New Additions to the Mammal List Documented in the Portuguese Red Data Book.

This study outlines the procedures used for collecting, processing, and categorizing data on 16 new mammal species for mainland Portugal, belonging to four taxonomic groups: Eulipotyphla (1), Chiroptera (4), Rodentia (2), and Cetacea (9). Data collection and processing encompassed field and lab work and bibliographic compilation. Data categorization involves, whenever possible, the assessment of the approximate number of mature individuals in populations, the extent of occurrence, and the area of occupancy. The approach employed led to the classification of eight out of the 16 species into an IUCN category: two non-volant small mammals and one bat species were designated as Vulnerable, requiring ongoing monitoring; one rodent and three cetaceans were assigned to Data Deficient due to insufficient available information; and a single bat species was classified as Least Concern due to the high abundance of local populations. For small mammals and bats, alterations to natural systems and climate change emerged as the most relevant threatening factors, while for cetaceans, human activities such as fishing, commercial shipping, and tourism were identified as the primary survival risks. It is recommended to maintain action programs that assist in defining strategic orientations for the implementation of conservation measures on a case-by-case basis.