Natural History Sciences. Atti Soc. it. Sci. nat. Museo civ. Stor. nat. Milano, 9 (2): 27-34, 2022 DOI: 10.4081/nhs.2022.594 The western European hedgehog Erinaceus europaeus L. 1758 on San Pietro Island (southern Sardinia, Italy) and an updated review of its presence on the Italian small islands Corrado Battisti ‘Torre Flavia’ LTER (Long Term Ecological Research) Station, Protected Area Service, Città Metropolitana di Roma, Via G. Ribotta 41, 00144 Roma, Italia. E-mail: c.battisti@cittametropolitanaroma.it © 2022 Corrado Battisti Received for publication: 15 November 2021 Accepted for publication: 8 March 2022 Online publication: 20 October 2022 Abstract - The current presence and local distribution of the western European hedgehog Erinaceus europaeus L. 1758, on San Pietro Island (Southern Sardinia, Italy) are here discussed for the period 2013-2021 with a short review of the species’ occurrence on the small Italian islands. The species was found in the central-east- ern sector of the island, which is characterised by a high urban and infrastructural density and an agricultural mosaic, both suitable eco- logical conditions favouring its presence. Most of the direct data were obtained from road kills. Despite the elusive behaviour of the species and the consequent possible underestimation, it can be assumed that the species shows a low density. In this respect, it might be interest- ing to investigate whether local limiting factors, either anthropogenic or natural might act on the hedgehog population. At a larger scale, the updated review of the small Italian islands shows the presence of the species on 13 islands, of which probably only Elba, Asinara and San Pietro (all >50 km 2 ) support established populations. Further research is needed to study anthropogenic origin, history of introduc- tion, genetics, density, and medium-long-term viability of these small populations in each insular context. Key words: eradication, introduction, road kills, small island, viability. Riassunto - Il riccio europeo occidentale Erinaceus europaeus L. 1758, sull’isola di San Pietro (Sardegna meridionale, Italia): distri- buzione locale e revisione aggiornata della sua presenza nelle piccole isole italiane. Una indagine sulla presenza del Riccio europeo occidentale su un’isola circumsarda (San Pietro), condotta dal 2013 al 2021, ha evi- denziato una distribuzione limitata al settore centro-orientale, carat- terizzato sia da una più alta densità urbana e infrastrutturale, sia dalla presenza di mosaici agricoli, condizioni ecologiche sinantropiche che possono favorire la presenza di questa specie. La maggior parte dei dati originali è stata ottenuta da investimenti con autoveicoli. Benché la specie mostri un comportamento elusivo e i dati potrebbero essere sottostimati, si può ipotizzare una bassa densità di popolazione sull’isola. A tal proposito, potrebbe essere interessante verifcare se ciò possa essere fatto risalire a fattori locali limitanti, sia antropici sia naturali. Su scala nazionale, la revisione della letteratura evidenzia la presenza su 13 piccole isole italiane, con presenza di popolazioni stabili probabilmente solo su Elba, Asinara e San Pietro (tutte con superfcie > 50 km 2 ). Ulteriori ricerche sono necessarie per studiare l’origine, la storia dell’introduzione, la genetica, la densità e la vita- lità a medio-lungo termine di queste popolazioni in ciascun contesto insulare. Parole chiave: eradicazione, introduzione, piccole isole, road kill, vitalità. INTRODUCTION The western European hedgehog Erinaceus europa- eus L. 1758 (Mammalia: Erinaceomorpha) is a common generalist species, widely distributed in mainland Italy, in Sicily, in Sardinia and in some small islands (Amo- ri, 1993; Angelici et al., 2009; Reggiani & Filippucci, 2008; Loy et al., 2019; Tab. 1). In Sardinia, this mammal has been introduced in the middle and late neolithic (4 th Millennium B.C.; Cetti, 1774; Cei, 1941; Sanges & Al- cover, 1980; Vigne 1992; Masseti, 1993; Wilkens, 2003; Baldino et al., 2008). However, although the hedgehog has been studied in Sardinia (e.g., roadkills: De Montis et al., 2017; parasites: Scala & Garippa, 1996, Poglayen et al. 2003; Fois et al., 2006; see also Regione Sarde- gna, 2017), data on its presence and local distribution on the circum-Sardinian islands, where this insectivore has been introduced, are still lacking (Angelici et al., 2009; Masseti, 2019). In this paper, I reported some direct and indirect re- cords of presence and data on the local distribution of the western European hedgehog on the Island of San Pietro, a circum-Sardinian medium-sized island (Sulcis archipe- lago). The western European hedgehog has also been re- corded on several other small islands along peninsular Italy and on neighbouring large islands (Sicily and Sar- dinia: e.g. Angelici et al., 2009). In this regard, given the interest in the presence and introduction history of this erinaceomorph in these contexts, I carried out an up-to-date review of scientifc and grey literature on its presence on Italian small islands, also providing preli- minary considerations on its status (occurrences of only occasionally introduced individuals vs. hypothetical sta- ble populations).