Sitta europaea Linnaeus, 1758
This Eurasian species, with a range stretching from the coasts of the Atlantic to the coasts of the Pacific, is the type and most studied species of its genus.
Voous & van Marle (1953), who listed numerous previous studies, recognised 40 subspecies in their broad concept of S. europaea; of which 22 fall within our geographical scope. Their map (reproduced here as Fig. 1) sets the scene for an examination of species limits.
The ‘species’ is shown occurring around the deserts and high plateaux of central Asia, but it does not complete the circle because of inhospitable terrain in lowland Pakistan and in most of Iran and Arabia. The hatched range of the ‘brown-breasted’ European forms is shown meeting, in a cross-hatched area, the ‘white-breasted’ forms of the Siberia taiga. A further cross-hatching west of Korea and Bo Hai, once known as the Gulf of Chihli, also represents a meeting of the white-breasted forms with further brown-breasted ones, of China south and south-west to the Naga Hills of NE India. These two cross-hatched areas are called ‘zones of hybridization’ by Voous & van Marle (1953). The term hybridization used by them here refers not to a meeting of species, but to intergradation between well-marked subspecies. To the south of China, and to the west of there in the Indian subcontinent, Voous & van Marle mapped the South Asian and South-east Asian range of ‘mahogany’ subspecies, which exhibit marked sexual dimorphism. The overlap between these – considered by Voous & van Marle in four groups, two with only a single taxon – and the brown-breasted Chinese forms, marked by the large query on their map, signals the difficulty in considering all 40 subspecies to belong to one species. The nature of the overlap, especially its altitudinal characteristics, required further elucidation, and is still insufficiently understood.
Vaurie (1957) recognised only 26 forms the last six of them making up the castanea group, of which he said “As this group is not Palearctic, it is not discussed here”, but he did defend koelzi Vaurie, 1950, which Voous & van Marle had not accepted. Vaurie also insisted that prateri Whistler & Kinnear, 1932, recognised by Voous & van Marle, did not appear to be separable from castanea, as propounded by him earlier (Vaurie, 1950). Excluding the castanea group, he accepted only ten subspecies for our region (see map in Editors’ Foreword). For one of these he used the name asiatica Gould, 1835, the validity of which Voous & van Marle had rejected, although without giving reasons.
Ripley (1959) elevated castaneato species level, at that stage including cashmirensis but later (Ripley, 1961) he removed this to S. europaea. Greenway (1967) followed Ripley (1959) in recognising castanea as a species, with all the races accepted by Vaurie plus inclusion of cashmirensis, even though Ripley had later decided to return it toeuropaea. What remained of S. europaea Greenway split into two species (europaea and nagaensis ). His species nagaensis was represented by two subspecies: nominate nagaensis – with montium la Touche, 1899, in synonymy – and grisiventris Kinnear, 1920. Otherwise, his narrower concept of the species S. europaea involved no reduction in the number of subspecies accepted in Asia, and only additional synonyms distinguish his list from Vaurie’s (although he placed kleinschmidti Hartert & Steinbacher, 1933, in the synonymy of amurensis Swinhoe, 1871 , rather than omit it as an intermediate – or ‘indeterminate’ hybrid).
Harrap (1996) followed Greenway in treating castanea and, with some reservations, nagaensisas species, but went further. He interpreted the treatment of Sibley & Monroe (1990) as allowing him to recognise cashmirensis as a species, although this proposal had never been made in a peer-reviewed journal. Unlike Greenway, he recognised montium (type locality: Kuatun, Fujian), as had Vaurie, and following Stepanyan (1990: 584) restored recognition of S.europaea sakhalinensis Buturlin, 1916. Morioka (1994), not cited by Harrap (1996), considered Hokkaido to be occupied by S. e. asiatica, all Honshu plus Shikoku and northern Kyushu by S. e. amurensis, and that S. e. roseilia Bonaparte, 1850, occupied only southern Kyushu.
The scope of this series does not include northern Siberia. Therefore arctica Buturlin, 1907, and albifrons Taczanowski, 1882, neither of which reach China or Japan, are not included here although discussed by Red’kin & Konovalova (2006; this issue), where the east Asian races of S. europaea are reviewed in a solicited complement to this paper. Their recommendations include recognition of subspecies takatsukasai Momiyama, 1931 from the Kurile Islands, hondoensis Buturlin, 1916, from much of Japan (contra Morioka, 1994) and formosana Buturlin, 1911, from Taiwan. They also strongly support the case made by Eck (1984) for the elevation of S. (e.) arctica (from north of our area)to full species rank.