Common Swifts (Apus apus) in the Baikal area
In "Cisbaikalia" (the catchment area of the Angara River west of Lake Baikal, covered mainly by the Irkutsk Region) the subspecies A. a. pekinensis to be found mainly from the Baikal area eastwards is presumed to be intergrading with the nominate subspecies A. a. apus found mainly to the west (Stepanyan 1990). Gagina (1988) reports A. a. apus as nesting in the Baikal region, including the valleys of Verkhnaya Angara and the Barguzin rivers in Transbaikalia, while for the area of the Selenga River he reports nesting of A. a. pekinensis. Stepanyan (1990) on the other hand records that A. a. pekinensis does occur east of Baikal, including the area of Verkhnaya Angara, while A. a. apus is not present there.
East of Baikal, nesting has been confirmed in the Temnik River valley, in the Khamar-Daban mountain range, SE of southern Baikal, but this species is uncommon in contrast to the abundant Pacific Swift A. pacificus (Vasil'chenko 1987).
On the north-east shore of Baikal, in Barguzinski Zapovednik, the Common Swift is a rare migrant (Ananin 2001). In the upper Chara hollow (Verkhne-Charskaya hollow, Chita Region, north-east of Baikal), it is very rare (Tolchin, Pyzhjanov 1979); this is near to the north-eastern margin of its nesting range, an area which includes the Olyokma River and the Nerchinsky mountain range (Stepanyan 1990). It is also recorded nesting widely in Buryatia and generally in all the water catchment area of Lake Baikal (Bold et al., 1991).
There are some details on Common Swifts dates and nesting preferences in more studied areas as described below.
In the southern Irkutsk Region, A. apus is a common breeding species at least in the steppe region known as Zima-Kuytun [Ziminsko-Kuytunsky] (ca 54o N, 102o E), an extreme western fragment of the Angara forest-steppe (Mel'nikov 1999 a, b; Fefelov, 1999). Here it prefers to nest in tree cavities in river valleys. For example, it is very common in pine and larch forests at high altitudes. However, I have a record of its nesting in a brick water-tower in the Kuytun District. The Pacific Swift is equally common here as well, but unlike A. apus, A. pacificus breeds much more often in settlements, as well as in cavities in cliffs and trees. From my personal observation, I can confirm that the first records of A. apus are on 21 May 1976, 17 May 1977, 21 May 1979, 20 May 1980, 21 May 1981, 23 May 1991 (Uyan, Kuytun district). Latest dates records in the same locality are: 19 August 1977, 20 August 1981, 15 August 1982, 10 August 1984, 15 August 1983, 20 August 1996; the latest date, 14 September 1976, is exceptional and could be related to late birds on passage. The Common Swift does not arrive as early as the Pacific Swift (for example, in 2000, the latter species arrived on 13 May), but generally their dates of arrival and departure are similar, being closely connected with weather conditions and the availability of food (flying insects). On migration, both species are often mixed. It is very difficult to count the individuals of each species, because they look alike from below. Some A. apus in a large flock of A. pacificus and vice versa can not be differentiated for certain.
In the southern part of the Irkutsk Region (ca 52o N, 104o E), including Irkutsk, both Common and Pacific Swifts occur. As far as breeding in the city of Irkutsk in houses and other buildings is concerned, the Pacific Swift is predominant. In 1976-1982, Common Swifts arrived between 17 and 20 May, while Pacific Swifts arrived between 13 and 20 May (G. Maximova 1982, in litt.). A big flock of Common Swifts with a single Pacific Swift were seen in Irkutsk on 12 May 2002, after a strong north-west wind on the previous day, which might have assisted their earlier arrival.
Our observations in the delta of the Selenga River (ca 52o N, 107o E) suggest that the Common Swift is not numerous, but it is probable that they breed in the Selenga delta. It is recorded in May and June in groups of 10-15 individuals flying over, often in flocks together with the more numerous Pacific Swifts (Fefelov et al., 2001). Postbreeding records are also available (Zhuravlyov 1995). In this area, it is believed to nest presumed in trees in forests around the delta, and might also nest in buildings such as water-towers etc. However, the Pacific Swift is much more common here, especially breeding in settlements. During the course of my work in the Selenga delta between 1986 and 2002, I observed Common Swifts three times between 28 May (1991) and 22 June (1993), where it occurred in flocks of up to 15 individuals. Apart from this, there is a record from N. Groen and R. Mes (Netherlands), who worked with us on Black-tailed Godwit Limosa limosa in the delta from 25 May to 15 June 2002, of two birds flying on 26 May and two on 6 June.
Bold A., Dorzhiev Ts.Z., Yumov B.O., Tsevenmyadag N. 1991. [Bird fauna of Lake Baikal water catchment]. In: Tsyrenov V.Zh. (ed.) Ecology and fauna of birds of Eastern Siberia. Ulan-Ude: Buryat Science Center of Russian Academy of Sciences, p. 3-24. (In Russian)
Fefelov I.V. 1999. [Addition to the list of birds of the Ziminsko-Kuytunsky steppe territory, Eastern Siberia]. Russian J. Ornith. Express-issue 69: 3-5. (In Russian)
Fefelov, I.V., Tupitsyn, I.I., Podkovyrov, V.A. & Zhuravlyov, V.E. 2001. [The birds of the Selenga delta: Faunal summary]. Irkutsk, East Siberian Publ. Comp. (In Russian)
Gagina T.N. 1988. [Checklist of birds of Lake Baikal water catchment area]. In: Skryabin N.G. (ed.) Ecology of terrestrial vertebrates of Eastern Siberia. Irkutsk, Irkutsk Univ. Publ.: 85-123. (In Russian)
Mel'nikov Yu.I. 1999a. [Birds of the Ziminsko-Kuytunsky steppe territory, Eastern Siberia. Part 1. Non-Passeriformes]. Russian J. Ornith. Express-issue 60: 3-14. (In Russian.)
Mel'nikov Yu.I. 1999b. [Birds of the Ziminsko-Kuytunsky steppe territory, Eastern Siberia. Part 2. Passeriformes]. Russian J. Ornith. Express-issue 61: 3-13. (In Russian.)
Stepanyan L.S. 1990. [Conspectus of the ornithological fauna of the USSR]. Moscow, Nauka. (In Russian)
Tolchin V.A., Pyzhjanov S.V. 1979. [Bird fauna of Verkhne-Charskaya hollow, and its zoogeographical analysis]. In: Belov A.V., Lyamkin V.F. (eds.) Questions on zoogeography of Siberia. Irkutsk, Institute of Geography of Siberia and Far East of Siberian Branch of Russian Academy of Sciences, p. 3-33. (In Russian)
Vasil'chenko A.A. 1987. [Birds of the Khamar-Daban Mountains]. Novosibirsk, Nauka. (In Russian)
Zhuravlyov V.E. 1995. [Passerines of the Selenga delta (with a complete bird list)]. Irkutsk. Deposited in VINITI Center, Moscow, 30.06.1995, No. 1937-В 95. (In Russian)
© APUSlife 2004, No. 2942