A reappraisal of the stratigraphy of Cueva del Llano (Fuerteventura) and the chronology of the introduction of the house mouse ( Mus musculus) into the Canary Islands

Major ecological changes related to anthropogenic activities begin on islands with initial human settlement. Key factors to understanding insular Holocene ecological changes are the arrival dates of both humans and alien species to the islands. In this context, finely stratified fossil sites are powerful tools to study the chronology and causes of these changes. Previous work, based on conventional 14C ages of land snails coming from the finely stratified site Cueva del Llano at Fuerteventura (Canary Islands, eastern Atlantic Ocean), indicates that one of the major ecological changes that took place in this archipelago–the arrival of house mouse Mus musculus–occurred around 7000 yrs ago, thus before the first arrival of humans to the islands. To extend these studies, we obtained 14C ages by accelerator mass spectrometer (AMS) directly on bone collagen from selected bones of rodents: lava mouse Malpaisomys insularis and house mouse, from seven sites: Cueva del Llano, Cueva de Villaverde and Malpaís de La Arena I & II (Fuerteventura), El Bebedero and Jameo de la Puerta Falsa (Lanzarote), and Barranco de la Baranda (La Palma). The new ages derived from the upper levels of Cueva del Llano (CLL 9.1–9.2) indicate a very young age for these materials, between 1667–1949 and 1261–1391 cal AD. These results support a more recent and very different chronology for the Holocene ecological changes that occurred on these islands compared to previous studies. Explanations for the stratigraphically anomalous age shown in previous papers are put forward. On the other hand, the available 14C ages indicate that the house mouse arrived on the eastern Canary Islands some time between 756 cal BC–313 cal AD and, probably from there, spread to the other islands before European contact.