Blue rock thrush
The blue rock thrush is a species of chat. This thrush-like Old World flycatcher was formerly placed in the family Turdidae. It breeds in southern Europe, northwest Africa, and from Central Asia to northern China and Malaysia. The blue rock thrush is the official national bird of Malta.
Taxonomy
The blue rock thrush was described by Carl Linnaeus in 1758 in the 10th edition of his Systema Naturae under the binomial name Turdus solitarius. The type locality is Italy. The scientific name is from Latin. Monticola is from mons, montis "mountain", and colere, "to dwell", and the specific epithet solitarius means "solitary".The rock thrush genus Monticola was formerly placed in the family Turdidae but molecular phylogenetic studies have shown that the species in the genus are more closely related to members of the Old World flycatcher family Muscicapidae.
There are five recognised subspecies:
- M. s. solitarius – northwest Africa, south Europe, north Turkey to Georgia and Azerbaijan.
- M. s. longirostris – Greece and west and south Turkey through the Middle East to the northwest Himalayas to northeast Africa and India
- M. s. pandoo – central Himalayas to east China and north Vietnam to Greater Sunda Islands
- M. s. philippensis – east Mongolia to Sakhalin south to Japan, extreme north Philippines and northeast China to Indonesia
- M. s. madoci Chasen, 1940 – Malay Peninsula and north Sumatra
Description
The blue rock thrush is a starling-sized bird, in length with a long slim bill. The breeding male of the nominate subspecies is unmistakable, with all blue-grey plumage apart from its darker wings. Females and immatures are much less striking, with dark brown upperparts, and paler brown scaly underparts. The male of the subspecies M. s. philippensis has rufous-chestnut plumage from the mid-breast down to the undertail. Both sexes lack the reddish outer tail feathers of rock thrush.Vocalizations
The male blue rock thrush sings a clear, melodious call that is similar to, but louder than, the call of the rock thrush.The Europe and Asia groups both have a "short song and a long song, consisting of similar melodious whistles, trills and more burry notes." Generally, the vocalizations are similar in both groups. Basic sound traits generally overlap, such as phrase duration, note length, and min./max. frequency. Several notes are identical. The long song is a bit more common in the Asia group. Among populations in Indonesia, there are four basic calls. "The fundamental call frequency appeared to be concentrated around 1.6 kHz, but weak components of the spectrum reached to approximately 4 kHz. The structure of the four call types was quite different: 1) the shape of the spectra differed considerably; 2) the frequency of maximum sound energy was between 1.2 and 1.8 kHz; 3) the duration of the calls varied between 200 and 1500 ms; 4) the-10dB bandwidth was in the range between 900 Hz and 1300 Hz."
Similar species
Monticola is a monophyletic clade as all member species share a common ancestor. M. solitarius are especially similar to: Blue-capped rock thrush, Chestnut-bellied Rock Thrush, Common rock thrush-also known as Rufous-tailed rock thrush, Little rock thrush, and White-throated rock thrush.Distribution and habitat
The European, north African and southeast Asian birds are mainly resident, apart from altitudinal movements. Other Asian populations are more migratory, wintering in sub-Saharan Africa, India and southeast Asia. This bird is a very uncommon visitor to northern and western Europe. There is some overlap in breeding and wintering ranges with the common rock thrush ; Palearctic and southwestern Asia for breeding and northern Africa for wintering. It is known to have been spotted in North America twice: once in British Columbia in 1997 and once in Oregon and the Farallon Islands in 2024. It is unclear whether the Oregon and Farallon Islands spottings were the same bird. It is highly unlikely that the British Columbia sighting was the same individual bird as the Orgegon/Farallon Islands sighting as the blue rock thrush typically lives 5-10 years in the wild.Choi, et al., conducted a study of blue rock thrush population on Hongdo Island, South Korea from 2005-2009. The species arrives in spring and disappeared in autumn, indicating that the Hongdo population is migratory rather than resident. Breeding density was estimated at about 8 breeding pairs per km², and individual territories averaged about 2.87 hectares. The species showed a strong preference for rocky cliffs for their homes, especially exposed rock faces. They concluded habitat structure was more important than food availabity.
In the first confirmed case of successful urban nesit by M. solitarius, Rouibi, et al., conducted a study of M. solitarius in El Bouni, Algeria over three breeding seasons from 2016- 2018. They found the species made a nest beneath the roof of a residential building, which is very different from its usual rocky cliffs, escarpments, and coastal outcrops. Pairs have also been found living in urban areas in Malta.