Blue rock-thrush (Monticola solitarius)
|Size||Length: 20 – 23 cm (2)|
|Weight||37 – 70 g (2)|
Classified as Least Concern (LC) on the IUCN Red List (1).
The blue rock-thrush is a small and attractive bird, named for the distinctive deep blue colouration of the male, which is slightly brighter around the eyes, head and throat, and darker and browner on the wings and tail. The female is duller, most often a brownish blue-grey above, streaked buff and brown on the lower parts of the face and upper chest, with buff-brown barring on the lower breast and undertail (2) (3). The juvenile is dark brown, lacking any blue tone to the plumage, and is more strongly spotted and scaled than the female. The five subspecies of the blue rock-thrush exhibit a gradual change in appearance across the species’ range; some races are much smaller and duller, and may be paler blue-grey, while others may be darker, or show slight variation on the patterning of the underparts (2). The subspecies Monticola solitarius philippensis is the most different in appearance, being stronger blue above, with a rich reddish-brown breast and undertail, and indistinct buff and black narrow barring over the body (2) (4).
The blue rock-thrush is a widespread species, with breeding and non-breeding populations spanning from North West Africa, throughout Southern Europe (including Italy, the Balkans, Greece and Turkey), the Arabian Peninsula, northern India and the central Himalayas to China, Mongolia, Japan and South East Asia (2) (5).
The blue rock-thrush breeds mainly on cliffs, in rocky valleys and gorges, on crags, outcrops, sea cliffs and rocky coasts. It also breeds occasionally in ruins, quarries, isolated stone buildings and on houses, churches, castles and monuments. Depending on the location and the subspecies, the blue rock-thrush can be found from sea level up to elevations of 4,200 metres. Wintering habitat is more varied; however, it is still often associated with areas of bare rock, and includes foothills, valleys, towns, olive groves and gardens, areas of woody vegetation on rocky slopes and isolated hills in rainforest and savannah (2).
The blue rock-thrush feeds on a wide variety of prey species, including invertebrates such as grasshoppers, locusts, crickets, beetles, spiders, snails and earthworms, and, despite its small size, small vertebrates such as geckos, snakes, frogs and mice. During the winter, the blue rock-thrush will also take fruits, berries and seeds. It forages by scanning the ground from an elevated vantage point where it sits alone, dropping to the ground when a suitable prey item is spotted. It also spends some of its time hopping and running on the ground in search of prey, and may occasionally catch small insects on the wing (2) (5).
Because of the wide ranging distribution of the blue rock-thrush, different populations and subspecies breed at different times. In general, the breeding period lasts for around two to three months, beginning in some parts of the range as early as January, although more often between April and May, and finishing in all areas by July (2). The blue rock-thrush builds a loosely constructed, shallow cup-like nest of coarse dry grass, moss and leaves, which is lined with soft grass, feathers and plant down. It is usually placed around two to five metres off the ground, under overhanging rocks or in crevices on cliffs. The female blue rock-thrush lays between 3 and 6 eggs in a clutch, which hatch after an incubation period of 12 to 15 days. The young chicks remain in the nest for around 15 to 18 days, and remain dependent on the adult for around two weeks after fledging (2).
Although the blue rock-thrush population is generally considered stable, in some areas local populations have demonstrated significant declines as a result of coastal development, flooding of canyons and gorges for the construction of reservoirs, and regeneration projects which restore old towers and churches (2).
The blue rock-thrush is not globally threatened, and there are no known specific conservation measures targeted at this species.
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- Incubation: the act of incubating eggs, that is, keeping them warm so that development is possible.
- Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones), echinoderms, and others.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
- Vertebrates: animals with a backbone, including mammals, birds, reptiles, amphibians and fish.
IUCN Red List (September, 2010)
- del Hoyo, J., Elliot, A. and Sargatal, J. (2006) Handbook of Birds of the World. Volume 11: Old World Flycatchers to Old World Warblers. Lynx Edicions, Barcelona.
Identification Atlas of Aragon’s Birds – Blue rock thrush (September, 2010)
- Zuccon, D. and Ericson, P.G.P. (in press) The Monticola rock-thrushes: phylogeny and biogeography revisited. Molecular Phylogenetics and Evolution.
- Outlaw, R.K., Voelker, G. and Outlaw, D.C. (2007) Molecular systematics and historical biogeography of the rock-thrushes (Muscicapidae: Monticola). The Auk, 124(2): 561–577.