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Luka Božič

Summary

In 2017, the International Waterbird Census (IWC) was carried out in Slovenia on January 14 and 15. Waterbirds were counted on all larger rivers, along the entire Slovenian Coastland and on most of the major standing waters in the country. During the census, in which 235 observers took part, 413 sections of the rivers and coastal sea with a total length of 1,427 km and 200 other localities (164 standing waters and 36 streams) were surveyed. The census was characterized by harsh winter conditions and high proportion of frozen water bodies. Altogether, 51,790 waterbirds of 61 species were counted. Thus, the number of waterbirds and the number of species recorded were close to the 21-year average. The highest numbers of waterbirds were counted in the Drava count area, i.e. 20,064 individuals (38.7% of all waterbirds in Slovenia). By far the most numerous species was Mallard Anas platyrhynchos (46.1% of all waterbirds), followed by Coot Fulica atra (6.8% of all waterbirds), Cormorant Phalacrocorax carbo (5.9% of all waterbirds), Black-headed Gull Chroicocephalus ridibundus (5.7% of all waterbirds) and Mute Swan Cygnus olor (3.9% of all waterbirds). The number of 1,000 counted individuals was also surpassed by Yellow-legged Gull Larus michahellis, Teal An. crecca, Tufted Duck Aythya fuligula, White-fronted Goose Anser albifrons, Pygmy Cormorant P. pygmeus and Grey Heron Ardea cinerea. Among the rarer recorded species, the Red-breasted Goose Branta ruficollis (registered for the first time during the January Waterbird Censuses and only for the third time ever in Slovenia) and Barnacle Goose Branta leucopsis (the first probable A category individual for IWC and Slovenia) deserve special mention. Numbers of the following species were the highest so far recorded during the IWC: Mandarin Duck Aix galericulata (together with 2006 and 2012), Pintail An. acuta, Ferruginous Duck Ay. nyroca, Long-tailed Duck Clangula hyemalis (together with 2003), Goosander Mergus merganser, Pygmy Cormorant, Herring Gull L. argentatus and Caspian Gull L. cachinnans. Number of Pochards Ay. ferina was the lowest so far recorded during the IWC.

Open access

Luka Božič

In 2015, the International Waterbird Census (IWC) was carried out in Slovenia on 17 and 18 Jan. Waterbirds were counted on all larger rivers, along the entire Slovenian Coastland and on most of the major standing waters in the country. During the census, in which 276 observers took part, 409 sections of the rivers and coastal sea with a total length of 1385.8 km and 224 other localities (172 standing waters and 52 streams) were surveyed. Altogether, 46,425 waterbirds of 57 species were counted. This is one of the lowest numbers of waterbirds recorded during the 19 years of IWC in Slovenia. The highest numbers of waterbirds were counted in the Drava count area, i.e. 17,014 individuals (36.7% of all waterbirds in Slovenia). By far the most numerous species was Mallard Anas platyrhynchos (45.9% of all waterbirds), followed by Coot Fulica atra (8.4% of all waterbirds), Blackheaded Gull Chroicocephalus ridibundus (7.5% of all waterbirds), Cormorant Phalacrocorax carbo (5.7% of all waterbirds) and Mute Swan Cygnus olor (4.6% of all waterbirds). The number of 1000 counted individuals was also surpassed by Tufted Duck Aythya fuligula, Yellow-legged Gull Larus michahellis and Teal An. crecca. Among the rarer recorded species, the Cattle Egret Bubulcus ibis (registered only for the third time during the IWC) and Lesser Black-backed Gull Larus fuscus (registered only for the fourth time during the IWC) deserve special mention. Also, Ruddy Shelduck Tadorna ferruginea was recorded for the fourth time during the IWC, but the individual observed was classified to category E (introduced species without self-sustaining populations, escapees from captivity). Numbers of the following species were the highest so far recorded during the IWC: Greylag Goose Anser anser, Muscovy Duck Cairina moschata, Shoveler An. clypeata, Goosander Mergus merganser and Common Sandpiper Actitis hypoleucos. The number of Redbreasted Mergansers M. serrator was the lowest so far recorded during the IWC.

Open access

Luka Božič

Abstract

In 2008, a coordinated census of Jackdaw Corvus monedula was carried out to assess breeding population, distribution and nest site selection in Slovenia. Data collection continued for unsurveyed areas in the 2009-2011 period, including information on former colonies and threats. A total of 663-794 Jackdaw pairs were recorded at 86 sites, while total Slovene breeding population was estimated to be in the range of 700-900 pairs. Over one third of pairs were recorded in Central Slovenia, notably the largest city Ljubljana (20.8%), followed by almost a quarter in the Podravje region. Most colonies numbered between 2 and 5 pairs, the largest occupying the Bežigrad district of Ljubljana (82-87 pairs). Large-scale density in geographically more or less uniform areas ranged from 3.65 pairs/10 km2 in the Sava plain to 0.15 pairs/10 km2 in mostly mountainous area in northern Slovenia. The majority of Jackdaws selected buildings for nesting (82.2% of pairs), while nesting in trees occurred less frequently (14.7%) and was almost entirely confined to the two easternmost regions of Slovenia. Nesting in cliffs was recorded at just two sites in Slovene Istria (3.1%). Average colony size differed significantly in relation to nest site type, with colonies in rock walls being on average the largest (median = 9.5 pairs), followed by colonies on buildings (6) and those in trees the smallest (3). Among pairs nesting on buildings, multi-storey residential buildings predominated (34.2%). A substantial percentage of population nested also on churches and tower blocks (14.4% and 13.5%, respectively). The highest percentage of pairs utilised holes in roofs (26.9%), followed by eaves (18.0%) and chimney pots (14.7%). Tree-nesting pairs occupied mostly small woods situated in open agricultural landscape. The most commonly used tree species was Beech Fagus sylvatica (53.1% of pairs) which hosted 14 of the total 16 forest colonies. For Jackdaws nesting in urban parks and avenues, plane trees Platanus sp. were the most important (30.6% of pairs). Their population stronghold was in lowlands, with 88.1% of pairs recorded at elevations under 400 m and the highest living colony in Slovenia at 578 m a.s.l. Jackdaws occurred on at least 54 specific sites in the past but became extinct there or declined severely by the time of this study. A minimum of 217-254 pairs were estimated lost at these sites, constituting a decline of 24% in c. 10-20 years. According to the IUCN criteria, Jackdaw would qualify as Vulnerable (VU) on the Red List of Slovenia. The commonest known cause of extinction/decline is renovation of buildings, a threat that is projected to escalate in the near future.

Open access

Luka Božič

Summary

In 2014, the International Waterbird Census (IWC) was carried out in Slovenia on 18 and 19 Jan. Waterbirds were counted on all larger rivers, along the entire Slovenian Coastland and on most of the major standing waters in the country. During the census, in which 268 observers took part, 413 sections of the rivers and coastal sea with a total length of 1395.1 km and 226 other localities (178 standing waters and 48 streams) were surveyed. Altogether, 45,346 waterbirds of 62 species were counted. This is the lowest number of waterbirds recorded after the 1997 and 1998 censuses. The greatest numbers of waterbirds were counted in the Drava count area, i.e. 20,217 individuals (44.6% of all waterbirds in Slovenia). By far the most numerous species was Mallard Anas platyrhynchos (43.0% of all waterbirds), followed by Black-headed Gull Chroicocephalus ridibundus (10.1% of all waterbirds), Coot Fulica atra (7.9% of all waterbirds), Yellow-legged Gull Larus michahellis (6.0% of all waterbirds) and Cormorant Phalacrocorax carbo (4.6% of all waterbirds). The number of 1,000 counted individuals was also surpassed by Mute Swan Cygnus olor, Pochard Aythya ferina, Tufted Duck Ay. fuligula and Teal An. crecca. Among the rarer recorded species, the Black Stork Ciconia nigra (registered for the first time during the January Waterbird Censuses; only the second winter record in Slovenia), Cattle Egret Bubulcus ibis and Flamingo Phoenicopterus roseus (both registered only for the second time during the IWC) should be given a special mention. Numbers of the following species were the highest so far recorded during the IWC: Shelduck Tadorna tadorna, Muscovy Duck Cairina moschata, Shoveler An. clypeata, Redthroated Loon Gavia stellata and Pygmy Cormorant Phalacrocorax pygmeus. Also, the total number of C and E category species/taxa was the highest to date, although still quite low with 70 individuals. Numbers of the following species were the lowest so far recorded during the IWC: Cormorant, Little Grebe Tachybaptus ruficollis and Green Sandpiper Tringa ochropus

Open access

Luka Božič and Damijan Denac

Številčnost in razširjenost izbranih gnezdilk struge reke Drave med Mariborom in Središčem ob Dravi (SV Slovenija) v letih 2006 in 2009 ter vzroki za zmanjšanje njihovih populacij

Open access

Dejan Bordjan and Luka Božič

Pojavljanje vodnih ptic in ujed na območju vodnega zadrževalnika Medvedce (Dravsko polje, SV Slovenija) v obdobju 2002-2008

Open access

Luka Božič, Matjaž Kerček and Dejan Bordjan

Naravovarstveno Vrednotenje Avifavne Območja Zadrževalnika Medvedce (SV Slovenija) in Dejavniki Ogrožanja