Pastor roseus - movimentações

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Pastor roseus - movimentações

Mensagem por Gonçalo Elias em Sab Jun 16, 2018 9:32 am

Considerando o recente influxo de Pastor roseus que atingiu a Europa nas últimas semanas, parece-me oportuno disponibilizar aqui alguma informação adicional sobre os movimentos desta espécie.

Anexo informação retirada do "Cramp". Este volume foi publicado em 1994, pelo que não contém informação mais recente, mas já dá para ficar com uma ideia sobre datas, padrões e amplitudes. Marquei a negrito as frases que têm mais directamente a ver com a Europa.


Taken from the BWP on CD-ROM: copyright Oxford University Press.

Movements

Migratory, wintering south-east of breeding range in peninsular India and Sri Lanka; migrates in flocks (sometimes huge) by day. Populations from west of range migrate almost directly east before heading south-east into India.

In India, widespread in winter east to Bihar and south throughout peninsula; abundant in Gujarat and Deccan, with fewer further south in Kerala and southern Tamil Nadu. In Sri Lanka, winters mainly in north and in coastal dry zone; sometimes common, at other times rare or absent. Straggles east to Bangladesh and Assam; vagrant or irregular visitor to Andaman Islands. Regular in southern Sind (Pakistan). Also winters in small and irregular numbers in Oman. (Henry 1971; Ali and Ripley 1972; Gallagher and Woodcock 1980; Roberts 1992).

Autumn migration less well described than more synchronized and spectacular spring return. After young leave nest, adults and young desert colony rapidly (see Breeding) and move together to areas of abundant food, but age-groups soon separate (Schenk 1907; Korelov et al. 1974); during this post-breeding or summer dispersal phase, flocks roam widely (Kovshar' 1966), and may be nomadic (Isakov and Vorobiev 1940; Kazakov 1976). In Uzbekistan, birds (including a ringed individual) flew north-west from breeding colony to vineyards c. 50 km away; also reported remaining in vineyards for 2- months (Serebrennikov 1931), so they may not resort to nomadism in summer if food remains abundant. Summer dispersal changes almost imperceptibly into directional autumn migration (Ivanov 1969) in which adults leave before juveniles (Hüe and Etchécopar 1970; Korelov et al. 1974). Departure of birds on autumn migration usually noticed as diminution of numbers (Schenk 1934), but mass departures do occur (Serebrennikov 1931; Salikhbaev and Bogdanov 1967). Reported leaving in flocks of 4–6 birds, departure of such flocks lasting at least 2 hrs (Schenk 1934). Birds from east Mediterranean migrate chiefly east, and birds from south-central Asia predominantly south-east; all populations pass through Pakistan on narrow front between foot of Himalayas and Baluchistan, thereafter dispersing more widely over peninsular India (Abdulali 1947).

Spring route is reverse of autumn. Many birds pass through Afghanistan; some continue through northern and western Iran and Iraq (Hüe and Etchécopar 1970; D A Scott); others head for south-central Asia; north-easterly migration recorded in Uzbekistan (Salikhbaev and Bogdanov 1967) and at Alma-Ata (Kazakhstan) (Korelov et al. 1974), birds having migrated to west of Pamirs (Ivanov 1969). In Turkmeniya, migrates mainly north-west along Amu-Dar'ya, Murgab, and Tedzhen rivers, continuing to Caspian or to Atek and Akhal plains (Rustamov 1958). Pre-migratory fat deposited in India in spring (George 1976), but no information on timing. Spring migration chiefly 08•30–11•00 hrs in small parties or flocks varying in size from tens to thousands; millions can pass in a few days (Serebrennikov 1931; Dementiev and Gladkov 1954; Rustamov 1958; Ali and Ripley 1972).

Summer dispersal starts as soon as most young have fledged. In Uzbekistan, 1929, young fledged mid-June, and adults and young moved to vineyards, remaining there until main departure on 25 August (Serebrennikov 1931); more frequently, main departure from Uzbekistan mid-September, few birds remaining to October (Salikhbaev and Bogdanov 1967). Further north, in Kazakhstan, most leave by late August, with few remaining to mid-September (Korelov et al. 1974). In Hungary and Greece, where breeds only during sporadic influxes, departure July–August, shortly after young leave nest (Schenk 1907, Schenk 1934; Hölzinger 1992c). Main passage (sometimes abundant) in southern Caspian area August and early September (Passburg 1959; Feeny et al. 1968; D A Scott). In Afghanistan, movement recorded early July to mid-October, with adults preceding juveniles (Paludan 1959). One of earliest migrants to reach India; passage through Pakistan and north-west India begins early July, peaks late July, and ends chiefly in September; further south in peninsular India, arrival late September to November. Winter occurrence and timing in India probably influenced by flowering of nectar-bearing trees and fruiting of figs Ficus, etc. (Abdulali 1947).

Spring migration begins in March, with large-scale passage through north-west India and Pakistan March–April, and through Afghanistan April–May (Ali and Ripley 1972). In Iran, movement last week of April to 3rd week of May (D A Scott); recorded mostly mid-May in Iraq (Marchant 1963a), and passage records in Syria and Turkey chiefly in May (Beaman 1986; Baumgart and Stephan 1987). One of latest migrants to reach breeding areas, with arrival in Uzbekistan and Turkmenistan mid-April to May (Rustamov 1958; Salikhbaev and Bogdanov 1967), and in Kazakhstan usually mid- or late May, somewhat earlier in south (Kovshar' 1966; Korelov et al. 1974). In Greece, 1980–8, arrived 2nd half of May (Hölzinger 1992c); reached Hungary in early June in 1907 and 1932 invasions (Schenk 1907, Schenk 1934). 1 ringing recovery: bird ringed north-east Hungary, June, recovered c. 4800 km south-east in western Pakistan the following April (Ali and Ripley 1972).

In line with irregular colonization (see Social Pattern and Behaviour), spring invasions occur west of normal range in south-east Europe (notably to Yugoslavia and Greece), apparently less frequent and smaller than formerly; similarly, at edge of breeding range, numbers may vary from thousands to few (e.g. in Hungary). At Villafranca in north-east Italy, 6000–7000 pairs bred in exceptional influx in 1875; but in 20th century only vagrant to Italy. (Ferguson-Lees 1971.) At Petrovac (coast of south-east Yugoslavia), several thousand recorded in late May 1989 (Axell 1989).

Further north in Europe, vagrant both seasons (see Distribution, also Alström and Colston Alström and Colston 1991). In Britain and Ireland, 160 records before 1958, and 211 in 1958–91, chiefly mid-May to beginning of November; widely distributed, with many in Shetland (Scotland), chiefly May–July, and in Isles of Scilly, chiefly October; 4 records of successful overwintering (Dymond et al. 1989; Rogers and Rarities Committee 1991, Rogers and Rarities Committee 1992). In Sweden, recorded mostly May–June (Breife et al. 1990). In France, 1900–89, 28 records involving 62 individuals, mainly in west and south; one overwintering record (Dubois and Yésou 1992).
Bird wintered on Frégate Island (Seychelles), October 1990 to February 1991 (A Gretton).
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Gonçalo Elias

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