Health Status of the Eastern Grey Squirrel (Sciurus carolinensis) Population in Umbria: Results of the LIFE Project ‘U-SAVEREDS’

SIMPLE SUMMARY: Invasive alien species are non-native species introduced deliberately or unintentionally beyond their past or present natural distribution, and their introduction and spread threatens local biological diversity. The Eastern grey squirrel is native to North America and was introduced to the British Islands, Italy, and South Africa. Around the year 2000, a new population of grey squirrels was recorded in Perugia, central Italy, where the species populated an area of approximately 50 km(2), both in woodland and urban areas. The Eastern grey squirrel represents a huge threat to the conservation of the native Eurasian red squirrel when the two species coexist. Moreover, given their confident behaviour with humans, the non-native squirrels can negatively impact public health. The U-SAVEREDS Project was set up for Eurasian red squirrel conservation in Umbria through the eradication of the alien species and it also provided information on the health status of the Eastern grey squirrel to identify any infectious agents. The recovery of zoonotic pathogens allowed to assess the Eastern grey squirrel’s impact on human and domestic and wild animals’ health, provide helpful feedback for the management and eradication procedures, and raise public awareness through environmental education. ABSTRACT: The introduction of the Eastern grey squirrel (Sciurus carolinensis) in Europe is one of the best-known cases of invasive alien species (IAS) colonisation, that poses a severe risk to the conservation of biodiversity. In 2003, it was released in a private wildlife park near the city of Perugia (Italy), where it is replacing the native Eurasian red squirrel (Sciurus vulgaris). The LIFE13 BIO/IT/000204 Project (U-SAVEREDS) was set up for the Sciurus vulgaris conservation in Umbria through an eradication campaign of grey squirrels. One hundred and fifty-four animals were analysed for bacteriological, mycological, virological, and serological investigations (C4 action). Sanitary screening showed that Sciurus carolinensis is a dermatophyte carrier, and therefore, it could cause public health issues for humans, considering its confident behaviour. Moreover, it has been marginally responsible for the spreading of Candida albicans, Coxiella burnetii, and Borrelia lusitaniae. Health status evaluation conducted on the Sciurus carolinensis population indicated that it is necessary to raise awareness of its impacts on biodiversity and human health. Moreover, the health status and behaviours of the IAS must be considered when control or eradication campaigns are planned.