The ‘Northern Bullfinch’ invasion of autumn 2004 Mike G. Pennington and Eric R. Meek Alan Harris ABSTRACT A record invasion of ‘Northern Bullfinches’ Pyrrhula pyrrhula pyrrhula occurred in Britain in autumn 2004. It also affected many other parts of Europe with birds being recorded as far afield as Iceland, Ireland, Italy and Bulgaria. As well as in Britain and Ireland, record numbers were seen in parts of Scandinavia and several countries in central and eastern Europe. Field identification of ‘Northern Bullfinches’ is difficult, as there is no single diagnostic feature. However, trapped birds are easily separable using biometrics (particularly wing length). Many, but not all, birds in the 2004 influx were giving a distinctive call, which became known as the ‘trumpet call’.This call is not diagnostic of Northern Bullfinch, as birds over most of the range of this subspecies give a call hardly distinguishable from that of ‘British Bullfinch’ P. p. pileata.Although the ‘trumpet call’ was unfamiliar to most observers and attracted much attention, it was soon established that birds giving such a call had been recorded in northern and western Europe before. Speculation on the birds’ origin was widespread, and research so far has suggested that European Russia is the most likely source (a recording from the Komi Republic matches the ‘trumpet’ call), although others, possibly lingering from previous influxes, have been heard farther west in the breeding season. 2 © British Birds 99 • January 2006 • 2–24 The ‘Northern Bullfinch’ invasion of autumn 2004 n autumn 2004, large numbers of other parts of Europe. The identification of Bullfinches Pyrrhula pyrrhula began moving Bullfinch races is discussed, given the wide- Ithrough northern Europe. Although the spread debate on field characters, although the numbers were remarkable in themselves, it was results are inconclusive. The debate on whether the unusual and frequently given calls of these or not the ‘trumpet’ calls heard in 2004 were as birds which aroused most interest. This call was unusual as was first suspected, and the pre- soon dubbed the ‘trumpet call’ in many coun- sumed origins of these ‘trumpet’ callers are also tries, and debates raged on message boards and discussed. Relevant background information is mailing lists about its significance, and the given to put the 2004 influx in context. origins of the birds themselves; some observers Another interesting aspect of this influx was began to refer to them as ‘Siberian’ birds or sug- the amount of information that was posted on gested that they belonged to an ‘eastern race’. It websites within a day or two of the actual sight- soon transpired that some of the claims being ings. The public-access record system in Sweden made were unfounded, but it also became clear (Artportalen) and BirdGuides in Britain pro- that there were several intriguing aspects of the vided much useful information, but several autumn movement, and that there are still other sites were used. Appeals for information many things to discover even about a common were also made in British Birds and on several and familiar species such as the Bullfinch. It is internet mailing lists, the internal AERC (Asso- worth remembering that, unlike the situation ciation of European Rarities Committees) with other irruptive northern European species, mailing list proving particularly useful. Other the reasons for influxes of Bullfinches into information came from contacts established western Europe are largely unknown (Clement during the research, an effort being made to et al. 1993; Cramp & Perrins 1994), although check data with a local contact wherever pos- they are presumably related to failures of an sible. The extensive range of sources is indicated important seed crop(s) used as a food source. in the acknowledgments list. Several correspondents suggested that Rowan Sorbus aucuparia berries were an important Bullfinch distribution and taxonomy autumn food source in their area, so perhaps Bullfinch is the only widespread species of the high population levels following a good genus Pyrrhula, which includes five other, Asian breeding season in a poor Rowan-crop year may species. Sometimes known as Eurasian or be the trigger for movements. Common Bullfinch, it breeds principally in Information on the scale of the 2004 influx woodland in the boreal zone of the Palearctic, is presented here, showing it to be the largest on although it may be found farther south in record in Britain and Ireland, as it was in several Europe, where it breeds to sea level in scrub and © Fluke Art © Fluke Fig. 1. Breeding range of Bullfinch Pyrrhula pyrrhula based on Clement et al. (1993).The exact range of the easternmost races is particularly uncertain. British Birds 99 • January 2006 • 2–24 3 The ‘Northern Bullfinch’ invasion of autumn 2004 woodland in temperate areas, as well as in mountains as far south as northern Iberia, Italy and the Balkans. There are also southerly populations in the Caucasus Mountains, southwest Asia and Japan. Clement et al. (1993) recognised ten races (fig. 1), three of which are sometimes separated as distinct species: male ‘Baikal’ or ‘Grey Bullfinch’ P. (p.) cineracea has grey underparts and lacks pink on the cheeks; male ‘Japanese Bullfinch’ P. (p.) griseiventris (including ‘rosacea’ and ‘kurilensis’, usually considered synonymous with griseiventris) has pink cheeks, with the rest of the underparts grey or faintly tinged pink; while ‘Azores Bullfinch’ P. (p.) murina shows no sexual Arie Ouwerkerk dimorphism, and both sexes have a buffish rump. The remaining six races are extremely similar and varia- tion is slight, involving mainly size and subtle tones of plumage. The nominate race breeds over the great majority of the species’ range but there are three other races in western Europe: iberiae in northern Iberia, pileata in Britain and Ireland and europoea in western continental Europe. Two other races, ‘coccinea’ and ‘germanica’ are usually sub- sumed within europoea and pyrrhula respectively, but they are indicative of the fact that there is no clear division between europoea and the nominate race. In southwest Asia, rossikowi (including ‘paphlagoniae’) breeds in northern Turkey and the Cau- Arie Ouwerkerk casus and caspica is found in 1 & 2. ‘Northern Bullfinches’ Pyrrhula p. pyrrhula,Terschelling,Friesland, northern Iran. The only pink- The Netherlands, December 2004.These birds, known to be ‘trumpet- callers’, were photographed during the autumn 2004 invasion; hopes that breasted eastern race is cassinii, they might show distinctive plumage features as well as having the which breeds in far-eastern distinctive call have not been upheld by research to date. Siberia. 4 British Birds 99 • January 2006 • 2–24 The ‘Northern Bullfinch’ invasion of autumn 2004 Hugh Harrop 3. Male ‘Northern Bullfinch’ Pyrrhula p. pyrrhula, Lerwick, Shetland, October 2004. Movements of Bullfinches Asia. Northern Bullfinches are also eruptive and Bullfinches may be found in breeding areas in invasions are recorded regularly in Scandinavia, western Europe throughout the year, but although whether these involve birds from several races are migratory. In the eastern within Fennoscandia or beyond is not always Palearctic, cineracea, cassinii and griseiventris clear. Ringing data suggest that relatively few are all migrants and, for example, cassinii has leave Fennoscandia and most long-distance been recorded in Japan and Alaska, while ciner- movements established from ringing have been acea has wandered as far as Korea (Clement et to/from central Europe (Cramp & Perrins 1994; al. 1993). In western Europe, there are two Niklas Lindberg pers. comm.). There was only fairly sedentary races: iberiae in northern Iberia one ringing recovery linking Britain and Scan- is believed to undertake mainly altitudinal dinavia prior to 2004: a bird ringed in Scotland movements, and pileata in Britain and Ireland in 1994 and recovered in Sweden in 1997 is thought to be highly sedentary as most (Wernham et al. 2002). In Denmark, generally British-ringed birds have been recovered within regarded as being on the boundary of the 20 km of where they were ringed (Summers breeding range of Northern Bullfinch, sporadic 1979; Wernham et al. 2002). There have been irruptions occur fairly regularly, the most recent some longer-distance recoveries of pileata, being in 1977, 1980, 1981, 1986, 1990, 1994 and however, nearly all in the 1960s when the pop- 1996 (Lausten & Lyngs in Bønløkke-Pedersen et ulation level was high. These included five al. in prep.). movements to or from the Continent, some of Irruptions of Northern Bullfinches have which could have involved the western Euro- been recorded in western Europe since the pean race europoea (which is not officially on nineteenth century: on Helgoland, Germany, the British List) and which is thought to be from 1847 (Gätke 1895), in Orkney since 1809 largely sedentary but may undertake move- (Booth et al. 1984) and Shetland since 1863 ments of up to 500 km (Cramp & Perrins (Pennington et al. 2004). Although these early 1994). British irruptions were not confirmed as The most migratory subspecies is the nomi- involving the nominate race, subsequent obser- nate, colloquially known as ‘Northern Bullfinch’ vations would suggest that this was highly likely. in Britain. The northernmost breeding areas of The first British specimens of Northern this race are abandoned in winter, when the Bullfinch were obtained from Lothian in 1884 range expands southwards, especially in central (Baxter & Rintoul 1953) and Yorkshire in 1894 British Birds 99 • January 2006 • 2–24 5 The ‘Northern Bullfinch’ invasion of autumn 2004 (Saunders & Clarke 1927). In recent years, Identification of Northern Bullfinch Northern Bullfinches have been recorded in Northern Bullfinches may seem distinctively Britain almost annually, but the great majority ‘large and bright’ when encountered on a have been in Shetland or Orkney. In Shetland, remote offshore island, but it is not always easy for example, records have been annual since the to be confident about such subjective features.