A synthesis of terrestrial species extinctions in the Macaronesian Islands and their correspondence with human occupancy

Abstract

We present the first synthesis of all known terrestrial endemic species extinctions in the biogeographical region of Macaronesia, covering all archipelagos (Azores, Madeira, Selvagens, the Canaries, and Cabo Verde) and multiple taxa (arthropods, birds, bryophytes, fungi, land molluscs, lichens, mammals, reptiles, and vascular plants). This list also includes information on the original distribution of extinct species, extinction chronologies, and likely causes of extinction, as reported by the original works' authors. Our survey identified 220 extinction records, with the highest numbers observed among land snails (111 species), arthropods (55), birds (27), and reptiles (15). The proportional impact of extinction was greatest among vertebrates: birds (50% of the original endemics lost), mammals (43%), and reptiles (28%). Very few extinctions were recorded in vascular plants or bryophytes, and none in fungi or lichens. However, these low levels of loss may partly reflect the scarcity of historical and fossil records for these taxa. Exactly half of the recorded endemic species losses (including nearly all vertebrates, as well as the arthropods and vascular plants) have extinction chronologies matching with the human occupation of the islands, providing a minimum estimate of the number of extinction events that may be directly or indirectly attributed to human activities.

Keywords: Macaronesia; anthropogenic change; biodiversity loss; human colonization; island extinctions.

Fig. 1.

Artist reconstructions of some Macaronesian extinct birds. A) São Jorge rail (Rallus nanus) from São Jorge Island (Azores). B): Madeiran Scops Owl (O. mauli) from Madeira Island. C) Slender-billed greenfinch (Ch. aurelioi) from Tenerife (Canary Islands). D) São Vicente Quail (Co. centensis) from São Vicente Island (Cape Verde). Art by Pau Oliver (A, B, and D) and Aina Bonner (C). Sources: (22–26).

Fig. 2.

Map of the Macaronesian biogeographical subregion, showing the number of larger islands and their emergent geological age range. Source: extracted with kind permission from Florencio et al. (107) (https://doi.org/10.3389/fevo.2021.718169).