Azores (or São Miguel) Bullfinch Pyrrhula murina (local name of Priôlo) is a very distinct form, which has only ever been known to occur at the east end of the island of São Miguel in the Azores archipelago (Portugal). Godman, who discovered the species, described it as one of the characteristic birds of mountainous areas on the island. The present population, of c120 pairs, is confined to the largest fragments of native vegetation (Macaronesian Laurel Forests). At the end of the last century it had a wider range and was regarded as a pest in orange orchards, being easily taken for museum collections. Native vegetation has been cleared for pasture and/or forested with the exotic Japanese Red Cedar Cryptomeria japonica, The remaining fragments have been invaded by aggressive exotic plants: Pittosporum undulatum, Hedychium gardneranum and Clethra arborea, Azores Bullfinch is now considered Endangered by IUCN and is included within the Portuguese Red Data Book. It is also included in Annex I of the European Union's Wild Birds Directive. In 1995, the local forestry service initiated a programme (with European Union funding) in an attempt to restore and expand the area of laurel forest and increase the population of Azores Bullfinch.
Azores Bullfinch differs markedly from its mainland counterpart, The sexes are virtually identical in coloration, although males sometimes possess a slight reddish-tawny suffusion on the vent and flanks. The traditional method of ageing Bullfinch Pyrrhula pyrrhula - colour differences in the greater coverts - is difficult to apply in Azores Bullfinch because adults have buffish-edged coverts too, unlike the greyer tones in mainland Bullfinch. Male Azores Bullfinches are significantly larger than females.
Population and habitat
Two main areas of native vegetation are present within the range of the Azores Bullfinch: the largest, centred on the Pico da Vara summit, where birds are resident, and Salto do Cavalo, in the west of the range, where it has been observed in September - December. The population was estimated at 30-40 birds in the late 1970s, 100 pairs in 1989 and 60-200 pairs in 1991-1996 (pers. obs.). Native vegetation is always preferred but there are seasonal variations in habitat selection: in summer, birds utilise bare ground, short vegetation and forest edges, including exotics, within 200 m of native forest. In January -April it is less catholic and virtually confined to native vegetation . Changes in habitat can be explained by seasonal variation in food resources between habitats: birds move from area to area following the fruiting of food plants. Therefore, the species is more mobile in summer, crossing areas of mature forest to reach areas with herbaceous plants. Colour ringing has demonstrated that longer movements (up to 3 km along streams) occur in May, with birds descending from c700 m to 300 m to feed on herbaceous seeds[l2].
Breeding and feeding
The species' behaviour in May and early June - bill caressing and twig display - indicates pre-breeding activity, Females with brood patches occur in mid-June - late August, suggesting a later and shorter breeding season than that of the mainland Bullfinch[l4]. Adults moult from September onward. I found two nests in 1992. The first was located in a low plantation (<5 m height) of C. japonica and the second within an area of C. arborea and native forest, but both were placed on a C. japonica tree at c3 m above ground. Nests were alike, consisting of an outer layer of twigs of C. arborea and Erica azorica and an inner layer of rootlets, grass and moss (Fig 2). The progressive appearance of juveniles in the field suggests two young are usually raised. Azores Bullfinch is a granivorous-herbivorous bird, consuming food from at least 37 different plant species, of which 13 are known to he important. In summer, birds take herbaceous seeds (Polygonum capitatum, Prunella vulgaris, Leontodon filii), in autumn seeds of fleshy fruits (Rubus sp., Vaccinium cylindraceum, Leicesteria formosa), in winter tree seeds (Clethra arborea) and fern sporangia (Woodwardia radicans, Culcita macrocarpa), and in spring flower buds (Ilex perado), fern sporangia (Osmunda regalis), fern fronds (Osmunda regaIis, Pteridium aquilinum) and moss tips. Fern fronds and moss tips are only taken when other foods are scarce. Native plants comprise the majority of the diet in August-September and April. In this month the species appears heavily dependent on flower buds of I. perado (with few or no alternative foods available). Seeds of C. arborea are ignored (presumably because they are too dry and indigestible) once flower buds reach a length of c2.8-3.0 mm. Seeds of other exotic species are very rarely consumed, especially C. japonica, because the species cannot extract the seed from its cone. Therefore, Azores Bullfinch may face food shortages in late winter, because I. perado is present at relatively low densities and most flower buds have already been consumed.
The laurel forest around the Pico da Vara summit (the stronghold of Azores Bullfinch) has been designated a Natural Forest Reserve by the Regional Government of the Azores. It was also designated a Special Protection Area by the Azorean Government under the EU Wild Birds Directive. The control of invasive exotics and planting of native species, raised in nurseries, began in early 1995 following the approval of a EU LIFE grant. The main aim of this project is to re-establish and improve the laurel forest, to ensure and maintain a viable population of Azores Bullfinch in the long term.
Hints for visitors
Azores Bullfinch is easiest to see in May-September, along the mountain road from Nordeste to Povoação, near Miradouro da Serra da Tronqueira; birds feed along this road and adjacent openings on seeds of herbaceous plants, especially P. capitatum (which forms a small carpet of pink flowers). In September- November it is possible, although more difficult, to see juveniles near Salto do Cavalo (above Furnas), and beyond Miradouro da Ponta da Madrugada, on the coast road from Nordeste to Povoação.
My work on Azores Bullfinch was financed by the Royal Society for the Protection of Birds (RSPB), with supervision from Prof. Chris Perrins and Dr Colin Bibby. The Forestry Service of the Azores in Nordeste provided logistic support and accommodation throughout the study. The University of the Azores and the county of Nordeste also supported the work. The LIFE project, which commenced 1995. is partially funded by the European Union.
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- Bibby, C. J., Burgess, N.D. and Hill, D.A. 1992. Bird Census Techniques. London, UK. Academic Press.
- Cabral, M., Magalhães, C., Oliveira, M. and Romão, C. 1990. Livro Vermelho dos Vertebrados de Portugal. Vol 1. Lisbon: SNPRCN.
- Godman, F. du C. 1866. Notes on the birds of the Azores. Ibis 5: 88-109.
- Groombridge, B. (ed) 1993. 1994 IUCN Red List of Threatened Animals. Gland & Cambridge, UK: IUCN.
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- Ramos, J.A. 1995. The diet of the Azores Bullfinch and floristic variation within its range. Biological Conserv. 71: 237-249.
- Ramos, J .A. 1996. Action plan for the Azores Bullfinch (Pyrrhula murina). In Heredia, B., Rose, L. and Painter, M. (eds) Globally Threatened Birds in Europe, Action Plans. Strasbourg: Council of Europe Publishing.
- Ramos, J.A. 1996. The introduction of exotic trees as a threat to the Azores Bullfinch population. J. Applied Ecol. 33: 710-722.
- Ramos, J.A. 1996. The influence of size, shape and phenolic content on the selection of winter foods by the Azores Bullfinch. J. Zook 238: 415-433.
- Ramos, J.A. 1998. Biometrics, weights, breeding and moulting seasons of passerines in an Azores cloud forest. Ringing and Migration 19: 17-23.
Instituto Politécnico de Bragança, Escola Superior Agrária, Quinta de Santa Apolónia, 5300 Bragança, Portugal.