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The Stag Beetle Monitoring Project

La Mandria Regional Park (Turin), Italy

With the beginning of the activities in the “Ciabot Degli Animali,” we have increased our presence in the Park of La Mandria, offering photo workshops for adults and children on the weekends. These activities allow us to finance a new project focused on the conservation of nature.

Skua Nature, together with “Ente Parchi Regione Piemonte,” the organization responsible for the management of the Park of La Mandria, and the University of Pavia, has launched a project to monitor the stag beetle (Lucanus cervus) to know how this sensitive species is doing in the Park.


The stag beetle is an insect of the family Lucanidae, which belongs to the order Coleoptera. With its considerable dimensions (the male reaches a length of 10 cm, including the large mandibles), it is the largest Coleoptera in Europe. It lives in the cavities of tree trunks, with a particular preference for oaks.

In males, there are different shapes and sizes of mandibles. Those with the smaller appendages are called PRIONODONT, the middle ones MESODONT, and the larger ones TELODONT.

Many factors contribute to the size of the adult, such as the type of wood the larva feeds on during its development, the amount of food available, and the seasonal conditions during the developmental stages. It can take up to 5 years for the larva to pupate before it reaches maturity which will last only a few months, the time necessary to reproduce.


The rare TELODONT males, whose mandibles are out of proportion with the rest of the body, have difficulties moving and performing stable flights. These organisms consist almost entirely of insects, a large proportion of which belong to the order Coleoptera. Their peculiarity is that they feed on dead wood, thus promoting plant decomposition. These insects play a fundamental role in the ecological cycle that regulates the forest system and its renewal.

In the case of Lucanus cervus, rotting wood gets digested by symbiotic bacteria that reside in the larval digestive tract. . The undigested material returns to the environment and promotes the growth and development of generations of plants and trees in the understory, ensuring the proper functioning of the forest ecosystem. This is important because a healthy understory is fundamental for the preservation of the surrounding environment and can fight phenomena such as desertification or hydrogeological instability (a widespread problem in Italy with significant socio-economic implications).

The TELODONTI male, very scarce, having jaws disproportionate to the rest of the body, presents difficulties in movement and when performing stable flights.


This stag beetle plays a fundamental role in the food chain, not only in terms of carbon sequestration in the soil but also because it is the main staple of many animal species such as Picidae and Mustelidae that feed on both larvae and adults.

Since the stag beetle is a link between the different ecological cycles, it is imperative to protect the species in order to secure the whole chain. For these reasons, the species is protected and included in the Habitats Directive as it is threatened by the fragmentation of its ecosystem, which consists mainly of old deciduous forests, especially oak forests.

Furthermore, red oak (an allochthonous plant often used for reforestation in the past) is not beneficial to the species and appears to deplete the soil and alter its composition.


This saproxylic insect (about a third of the animal biodiversity in forests, half if we consider only beetles) is associated with the presence of necromass, so it is essential to maintain a certain amount of decayed wood in parks or forest areas. There are even guidelines for the minimum amount a forest must have to be considered healthy. Understory clearing and maintenance policies, especially in the past, have often resulted in impoverished and unsuitable habitats for various species, including Lucanus cervus. The species also serves as a bioindicator of the health of the areas in which it lives.

The species is protected and listed in the Habitats Directive because threatened by the fragmentation of its ecosystem, which consists mainly of old deciduous forests, particularly oak woodland.


Monitoring will be performed through direct observation of the species in the area by a team of Skua Nature Group, La Mandria Park rangers, and volunteers.

To estimate the population size, an expert from the University of Pavia studied the Park of La Mandria and identified the areas of most interest for the stag beetle In these areas, five sample trails (called transects) of 500 meters were delineated, which will be studied by the staff in search of Lucanus cervus specimens.

The activity will be carried out by well-trained observer who will walk from 15 minutes before and 15 minutes after the exact time of sunset, for five weeks, between the middle of June and the end of July. During this period, the reproduction of the species takes place, and the males fly in search of a female.

The length of the transect is divided into five 100-m sections marked with red and white sampling lines. The frame is used to facilitate accurate data collection and to record field data on datasheets. Specific coding will be adopted for each sighting to distinguish males, females, and individuals with unidentifiable sex.
The observer will also record temperature and humidity parameters at the beginning and end of monitoring to provide a history of observations useful for future studies.

At the end of the five weeks, we will be able to estimate the size of the population in the Park, information that is not currently available. We will obtain data on the status of the stag beetle and, over time, its population trend. We will also gain a better understanding of the condition of the forests and act consistently to improve their state and promote the future conservation of Lucanus cervus and the Park itself.