In the villages of the Comprensorio Salto-Cicolano, between the Valle del Salto and the Monti della Duchessa, those who used to go out for snails tell the same story. Once, after rain, they gathered them in quantity along the dry-stone walls of the vineyards and at the edges of the fields. Today in the same places few are found, and in many places none are found any more.
It is a memory, and a memory is not data. It does not say which species, where exactly, in which years, with how much search effort. To become data it must first be fixed, then measured.
Of measurements, in the Comprensorio Salto-Cicolano, there are few. The Società Romana di Scienze Naturali (Roman Society of Natural Sciences) made one hundred and eighteen field trips in the district between May 2021 and November 2024, and above Petrella Salto, at the locality of Fonte delle Vene, it discovered a concentration of species that the authors defined as a biodiversity hotspot. The work came out in 2025 in the Rendiconti Lincei. Scienze Fisiche e Naturali with nineteen signatures, and the present writers are among them. In little more than a tenth of a square kilometre, 505 species of plants, invertebrates and vertebrates were counted.
The molluscs were searched for between December 2023 and July 2024, in ten sessions of four to five hours, turning over stones, lifting branches and logs, sifting the leaf litter. In all, 34 taxa belonging to 22 families were recorded, all terrestrial except the small spring species Bythinella opaca. Seven are Italian endemics. Among them is Helix pomatella, which lives only in a narrow stretch of the Central Apennines and at Fonte delle Vene is fairly common among the rocks and the juniper. There is also Helix straminea, a large snail whose shell can exceed six centimetres; at the site it does not seem common, and it adds to the few stations known for Lazio. The authors judge the state of the molluscs at Fonte delle Vene to be very good.
At first sight the measurement contradicts the memory. In fact it looks at another place. Fonte delle Vene is a damp gorge, with dense woodland, rock faces, two watering troughs and an old spring intake built shortly before or shortly after the Second World War. The steep slopes keep it safe from mowing and the woodland shields it from the heat. The snails of memory lived instead in the vineyards and along the field walls, in a cultivated landscape that, in a land of sharp population decline, has changed. The same study notes the depopulation of Petrella Salto and the neighbouring municipalities.
The cultivated landscape matters, but less simply than it seems. Zuzanna Rosin and colleagues (2017) followed a single snail in the Polish countryside, Cepaea nemoralis, together with its predators, thrushes and mice. Colonies were more frequent where the surroundings held suitable habitat, more uncultivated land and more roads, and human disturbance helped them in two ways, by creating habitat and by taking space from the birds that prey on them. At the scale of a few metres, shelter and moisture mattered. It holds for one species and one country. It does state, however, that the human hand on the landscape can favour snails, and that untilled land is not necessarily a loss.
Then there is the wild boar. ISPRA (Istituto Superiore per la Protezione e la Ricerca Ambientale, Italy’s Institute for Environmental Protection and Research) estimated about one and a half million of them in Italy in 2021, with about three hundred thousand animals culled each year between 2015 and 2021 and one hundred and twenty million euros of damage to agriculture in seven years. The wild boar eats mostly plants, around 90% of its diet according to the review by Sebastián Ballari and Noelia Barrios-García in Mammal Review (2014). To find them it turns over the soil. In the earlier review, in Biological Invasions (2012), the same authors write that rooting reduces plant cover, diversity and regeneration, and that predation and habitat destruction can weigh heavily on animal communities. They also state that almost all studies come from countries where the wild boar was introduced, and few from Europe, where it is native.
In its native range, which includes Europe, the wild boar preys on animals from the most varied taxonomic groups, from invertebrates to birds. According to the same review, animals stay below 10% of stomach contents, but they appear all year round, and for this reason the authors consider them an essential food. Snails are among the prey. In the Ebro Valley, in Spain, Juan Herrero et al. (2006) analysed 137 stomachs of wild boar shot between 1994 and 2004. Snails, among them Otala punctata, made up the main component of the invertebrates eaten, 1.8 per cent of the volume, and were absent in the hot, dry months, from May to August. The same authors conclude that at that site the wild boar is not a significant threat to flora and fauna. Where it arrived with human help, outside Europe, the 2012 review reports instead declines of between 40 and 90% in soil fauna.
For Europe there is a number. In 2021, in Scientific Reports, Derek Risch, Jeremy Ringma and Melissa Price cross-referenced the IUCN Red List with the threats attributed to wild pigs. Worldwide, 672 taxa in 54 countries turn out to be threatened. In Europe the hardest-hit families are the Orchidaceae and the Helicidae (to which Helix pomatella and Helix straminea belong).
In the Comprensorio Salto-Cicolano this link has not been measured. The Lincei study lists as threats to Fonte delle Vene: hunting, grazing, woodland management, intensive mushroom gathering, water abstraction, mountain climbers on the rock faces, summer eco-tourism and the presence of the adjacent SS 578 state road.
In Tuscany, Martina Calosi et al. (2024) followed for two years, from spring 2019 to spring 2021, 126 sample plots on grasslands protected under the Habitats Directive in three protected areas, from the Parco della Maremma to the Riserva dell’Alpe della Luna. They estimated between 3.5 and 22.2 wild boar/km² and found up to 19.2% of the grassland turned over, with peaks in autumn and winter. Rooting increased with animal density, with rain and with nearness to woodland. In their results, the authors call for fencing or targeted culling on the most exposed grasslands.
Beneath the turf, the damage can also be measured in the soil. In the Cilento, in the olive groves of the Monte Licosa site, Pasquale Napoletano et al. (2023) compared rooted and undisturbed soils for one year. In the top fifteen centimetres the rooted soil lost carbon, showed a stressed microbial community and a lower quality index (0.40 against 0.50), with the effect strongest in the cold months.
On fauna, in Italy, the clearest data come from ground nests. In the Maremma, in the province of Grosseto, Senserini and Santilli placed seventy-one artificial nests with pheasant eggs in cereal and hay fields in 2014, some of them inside electric fences the wild boar could not cross. Inside the fences the animal did not take a single nest; outside, it took 66.7% in the zone next to a large wood, where wild boar were numerous, and 19.2% in the one where they were few. In Mediterranean habitats of central Italy, Mori et al. repeated the test in 2020, with quail and hen eggs watched by camera traps. In 47 cases out of 48 the eggs disappeared within a week, and the most frequent predator, ahead of the magpie, the fox and the marten, was the wild boar, in 36% of cases.
For the Murgia in Apulia we have other data. Rocco Labadessa and Leonardo Ancillotto (2023) observed that where wild boar root, more nectar plants grow and more Aristolochia clusii, the food plant of the caterpillars of Zerynthia cassandra, an endemic and threatened butterfly, and that the females choose exactly those sites to lay their eggs. In 2025 two studies, one in a production forest in Sweden and one on the abandoned limestone grasslands of Hainich National Park in Germany, found more plant species in the rooted patches than in the undisturbed ones. The wild boar destroys in one place and renews in another. What counts is how many there are, where they are and what they find.
The research published on 31 July in Nature Ecology & Evolution covers the whole of Europe, and birds and butterflies in particular, not snails. Stanislas Rigal, of the French institute INRAE in Montpellier, and thirty-five other authors, among them Mattia Brambilla of the Università degli Studi di Milano (University of Milan), used counts of 265 bird species and 144 common butterfly species collected between 2000 and 2021 at more than twenty thousand sites in 27 countries, thanks to the work of volunteers in monitoring programmes. They linked species trends to climate, to land use and to the intensity with which land is exploited, then projected everything to 2050 under several scenarios, including those that meet Europe’s conservation targets. The average decline does not stop or reverse in any scenario. With conservation policies the trends improve a little, but birds keep declining, and the hardest hit remain farmland birds. For butterflies the effect is slight. The press release of the European project BioAgora, which co-funded the study, adds that the benefits are greater in western and northern Europe and weaker in southern and eastern Europe, and that grassland butterflies suffer as much from intensive farming as from land abandonment. The authors conclude that current scenarios take a growing demand for natural resources for granted, and that a different framework is needed.
Snails are not in Rigal’s study, but the logic is the same. A model that removes one pressure and leaves the others does not see the curve climb back. In the Comprensorio Salto-Cicolano, the abandonment of fields and the presence and abundance of wild boar may act in synergy; drought, gathering and the “snail killers” used in vegetable gardens are further factors still to be assessed. That is why looking for a single cause is a mistake. Remove one, and the others remain.
Measuring these effects takes work. In the forest of the Parco Nazionale del Circeo (Circeo National Park), 3,200 hectares of lowland woodland enclosed by cultivated fields, Fagiani et al. (2014) compared heavily and lightly rooted areas, counting understorey plants, soil invertebrates, ground beetles and small mammals. They caught more than ten thousand invertebrates, yet almost all the differences remained uncertain, and according to the authors assessing the effect of the wild boar requires many samples and a well-structured research programme before starting.
In the Comprensorio Salto-Cicolano, memory can be turned into data. Testimonies are collected with place, years, species and quantity. The same places are revisited after rain, with the same search time and over the same area. For each point it is noted whether the land is cultivated, pasture, scrub or woodland, and whether it bears the marks of rooting. Rainfall and temperature data are gathered from the nearest weather station, and the one at Santa Lucia di Concerviano has already been used in the study published by the Accademia Nazionale dei Lincei. Memory says where to look; measurement will establish how true it is.
References
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*SRSN (Roman Society of Natural Science)
