Hirundo 2/2001

Elts, J.
Counts of winter land birds in Estonia, 1987/88–1998/98
Summary: The paper summarizes the methods and results of the winter land bird census in Estonia. The census is carried out on transects of unlimited width during three seasons (autumn count between 15 and 28 November, Christmas count between 25 December and 7 January, spring count between 15 and 28 February). In the first years of the project, up to 180 census reports were sent; the number dropped below 100 in the mid-1990s, but is currently increasing again. Most of the transects have been counted in only one winter; 18% of transects have been used in at least five, and 5% of transects in at least ten years. Data analysis indicates that the optimal transect length for Estonian conditions is 8–12 km (see Fig. 5). Numbers of detected birds have been highest in rubbish areas (16.2±6.5 ind. per km of transect, not corrected for visibility), and lowest (less than 1 ind. per. km) in forests, clearcuts, shrub areas and open landscapes. The numbers of 15% of species (out of 48 studied) declined strongly during the winter; in 44% the decline was moderate, in 25% the numbers were stable, and in 17% there was a moderate increase (Fig. 8). Long-term trend was decreasing in seven species out of ten studied (the most abundant species; Fig. 9). The declines were significant in Parus montanus and Pica pica. During the 12 years, the numbers of Pyrrhula pyrrhula increased most, due to the high abundance in the last two winters.

Leito, A. & Ojaste, I.
Migration routes of the Common Cranes breeding in Estonia: first results of colour-marking and radio- and satellite-tracking
Summary: Between 1990 and 2001, 52 Common Cranes (Grus grus) have been colour-ringed in seven Estonian counties. Additionally, radio-transmitters have been attached to eleven birds and satellite transmitters to four. There are altogether 169 recoveries of 26 individuals from eight countries, including 76 recoveries of 20 individuals outside Estonia. The largest numbers of foreign recoveries come from Germany (36 recoveries / 10 individuals), followed by Spain (24 / 6), Hungary (6 / 5), Sweden (3 / 3), France (2 / 2), Poland (3 / 1) and Kaliningrad region in Russia (1 / 1). Forty recoveries of 16 cranes have been made during autumn migration, 21 recoveries of 7 individuals during spring migration, and 15 recoveries of seven birds during winter (see Table 2).
The cranes, grown up in Estonia, use both the western and the eastern migration route (share of recoveries 3:1). So far, only Spain has been identified as wintering area. The marking results indicate that the Estonian and Finnish cranes use similar migration routes and directions, and that the primary migration direction and exact routes are not strictly (genetically) determined. The direction of primary migration of the Estonian and Finnish cranes is between ca. 180°–225°. The western and eastern migration routes as well as the area between them, may be treated as one migration range, where there are no significant movement barriers for birds of the same population. The Estonian (breeding) crane population is an open part of a larger, relatively homogeneous population, which breeding distribution covers at least Estonia and Finland, or (more probably) the whole western part of the range of the species in Europe, reaching Ukraine, Byelorussia and northwestern Russia in the east.

Tuule, E., Tuule, A. & Lõhmus, A.
Numbers of raptors and owls in the surroundings of Saue, 1961–2000
Summary: Since the late 1980s, the numbers of raptors and owls have been monitored in several study plots in Estonia, but earlier data are very scarce. This paper summarizes a 40-year (1961–2000) study in the surroundings of Saue, North Estonia (59°18’N, 24°34’E). The study area is dominated by forests and agricultural habitats, and encompasses 60 km². Its habitat composition has significantly changed during the study (Table 1), especially with respect to seminatural meadows (10.4% in 1961, 0.3% in 1996), wooded meadows (31.5% and 23.4%) and cultivated land (26.2% and 38.3%).
Breeding territories of raptors and owls were mapped according to their territorial behaviour, repeated observations, nests or fledglings. The amount of fieldwork has been generally sufficient (over 200 hours annually) but variable. Despite only a weak correlation (R²=0.09, p=0.06; Fig. 1) between the annual numbers of observation days and territories, the count results have been averaged by four-year periods to establish trends for individual species.
Altogether, 17 species (7 Accipitriformes, 3 falcons, 7 owls) were found as breeders. Their total density (on average 48.2 territories per 100 km²) did not change during the 40 years (R²=0.02, p=0.37; Fig. 2A). In contrast, both the number of breeding species and Pianka’s diversity index decreased significantly between 1961 and 2001 (rs= -0.56, p<0.05, and R²=0.31, p<0.001, respectively; Fig. 2B). Significant negative changes took place in six species (Falco columbarius and Asio flammeus disappeared; the numbers declined in Circus cyaneus, Falco tinnunculus, F. subbuteo and Bubo bubo), while positive changes occurred in only three (Circus pygargus settled to the area; the numbers of Accipiter gentilis and Strix uralensis increased; Table 2). The total numbers of vole-specialized raptors and owls fluctuated annually (peaks in 1965, 1977, 1983, 1991 and 1996) but with no significant periodicity (Fig. 3).
Additional 14 species (8 Accipitriformes, 3 falcons, 3 owls) were recorded only as passage migrants or vagrants. The most frequent non-breeders were Buteo lagopus, Aquila chrysa?tos and Falco peregrinus, while five species (Milvus milvus, Circus aeruginosus, Falco rusticolus, Surnia ulula and Strix nebulosa) have been observed just once. The total number of observations of passage migrants and vagrants has decreased during the study (in the 1960s 49, in the 1970s 49, in the 1980s 15, and in the 1990s 11 obs.).
The changes of habitat composition of the study area are generally typical to Estonia and the trends of several species in Saue match with those found or suggested in Estonia as a whole. The most remarkable exception is the stable or even increasing breeding population of Strix aluco, which has been mostly considered as declining. The difference may be caused by the preserved rural landscape mosaic in Saue; elsewhere the habitat has often become forested or urbanized. The data about general changes in the raptor and owl community have no clear parallels with the few previous reports or notes from Estonia.

Lõhmus, A. & Sellis, U.
Foraging habitats of the Black Stork in Estonia
Summary: According to casual observations in the 1990s, the main foraging habitats of the Black Stork (Ciconia nigra) in Estonia were waterbodies (87.8% of the total of 82 foraging sites), especially rivers, streams and ditches (63.4% of sites). The sites were often situated near roads and even farms, but were usually shaded by forest cover. The Storks foraged on average 3.6±0.8 km (range 0.7–5.9 km) from known nests, but this value is likely an underestimate. Lowered quality of foraging habitats due to forest drainage may be one of the reasons of the decrease of the species in Estonia.

Bird conservation news
Kose, M. Project ‘Nest boxes for European Roller’

EOS chronicle and news