Terrestrial Fauna of Azores
Located in the North Atlantic Ocean, the Azores archipelago is composed of nine islands of volcanic origin. Together with Madeira, the Canary Islands and Cape Verde, the Azores form part of the Macaronesian biogeographical region, an important world biodiversity hotspot which includes the Laurisilva Forest. The Azores have a geological, architectural, cultural and immaterial heritage of immense value. Its islands are an award-winning "sustainable tourism destination" offering unforgettable natural experiences focused on the preservation of its natural heritage rich in biological diversity, with a total number of species and subspecies estimated at 11,347, of which 7830 (69%) are terrestrial and freshwater species, including 580 unique endemic species.
This philatelic issue features four representatives of Azorean terrestrial fauna from three different groups: arthropods, molluscs and birds.
Terrestrial arthropods are the most diverse group of invertebrates in the archipelago, with a total of 2420 species and subspecies, 1854 of which are insects, 42 are myriapods, 92 are crustaceans and 329 are arachnids, including 133 spiders (such as the endemic Azorean wolf spider, Pardosa acorensis). Insects include 585 beetles, 428 flies, 338 true bugs, 163 hymenoptera species and 159 butterflies and moths (including the endemic cabbage butterfly, Pieris brassicae azorensis). Their distribution over the various islands is uneven, being found in greater numbers on the larger islands (São Miguel, Terceira and Pico). To date, a remarkable count of 276 endemic species and subspecies of arthropods, along with an additional 793 native non-endemic species, have been documented in the Azores.
Molluscs are another large and highly endemic group in the Azores. Of the 126 terrestrial, freshwater and halophilous mollusc species, 53 (42%) are endemic (such as the São Miguel snail, Oxychilus volutella). Due to its greater geological age, the small island of Santa Maria shelters 21 endemic species, seventeen of which are exclusive to the island. This richness of endemic species in the Azorean malacofauna is scientifically important, making the archipelago a natural laboratory where evolutionary processes can be studied in real time.
The inland water bodies are host to several aquatic species of the Oligochaeta and Acari classes and of the Copepoda subclass, as well as several arthropods of the Diptera, Coleoptera, Heteroptera, Trichoptera and Odonata orders. We note in particular the "crown jewel" of the Azorean dragonflies, Ischnura hastata, whose populations made up exclusively by females are a unique example in the world of parthenogenetic reproduction.
Terrestrial vertebrates are estimated to number 71 resident species and subspecies. Of these, birds are the most important group, represented by 37 regular breeding species and subspecies and several migratory species. The population abundance of terrestrial birds varies according to the habitats and elevations. There are twelve endemic species and subspecies, including the Azores bullfinch, Pyrrhula murina, a passerine bird that nests in the Laurisilva forest in eastern São Miguel, as well as the common starling, Sturnus vulgaris granti. There are only two resident predatory birds: the kite and the owl. Around twenty mammals belonging to the orders Carnivora, Chiroptera, Rodentia, Lagomorpha, Insectivora and Ungulata are known on the islands. With the exception of the endemic Azores bat Nictalus azoreum, observable during the day, the species of the remaining orders are of anthropogenic introduction. There are also five indigenous domestic animal breeds, including two dogs (the São Miguel Cattle Dog and the Barbado da Terceira), two equines (the Dwarf Donkey of Graciosa Island and the Terceira Pony), and a bovine (Ramo Grande). There are two amphibians (the green frog and Northern crested newt), two reptiles (the Madeiran wall lizard and the gecko) and thirteen freshwater fish – all introduced, with the exception of the eel.
Virgílio Vieira | Paulo A. V. Borges cE3c – Azorean Biodiversity Group University of the Azores
António M. Frias Martins CIBIO-Azores University of the Azores