Credit: Eurac Research | Valentin Heimer

PHOTOSTORY

Bat by bat

PHOTOSTORY

Mist nets are a common tool used to study bats in their natural environment. These nets are made of very fine, almost invisible threads, stretched between poles in places where bats are likely to fly, such as near bodies of water such as Lake Caldaro/Kaltern. The nets are typically set up at dusk or after dark, which is when bats are most active, and researchers check the nets frequently to make sure the bats do not become stressed or trapped for too long. Overall, mist nets provide a valuable way for scientists to learn more about bat populations, behavior, and health, helping inform conservation efforts.

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Credit: Eurac Research | Andrea De Giovanni

PHOTOSTORY

Once a bat has been gently removed from the mist nets. Certain steps are taken to identify which species it is. Measuring the forearm length, the distance from the elbow to the wrist is one of the most important and standard measurements because it helps distinguish species. In this case we have Bechstein’s bat, Myotis bechsteinii. Measurements are taken in millimeters using calipers or a ruler and are essential for identifying species, studying growth, and comparing individuals across populations.

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Credit: Eurac Research | Valentin Heimer

PHOTOSTORY

To weigh a bat in the field, researchers use a spring or a digital hanging scale that measures in grams. First, the bat is gently placed into a soft, breathable cloth bag. The bag is then hung from the scale's hook or attachment point. Researchers first weigh the empty bag to get its tare weight, then weigh the bat inside the bag, and subtract the bag's weight to get the bat’s actual weight. This method is quick, safe, and minimizes stress on the bat, allowing for accurate weight measurement without direct handling during weighing.

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Credit: Eurac Research | Andrea De Giovanni

PHOTOSTORY

A loupe is used in bat monitoring to magnify features difficult to see with the naked eye, helping researchers accurately identify species and assess health. It allows close inspection of fine details like dental patterns, skin texture, fur characteristics, and wing structures. Loupes are also useful for spotting parasites, wounds, or other subtle signs of illness.

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Credit: Eurac Research | Andrea De Giovanni

PHOTOSTORY

A bat’s wings offer valuable clues to both what species it is and how it lives. Wing shape and size vary between species, reflecting how they fly and where they live. Bats with long, narrow wings are built for fast flight in open areas, while those with shorter, broader wings are better suited for slow, agile flight in cluttered environments like forests. Features such as forearm length, membrane color, bone structure, and whether the wing is furred also help researchers identify species in the field. This is Myotis myotis, the Greater mouse-eared bat. This species has short, wide wings that allow it to fly slowly but turn easily. It usually flies close to the treetops while hunting and has strong, durable wings.

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Credit: Eurac Research | Valentin Heimer

PHOTOSTORY

After the data is collected, the bats are released back into the wild, usually at the same spot where they were caught.

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Credit: Eurac Research | Andrea De Giovanni

PHOTOSTORY

This is Hypsugo savvii, or Savvi’s bat a vesper bat. A vesper bat is a small to medium-sized bat from the Vespertilionidae family, the largest group of bats worldwide. They lack a nose leaf, use echolocation to hunt insects, and are active mainly at dusk. Their name comes from vesper, meaning “evening” in Latin.

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Credit: Eurac Research | Andrea De Giovanni

PHOTOSTORY

Barbastella barbastellus or the western barbastelle bat is a medium-sized bat with a distinctive pug-like nose and broad, joined ears covered in ginger-brown fur on the back. Its triangular tragus – the small, pointed flap inside a bat’s ear that helps with echolocation – tapers to a point midway along its length. It measures 40–55 mm in head-body length, with a wingspan of 26–29 cm, a forearm length of 35–45 mm, and weighs 6–13 g.

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Credit: Eurac Research | Valentin Heimer

PHOTOSTORY

A Bechstein bat being released from a cloth bag after having been weighed. Bats are weighed to assess their health, growth, and condition. Weight helps researchers monitor nutrition, detect illness and compare populations. The Bechstein bat’s scientific name is Myotis bechsteinii and it is found almost exclusively in woodlands. The destruction of ancient, mature forests, coupled with intensive woodland management practices, has led to a decline in its numbers.

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Credit: Eurac Research | Valentin Heimer

PHOTOSTORY

Researcher at the Institute for Alpine Environment Hanna Steigleder in a WW2 bunker. These bunkers built in the foothills south of Bolzano provide precious refuge for the nocturnal creatures. In places like bunkers, bats are monitored using several methods other than mist nets. Acoustic monitoring with ultrasonic detectors records bat echolocation calls to identify species. Researchers also conduct roost surveys by inspecting bunkers for bats and signs of their presence.

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Credit: Eurac Research | Andrea De Giovanni

PHOTOSTORY

Eva Ladurner, from the Museum of Nature South Tyrol and Hanna emerging from a bunker. Bunkers are important for bats because they provide safe, stable environments for roosting and hibernation called hibernacula, especially where natural shelters are lacking. Their cool, damp, and dark interiors offer the consistent temperature and humidity bats need to survive the winter. Bunkers are also well-protected from predators and human disturbance, making them ideal refuges. In many parts of Europe, old military bunkers are even preserved or adapted specifically to support bat conservation.

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Credit: Eurac Research | Andrea De Giovanni

Bat by bat

30 October 2025

de en it

As dusk falls over South Tyrol’s protected habitats, researchers set out on a field trip to monitor and classify local bat species. Equipped with mist nets and detectors, they quietly track these nocturnal creatures, gathering vital data on their populations and behaviors. This work not only helps protect bats – key indicators of ecosystem health but also the fragile environments they rely on.

As part of the EU’s Natura 2000 Habitat Directive, a new report on South Tyrol, supported by Eurac Research, evaluates 45 habitats and 91 species. Bats feature as a keystone species. The report will be published in the upcoming year

For the areas in South Tyrol, Eurac Research worked alongside the Nature Museum of South Tyrol and the Office of Nature of the Province. Among the report’s most detailed findings is the focus on bats. Bats are often overlooked but vital indicators of ecosystem health. South Tyrol is home to 26 bat species, and for the first time since 2000, the lesser horseshoe bat shows encouraging signs of recovery. These species, which often roost in churches and private homes, are benefiting from more careful monitoring, protection and public awareness. But not all trends are positive. Other species, like the whiskered bat and the greater horseshoe bat, continue to decline. Experts suggest that intensive agriculture and the loss of the bat’s natural foraging grounds may be to blame. The report highlights the urgent need for more research to fill knowledge gaps, especially around habitat use and population dynamics.

Natura 2000: keystone species

A keystone species is a one that has a large impact on its ecosystem. Even if there are not many of them, the presence of a keystone species is crucial for maintaining the structure, diversity, and health of the ecosystem. If a keystone species is removed, the ecosystem may change drastically, often leading to a loss of biodiversity or even the collapse of the entire system. Conversely, healthy populations of keystone species often signal a healthy, biodiverse ecosystem. In European nature conservation, protecting specific animal and plant species is key. Certain species with special ecological roles serve as indicators for entire ecosystems. The EU’s Natura 2000 initiative highlights many such species whose conservation status must be regularly monitored by member states and their regions, including South Tyrol. To support this, Eurac Research’s Institute for Alpine Environment, in cooperation with the Office of Nature, and the Museum of Nature, monitors invertebrates and mammals. The project aims to:

Improve methods for assessing conservation status
Survey, map, and monitor species
Provide expert input on conservation projects
Lay the groundwork for updated Red Lists.

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Bat by bat

Natura 2000: keystone species

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