Hirundo 1/2001

Kose, M.
The Barn Swallow – Bird of the Year 2000
Summary: In 2000, the Barn Swallow (Hirundo rustica) was the Bird of the Year in Estonia. In this paper, the results of the campaign and relevant monitoring projects are presented. The spring arrival of the species was recorded in 25 sites; the first individual was recorded on 15 April. In the monitoring project “Swallows of Home Neighbourhood” (started in 1993) 206 observers all over Estonia participated in 2000. The results of the monitoring project showed a 15% increase in 2000 compared to 1999. In general, the numbers are fluctuating with no significant trend (Fig. 1). The average brood size (4.26) was lower than the long-term average (4.40). Young Barn Swallows fledged on average on 11 July, which is almost the same as in the long term (12 July). According to special questionnaires, the trends in the two latest decades and the importance of different limiting factors are analysed (Figs. 3-4).

Pehlak, H., Luigujõe, L. & Kuresoo, A.
Midwinter waterfowl census in the coastal waters of Estonia, 1994-1999
Summary: In Estonia, midwinter waterfowl censuses were introduced in 1960; now the project is included in the State Environmental Monitoring Scheme. The paper gives an overview about the methods and summarizes the results about species composition, distribution and numbers of wintering waterfowl in the coastal waters of Estonia in 1994-1999. Out of a total of 199 census sites, 134 were surveyed in at least one winter; and more than one hundred people sent their observations annually. Altogether, 35 waterbird species were observed, among which 18 species were recorded every year and five additional species in more than three years (Table 2). Six species occurred in only one winter. Distribution of the most common wintering species is presented on maps (Figs. 4-12).
The importance of each site for wintering waterfowl was assessed as a sum of median numbers of every species on the site divided by their Ramsar criterion 3c value (the threshold numbers of at least 1% of the biogeographical population of the species). According to this, the most important coastal wintering sites are situated on the northwestern coast of Saaremaa Island and the western coast of the Sõrve Peninsula. Valuable sites can also be found on the coasts of Hiiumaa Island as well as the northern coast of mainland Estonia (Fig. 13). Most of the important wintering sites are covered by protected areas or IBAs (Table 3).

Lõhmus, A.
Selection of foraging habitats by birds of prey in north-western Tartumaa
Summary: Only scarce data exist about the foraging habitats of raptors and owls in Estonia. In this paper, the results of regular field observations in 1993-2000 (for the rarest species also from 1991-92) are presented about habitat use and interspecific differences, habitat selection (as revealed from comparisons with available habitat distribution) and relative selectivity of different species. The study area (900 km²) was situated near Tartu, east-central Estonia. Habitat availability was determined by describing 1800 random plots in the field in 1997-2000. Habitat use was measured as the number of observations, defining an observation as one individual in a habitat type at one encounter. The activity of birds was classified as confirmed or probable foraging (bird attacking or following prey, hovering or perching) and possible foraging (flying). Among the total of 1480 observations, five species out of 21 were represented with less than five observations and were omitted from analyses. Habitat selection was measured with the selection coefficient: SKi=log10 (pi / Pi +1), where i is habitat type, p its relative frequency among foraging observations, and P is the proportion of the habitat type in the study area (Gorman & Reynolds 1993). The general selectivity of a species was measured in cluster analysis as the euclidean distance (UPGMA algorithm) between the habitat composition of the study area and of the foraging observations of that species.
Habitat use of the 16 species is presented in Appendix. Pernis apivorus was among the species most often foraging in forest. It avoided cereal crops and other cultivated or man-made habitats. Haliaeetus albicilla used most often (and also preferred) waterbodies as well as flood-plain meadows. Circus cyaneus and C. pygargus preferred cereal fields (both in use and temporarily set-aside) and meadows; the latter species also flood-plain meadows. Circus aeruginosus preferred also open flood-plain meadows, other meadows and cereal fields. The main foraging habitat for Accipiter gentilis and A. nisus was forest; in winter, the latter species was the only raptor regularly hunting in settlements. Buteo buteo characteristically preferred forest openings (forest rides and roads as well as clear-cut areas), but extensively used also meadows and cereal fields. Both Aquila pomarina and A. clanga selected for open flood-plain meadows and other meadows; the first species also for set-aside cereal fields. Mires were the most important foraging habitat for Aquila chrysaetos, and cereal fields for Falco tinnunculus and migrating Buteo lagopus. Falco subbuteo made its foraging flights mostly over forests and flood-plain meadows, while Pandion haliaetus hunted only at waterbodies (incl. over flooded areas). According to visual observations, Strix uralensis mostly hunted from perches (95% of obs.), preferring meadows, forest rides and roads as well as clear-cut areas. The species occurred often near houses, but rarely hunted on flood-plain meadows or mires.
Interspecific differences in habitat use are presented on Fig. 1. According to confirmed or probable foraging cases, the cluster of species feeding mostly upon small mammals was distinct. These species used mostly open agricultural landscape and flood-plain meadows for hunting, whereas other species avoided e. g. cultivated meadows and cereal fields. Seasonal differences in foraging habitat use were small at least in the first species group, with cereal fields having slightly more important role in early spring and autumn than during the summer (contrarily to natural habitats; Fig. 4). This pattern could be explained by changing accessibility of prey due to snow or vegetation.
Foraging habitat use was most similar in the following species-pairs: 1) Accipiter gentilis and Pernis apivorus (mostly forest-dwelling, avoiding cereal fields); 2) the two spotted eagle species (foraging mainly on flood-plains and other meadows); 3) Circus cyaneus and C. pygargus (mostly using meadows, fields, bushy flood-plains and mires with trees); 4) Falco tinnunculus and Buteo lagopus (using mainly cereal fields). As the first species have very different diet composition and the latter are rare, the two spotted eagles and the two harrier species can be considered as potentially competing for hunting sites in the study area.
In preferred habitats the hunting of raptors was more successful (p=0.003). This reveals to the sensitivity of birds of prey to landscape changes, especial-ly in rare species, which were found to be more selective (Fig. 2). However, the population dynamics of the studied raptor community during the 20th century did not correspond to the trends expected by changes in the coverage of different habitat types. This can be due to confounding effects of other factors (e. g. persecution, pesticides, and availability of nest sites).

Väli, Ü.
Quarries as waterfowl habitat in Hiiumaa
Summary: In 1996-1999 the species composition and numbers of waterfowl were studied in six small gravel quarries with permanent water bodies in southern Hiiumaa. 19 species were registered (including seven confirmed breeders, eight probable breeders and four possible breeders; table 2). Charadriiformes were represented with 9 species, followed by Anseriformes (7), Gruiformes (2) and Podicipediformes (1). Several coastal birds were also recorded to breed in quarries. Closely situated quarries formed one habitat unit for Podiceps auritus and Larus canus. I found no statistically significant relation between quarry characteristics and bird numbers. However, the more diverse bird communities occurred in quarries with more irregular shape (p=0.027).

Edula, E.
Relative numbers of passerines in the surroundings of Viljandi, 1996-2000
Summary: In the surroundings of Viljandi, relative numbers of 38 passerine species were assessed by the number of found nests during 1996–2000, comparing the results with those from 1956–1995 (Edula 1998). In the last five years, the numbers of discovered Tree Pipit and Whinchat nests dropped strikingly. There were no signs of recovery in the Marsh Tit, Willow Tit and Crested Tit as well as the Starling and Linnet populations. Wood Warblers still followed their long-term downhill. Comparatively many Dunnock, Garden Warbler and Pied Wagtail nests were found; and Blackbird and Robin populations still continued to increase.

Notes
Lõhmus, A.
How accurate are the density estimates fo forest-dwelling raptors?
Nellis, R., Nellis,R. & Nellis,V.
Common Cranes wintering in Saaremaa
Tammekänd, I.
Wintering Reed Buntings in Pärnu

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