Sheet	Content	Explanation	
Sheet 1	References of reports likely to contain relevant primary observations of impacts but which we could not be assessed (because the report was not accessible or written in a language not spoken by the assessor)	"These references were recorded to guide future attempts to complete the assessment of the impacts caused by alien ungulates, and to complement the EICAT assessments performed so far, by showing additional impacts caused by alien ungulates. When available, information on the EICAT impact magnitude, mechanism, location, and on the impacted species was collected (otherwise ""n.a.""). Uncertainty around the impact magnitude was not evaluated, as non-primary reports do not provide details on the way the observations were led. "	
Sheet 2	References of not relevant reports (not assessed with EICAT)	"We recorded reports which seemed to contain relevant impact observations, but which we considered as non-relevant for EICAT assessments (and hence did not assess), along with the reasons why they were considered non-relevant. This is to ensure the transparency of our EICAT assessments. "	
Sheet 3	Introductions of alien ungulate	"The countries to which each alien ungulate species has been successfully introduced have been collected from Long (2003), the EICAT assessments performed in this study (see Sheet 4), and four databases: the CABI's Invasive Species Compendium (ISC; accessed in November 2020), the Global Biodiversity Information Facility (GBIF; accessed in November 2020), the IUCN Red List of Threatened Species (accessed in November 2020), and the Global Register of Introduced and Invasive Species (GRIIS; accessed in 2017). "	
Sheet 4	EICAT assessments	We classified each relevant impact observation with the EICAT classification.