Madeira Firecrest - Taxonomy

Taxonomy

The kinglets are a small group of birds sometimes included in the Old World warblers, but frequently given family status, especially as recent research showed that, despite superficial similarities, the crests are taxonomically remote from the warblers. The names of the family, Regulidae, and its only genus, Regulus, are derived from the Latin regulus, a diminutive of rex, "a king", and refer to the characteristic orange or yellow crests of adult kinglets. The species name madeirensis is derived from the island on which this bird is found. The Madeira Firecrest was first described by English naturalist Edward Vernon Harcourt in 1851. Until recently, it was considered to be a subspecies, R. i. madeirensis, of the Common Firecrest R. ignicapillus. A phylogenetic analysis based on the cytochrome b gene showed that the Madeiran form is distinct at the species level from the Firecrest nominate subspecies R. i. ignicapillus. Cytochrome b gene divergence between the Madeira Firecrest and the European bird is 8.5%, comparable with the divergence level between other recognised Regulus species, such as the 9% between the Goldcrest and the Golden-crowned Kinglet. The split was accepted by the Association of European Rarities Committees (AERC) in 2003, but some authorities, such as Clements, have not yet recognised the new species.

The songs of the four subspecies of Common Firecrest (nominate R. i. ignicapillus, Mediterranean R. i. balearicus, southeastern R. i. caucasicus and North African R. i. laeneni) show a number of different song forms, but in general are very similar to each other, whereas the Madeiran Firecrest has only one song type, which is divided into three phrases, two of them consisting of modified display and anger calls. Its display calls use a larger frequency range and more harmonics than the continental subspecies. Male Common Firecrests do not show a territorial response to recordings of the songs or calls of the Madeiran taxon, although Madeiran Firecrests do react strongly to playback of the calls of the mainland birds. The island form was recognized as a separate species on the basis of differences from the mainland form in morphology, vocalisations, and genetics.

The Atlantic archipelagos of the Canaries, Azores, and Madeira have a volcanic origin and they have never been part of a continent. The formation of Madeira started in the Miocene and the island was substantially complete 700,000 years ago. In the distant past the major islands of these archipelagos were all colonised by Regulus species, which evolved on their respective islands isolated from mainland populations. The Firecrest descendant evolved in Madeira and Goldcrest subspecies evolved on the other islands. Cytochrome b gene divergence between Common Firecrests from Europe and Madeira Firecrests suggests an evolutionary separation roughly 4 million years ago, considerably earlier than the 2.2 million years ago maximum estimate for the Goldcrest radiations in the Canaries and Azores.