Birds (Vertebrata: Aves) are some of the most iconic animals. They play important roles in the ecosystem, and since they are abundant and diverse in most urban and rural areas, humans have established a good long-lasting relationship with them (e.g., birdwatching, photography). However, amongst the ca 10.000 bird species which have been living on Earth since the appearance of modern humans, many species were regionally lost or extinct, or are endangered, especially on islands (Sax et al. 2002, Elphick et al. 2010, Rando et al. 2013, Alcover et al. 2015). Updating a list of birds from remote oceanic islands represents an important step towards an improved knowledge of colonization mechanisms and migratory patterns by animals and a contribution towards the conservation and management of insular taxa and their natural habitats.

The Azores Archipelago is located in the North Atlantic Ocean, between 36°55’ and 39°43’ N, and 24°46’ and 31°16’ W, about 1500 km from mainland Europe and 1900 km from North America (Fig. 1). The Azores is a volcanic oceanic archipelago consisting of nine islands and several islets of recent volcanic origin (0.25 to 8.12 My old), which are spread over >600 km along a northwest-southeast transect (França et al. 2003). The oceanic distribution of these islands and, as a consequence, their relative positions, has led to the formation of the following groups: (i), a western group, comprising the islands of Flores and Corvo; (ii), a central group, with the islands of Faial, Pico, São Jorge, Terceira and Graciosa and (iii), an eastern group, made up of the islands of São Miguel and Santa Maria.

Figure 1.

Map of Azores islands, Portugal (Modified from Amorim 2005).

Due to its remoteness, the Azores archipelago was discovered and humans settled only at the beginning of the fifteenth century. The settlers described the islands as covered by dense native vegetation, with countless birds, especially seabirds (Frutuoso 2005a, Frutuoso 2005b, Frutuoso 2005c). Until then the archipelago was definitely a bird paradise, not only for seabirds that could use the vast coastal cliffs of the islands and islets to breed, but also for terrestrial birds which were widespread in the lush Azorean forests (Rodrigues and Cunha 2012). After human colonization started in 1439, several bird species suffered a sudden decrease in population size due to their use as food and oil source for human consumption, as well as to the introduction of predators and the destruction of their habitat (Rodrigues et al. 2010). As a consequence of the human impact, six flightless bird species are confirmed to be extinct in the Azores, namely one Otus species (Rando et al. 2013) and five Rallus species (Alcover et al. 2015), but recent findings indicate that many more will be described soon (Josep Alcover and Juan Rando, pers. comm.).

Despite the reduction of several bird populations, the Azores remain of great interest for ornithologists and are considered as one of the most popular destinations for European birdwatchers (Pereira 2010, Rodrigues and Michielsen 2010), all the more since they hold two endemic species: the Azores Bullfinch (Pyrrhula murina Godman, 1866) (Fig. 2), and Monteiro’s Storm Petrel (Oceanodroma monteiroi Bolton et al. 2008) (Fig. 3), and 11 endemic subspecies. Besides, the Azores archipelago displays colonies of several seabird species of great importance in the European context, and it is also possible to observe pelagic birds and a large variety of migratory birds, some of which are very rare Nearctic vagrants to the western Palearctic (Rodrigues and Michielsen 2010, Barreiros et al. 2014).

Figure 2.

Azores Bullfinch (Pyrrhula murina Godman, 1866). Photo by PAV Borges (2008).

Figure 3.

Monteiro’s Storm Petrel (Oceanodroma monteiroi Bolton et al., 2008). Photo by PH Silva (2014).

Rodrigues and Cunha (2011) resumed the ornithological history of the Azores, from the beginning of human settlement until recently, and the latest checklist of birds from the Azores archipelago was published in 2010 by Rodrigues et al., as part of the complete list of Azorean biota published by Borges et al. (2010). This list was based on an exhaustive review of the published literature (e.g., Le Grand 1993, Monteiro et al. 1996, Monteiro et al. 1999, Elias et al. 2003, Elias et al. 2004, Elias et al. 2005, Elias et al. 2006, Bried et al. 2007, Jara et al. 2007, Jara et al. 2008, Bolton et al. 2008, Imber 2008, Vittery 2014) but also on unpublished data following Rodebrand (2010) and Rodebrand S. & The Birding Azores Team (2010). This checklist totalled 384 species, distributed between three categories: breeding, non-breeding and potentially breeding (species reported as introduced and/or escapes from captivity and for which suitable nesting conditions exist in the Azores, but whose numbers are insufficient to allow the maintenance of self-sustaining populations in this archipelago). During the last years, and due to the growing interest of birdwatchers in the Azores avifauna, several dedicated websites have been developed, such as ABC – Azores Bird Club. (2014) (formerly Birding Azores) (http://www.birdingazores.com/), AdA – Aves dos Açores (2014) (http://azores.avesdeportugal.info/) and ABS – Azores Bird Sightings (2014) (http://azoresbs.weebly.com/ from January 2012 to February 2014 and http://azoresbirdsightings.blogspot.co.uk/ from August 2014 onward). These websites are presently used by birdwatchers as a tool to register new information about species occurrence and distribution in the Azores.

The present paper updates the previous checklist (Rodrigues et al. 2010), with respect to species distribution within the archipelago and also by including new species to the archipelago. The updating is based on the sightings reports available on the websites mentioned above. We also perform a nomenclatural review of the Orders, Families, Species and Subspecies, following the 2014 IOC World Bird list (v 4.3) (Gill and Donsker 2015) published by the International Ornithologists’ Union (available at http://www.worldbirdnames.org/). Some additional notes on the distribution of the different species among the islands and their biogeographic origin are presented.