survive the lack of food (winter) by hibernating in caves and mines with proper temperature and humidity conditions, others migrate to warmer areas where they can keep on hunting their favourite preys.
Bats can easily navigate in the dark thanks to their biosonar, that is by emitting ultrasounds from their mouth or from their nostrils. The soundwaves hit against preys and obstacles and bounce back into the bats ears giving vital information such as the precise position of the objects in space, what they are made of, their speed and direction of movement with respect to the bat, the presence of preys and if and how (direction and speed) they are moving.
Bats are taxonomically divided in two suborders: Microchiroptera and Megachiroptera. The former includes about 180 species distributed in the Old world, comprising large bats who feed exclusively on fruit, nectar and pollen. Microchiropteran bats instead are small or medium sized and count approximately 900 species widespread at all latitudes with maximum levels of species richness in the tropics.
From the ancestral insectivorous diet, which characterizes 99% of all European bat species protected by the Eurobats, bats evolved several kinds of diets: in the tropics you can find carnivore bats, fruit eating, nectar eating or pollen easting bats and also sanguivorous bats.
Only one species listed in the Eurobats Annex is a Megabat and therefore does not echolocate and is strictly herbivorous, feeding on the fruit, nectar and pollen of about twenty different tropical plants.
It's strikingly evident how important bats are for the balance of countless ecosystems both as limitant factors to arthropode populations and as pollinators and seed dispersers, playing a part in maintaining forests and economically important plants such banana trees, agave, fig trees, etc.
All European bat species are threatened to some extent. In some countries they even underwent local extinctions due to the loss of roosting and foraging sites, the increased use of chemicals in agriculture and the building sector, poisoning bats' preys and roosts, and intolerance and prejudice originated by misknowledge of bat biology and habits.
Some hyperdiseases had a crucial role in determining the decline of some populations; recently in the USA an alarming disease (White Nose Sindrome) is treatening thousands of bats.