The São Tomé shrew is threatened primarily by deforestation and habitat degradation (1). Ever since the Portuguese settled on the island in 1479, large areas of forest have been lost as land was converted for agriculture, such as sugar, coffee and cocoa plantations (2) (3). More recent deforestation is attributable to the construction of houses and gardens(1). Today, it is largely the remote and inaccessible areas of forest that remain untouched (3).
Invasive animal species have been both intentionally and unintentionally introduced to the island since its colonisation. These species include both domestic and feral pigs, goats, sheep, cats, dogs, weasels, civets, rats and mice (4). Rats and mice have similar niches to the shrew and so compete for resources, as well causing an increase in predatory bird populations (4), while weasels, civets and mongooses prey on shrews (4). Although not the sole cause of the decline in the São Tomé shrew population, it is thought that the impacts of these invasive species may act in concert with habitat destruction, to leave the São Tomé shrew in a perilous position (4).