Taxonomy of the Rock/Water Pipit superspecies Anthus petrosus, spinoletta and rubescens

Alan Knox

t the time of the last British checklist (BOU 1971), the Rock and AWater Pipits were generally regarded as one polytypic species of Holarctic distribution, Anthus spinoletta. This species ranged from western Europe to eastern Siberia, across North America from Alaska to western Greenland and southwards along the Rocky Mountains. Recently, the British Ornithologists' Union Records Committee, on the recommenda­ tion of its taxonomic working group, decided to treat these pipits as a superspecies composed of three species, A. petrosus, A. spinoletta and A. rubescens, all of which occur or have occurred in Britain and Ireland (BOURC 1986; table 1). In this paper, I shall briefly give the background to this decision.

Geographic variation Many of the subspecies within the original Rock/Water Pipit complex (table 1) grade into one another to some extent. This is particularly so with the forms in western Europe, where a cline runs from the longer- billed and darker 'kleinschmidti' (see below), through petrosus, to the shorter- billed and paler littoralis (Hall 1961). These races also vary in the extent to which they undergo a moult in late winter. In the cases of 'kleinschmidti' and petrosus, the winter plumage is largely retained and the birds are dark and heavily streaked as the breeding season approaches. A distinctive spring plumage is acquired by littoralis, to a degree which varies between individuals. Some petrosus from Ouessant, France, appear to be intermedi­ ate, and moult into littoralis-\\ke spring plumage (Mayaud 1952). Although the northern end of this cline is called kleinschmidti, this form is

206 [Brit.Binha1:206-211,May I9RB] Taxonomy of Rock/Water Pipits 207 only poorly differentiated and arbitrarily separated from petrosus. Its geographic range is not clear (Vaurie 1959; Hall 1961; Williamson 1965). As with several other names given to stages in this cline, it is perhaps best synonymised (BOUTS 1956). The acceptable northwestern forms (petrosus and littoralis) differ from the remaining subspecies in being more olive- brown instead of greyish on the upperparts, especially the rump, with the underparts more extensively streaked and washed with yellow-buff, and by the outer-tail pattern being dusky rather than pure white. Nominate spinoletta is more lightly streaked, and the underparts are flushed with pale pink in spring. The Middle Eastern form, coutellii, is smaller than nominate spinoletta, and more heavily streaked, with more orange tones and a warmer pink on the breast in spring. A. s. blakistoni is paler than either nominate spinoletta or coutellii, and less heavily streaked than the latter. More distinctive than either coutellii or blakistoni, japonicus is dark, with heavy spotting in autumn. The underparts in spring are sparsely marked, and washed orange-buff rather than pink. The white in the tail is more extensive, and the legs are pale. The North American races are all similar to japonicus, although warmer brown in autumn, and with lighter streaking. In spring, they are greyer and darker above, with little or no streaking below. The legs are dark. The populations in western North America tend to be paler than those farther east, and may not be separable. The race in the Rocky Mountains, alticola, has a rich spring plumage. (Plumage notes based on Hall 1961 and Vaurie 1959.) Table 1. The subspecies of the Rock/Water Pipit superspecies (based on Hall 1961 and Vaurie 1959) * Regarded here as synonym of petrosus I. Conspecific under the name A. petrosus 2. Conspecific under the name/1, spinoletta 3. Conspecific under the name A. albescens

Subspecies Breeding distribution

[kleinschmidti* Faroe Islands and possibly Scottish outlying islands] 1 petrosus Ireland, Britain, northwest France 1 littoralis Fennoscandia and northwest Russia 2 spinoletta Southern and central F'.urope 2 coutellii Asia Minor, Caucasus and Iran 2 blakistoni Central Asia 3 japonicus Eastern Asia 3 pacificus Western North America 3 rubescens Eastern North America and western Greenland 3 alticola Central and southern Rocky Mountains

Separation of 'A. rubescens' from 'A. spinoletta' Recent work in the USSR has shown that blakistoni and japonicus live 'side by side' in Transbaykalia (Nazarenko 1978). The two forms were found to occupy different habitats, blakistoni inhabiting 'tundra' with few or no rocks, and japonicus (which was much rarer) on parts of the same 'tundra' where rocks were abundant. There was no evidence of hybridisation, and Nazarenko believed that the two populations were behaving as different species. Shirihai & Colston (1987) have provided further references to the 208 Taxonomy of Rock/Water Pipits

Fig. 1. Breeding distributions of Rock Pipit Anthus petrosus (black), Water Pipit A. spinoletta See Table 1 for Soviet literature which confirm the differences between these taxa. Since the North American races are thought to be closely related to japonicus, all these forms are now best removed from A. spinoletta (which includes blakistoni), under the name A. rubescens (this being the oldest name within the newly separated species). Alstrom & Mild (in press & in prep.) consider that morphological and vocal differences alone would justify the separation of these species. There have been four records of A. r. rubescens in Britain and Ireland: St Kilda in September 1910, Wexford in October 1951, Fair Isle in September 1953, and Wicklow in November 1967 (BOU 1971). Three other records, one of which predates the above, are still under consideration. Elsewhere in Europe, there have been three records of this subspecies from Helgoland (November 1851, May 1858 and September 1899), and one in Italy (November 1951)(Glutz 1985). A. r. japonicus is a scarce, but regular, passage migrant and winter visitor to the Middle East (Shirihai & Colston 1987; Alstrom & Mild in press), and there is one European record, from Italy in October 1960 (Bonfio 1962).

Rock and Water Pipits The original concept of A. spinoletta (i.e. including A. rubescens) comprised two distinct ecological groups of races—the petrosus group (petrosus and littoralis, together known as the Rock Pipits) and the spinoletta group (all the remaining races, known as the Water Pipits). During the breeding season, the former is largely confined to the rocky coasts of northern and western Europe, whereas the latter 'consists predominantly of inland forms occurring on tundras, barren tracks, alpine pastures, and rocky grassy slopes with or without scrub, and particularly along streams' (Vaurie 1959). Although Rock and Water Pipits are entirely allopatric during the breeding season, they are sometimes found alongside one another in winter. Bijlsma (1977) studied littoralis and nominate spinoletta at one such Taxonomy of Rock/Water Pipits 209

stippled) and American Pipit A. rubescens (vertical shading) (after Glutz 1985). fistribution of races site in the Netherlands. He found differences in the distribution of the two forms between the available habitats, with spinoletta in wetter places than littoralis: where they occurred together, they were separated by microhabi- tat. It is sometimes found that conspecific subspecies differ in the habitats they utilise while on passage or in winter (e.g. Yellow Wagtail Motacilla flava subspecies: Fry et al. 1972), but this is usually the case also with distinct species. Bijlsma found that his Rock and Water Pipits roosted in different habitats. In Britain, Water Pipits roost communally, unlike Rock Pipits (Biber 1986). Rock and Water Pipits have also shown different food and habitat requirements within Britain, spinoletta particularly avoiding saline environments (Gibb 1956; Johnson 1966, 1970; Biber 1986). The main plumage differences between the groups are described above, but they are not absolute. Some littoralis, for example, have greyish tones on the upperparts and Konigstedt & Miiller (1983) reported that 'exceptional individuals [of nominate spinoletta] cannot be separated from littoralis on tail feather colouration alone.' Under these circumstances, other characters must be used as well: either plumage features, or perhaps vocalisations.

Separation of 'A. petrosus' from 'A. spinoletta' The Rock and European Water Pipits are generally quite distinctive and easy to identify. Their breeding ranges are widely separated, and they occupy very different habitats: the former coastal, the latter montane. During winter, they have different ecological requirements. There are clearly good reasons for considering them to be different species. Allopatric breeding populations frequently cause difficulties for tax- onomists: there is no direct evidence as to whether the forms would or would not successfully interbreed if they were to come into contact. The morphological and ecological differences between Rock and Water Pipits in Europe are, however, at least as pronounced as those between A. s. blakistoni and A. r. japonicus. We believe, therefore, that it is appropriate to treat the petrosus and spinoletta groups as separate species. 210 Taxonomy of Rock/Water Pipits The BOU proposes to treat the British forms of the superspecies in the following manner: A. petmsus petrosus ~\ „ ,,. • .4. petrosus Uttoralis J " .4. spinoletta spinoletta Water Pipit ,4. albescens mbescens American Pipit The sequence conforms with the principles used by Voous (1977): Anthus is an Old World genus; the exclusively Palearctic taxa are therefore placed first, with mbescens following. This order also places each taxon next to its presumed nearest relative (of those on the British and Irish List). The suggested English name for mbescens—American Pipit—follows earlier usage, and describes the geographic origin of the individuals which have occurred in Britain. It is not entirely satisfactory if applied to the whole species, and the alternatives of Buff-bellied Pipit and Holarctic Pipit have been suggested. The Rock Pipits were treated as separate species by Bannerman (1953) and, more recently, by Oreel (1980) and Devillers (1980). The Middle European handbook (Glutz 1985) and Devillers (1980) treated the American Pipit as a separate species. Johnson (1970) has reviewed the identification and distribution of Rock and Water Pipits within Britain.

Acknowledgments This paper is based on a report that was prepared for the BOURC. I am grateful to the other members of the Committee for their comments at that stage. Through Peter Grant, G. J. Oreel provided a translation of the relevant notes to the Dutch checklist. M. G. Wilson kindly translated Nazarenko's paper. I have particularly benefited from discussions and correspondence concerning pipits with Lars Svensson and Per Alstrom. I. R. Bishop and Robert Hudson commented on the manuscript.

References ALSTROM, P., & MILD, K. In press. Some notes on the taxonomy of the Water Pipit complex. International Bird Identification. Eilat. BANNERMAN, D. A. 1953. The Birds oj the British Isles, vol. 2. Edinburgh. BlIiKK, J. P. 1986. Rock Pipit and Water Pipit. In LACK, P. The Atlas of Wintering Birds in Britain and Ireland, pp. 296-299. Gallon. BlJLSMA, R. 1977. Voorkomen en oecologie van Anthus spinoletta en A. s. Uttoralis in de uiterwaarden van de Rijn bij Wageningen. I.imosa 50: 127-136. BoNEIO, A. 1962. Catturata in Italia una nuova forma di Spioncello: Anthus spinoletta japonicus. Riv. Hal. Om. 32:51-54. BRITISH ORNITHOLOGISTS' UNION (BOU). 1971. 77K Status of Birds in Britain and Ireland. Oxford. BRITISH ORNITHOLOGISTS' UNION RECORDS COMMITTEE (BOURC). 1986. Twelfth report. Ibis 128:601-603. BRITISH ORNITHOLOGISTS' UNION TAXONOMK: SIB-COMMITI EE (BOUTS). 1956. First report. Ibis 98: 157-168. DENNIS, R. H. 1982. Scottish Bird Report 1981. Scot. Birds 12 (special issue). DEVILLERS, P. 1980. Projet de nomenclature Frangaise des Oiseaux du Monde. I.e Gerfaut 70: 121-146. FRY, C. H., FTRGISON-LEES, I. J., & DOWSE/IT, R.J. 1972. Flight muscle hypertrophy and ecophysiological variation of Yellow Wagtail Motacilla ftava races at Lake Chad.y. Zoo/., Ijmd. 167:293-306. GlBB, J. 1956. Food, feeding habits and territory of the Rock Pipit Anthus spinoletta. Ibis 98: 506-530. GI.IT/, N. (ed.) 1985. Handbuch der Vbgel Mitteleuropas. vol. 10/11, Part 1. Wiesbaden. Taxonomy of Rock/Water Pipits 211 HAM., B. P. 1961. The taxonomy and identification of pipits (genus Anthus). Bull. BM (NH) 7: 243-289. JOHNSON, I. G. 1966. Water Pipits wintering on watercress beds. Brit. Birds 59: 552-554. 1970. The Water Pipit as a winter visitor to the British Isles. Bird Study 17: 297-319. KONIGSTF.D, D., & MCl.I.ER, H. E.J. 1983. Zur Unterscheidung von Bergpieper (Anthus spinoletta spinoletta) und Felsenpieper (Anthusspinoletla litloralis). Beitr. Vogelkunde 29: 77-88. MAYAUD, N. 1952. Le phylum marin cVAnthus spinoletta: ses particularity ecologiques et morphologiques. Alauda 20: 65-79. NAZARENKO, A. A. 1978. [On species validity of Anthus rubescens Tunstall (Aves, Motacilli- dae).] Zool. Zh. 57: 1743-45. OREEL, G.J. 1980. Dutch Birding Association Checklist. Deel 2. Dutch Birding 2: 82-104. SHIRIHAI, H., & COLSTON, P. R. 1987. Siberian Water Pipits in Israel. Dutch Birding9: 8-12. VAURIE, C. 1959. The Birds of the Palearctk Fauna. Passeriformes. London. Voous, K. H. 1977. List of recent Holarctic bird species. Ibis 119: 223-250. WILLIAMSON, K. 1965. Moult and its relation to taxonomy in Rock and Water Pipits. Brit. Birds 58: 493-504.

DrAlan Knox, Sub-department of Ornithology, British Museum (Natural History), Tring, Hertfordshire HP23 6AP

A paper on the identification of these three species is currently in preparation by Per Alstrom and Krister Mild for publication in British Birds. EDS