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  • Author: Antun Žuljević x
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Nest-site characteristics and breeding density of Magpie Pica pica in Sombor (NW Serbia)

In March 2009, active Magpie Pica pica nests were censused in the town of Sombor (Vojvodina, NW Serbia) to study nest-site characteristics, breeding density and spatial distribution. The area of the town can be divided into two parts according to different urban landscapes, i.e. the town centre (150 ha) and the residential area (2,224 ha). In total, 222 Magpie nests were found and their height, tree species and nest-site type determined. Nests were found in 25 tree and two shrub species, the most of them (31.1%) being placed in the commonest tree species in the town, the Common Hackberry Celtis occidentalis. The majority of the nests were found in tree avenues (39.6%) and groups of trees (31.5%). Nests in the town centre with a mean height (± SD) of 15.2 ± 4.05 m were significantly higher than those in the residential area with a mean height (± SD) of 11.4 ± 5.13 m. The mean distance of nests from the top of the canopy (± SD) was 1.5 ± 1.33 m, demonstrating the Magpie's tendency to place its nests in the very tops of trees in the urban areas. In the residential area, nests were present in every height class, while in the town centre they were not found lower than 5 m. This difference can be explained by denser human population in the town centre and hence greater disturbance (e.g. pedestrians), as found in several other studies, but also by the negative effect of high buildings that prevail there. Thus, the height of surrounding buildings, too, might play an important role in nest-site selection in Magpies breeding in urban habitats, especially in densely built-up areas. Breeding density of Magpie in Sombor was 0.94 pairs/10 ha, with almost twice as high in the town centre as in the residential area. The findings of this study are compared to those obtained in other studies in Serbia and abroad.

Pozvetek

Objavljanje in osnovna analiza obročkovalskih podatkov sta sicer pogosti temi člankov, redko pa so objavljeni podatki iz posameznega mesta, kot je denimo Sombor v premalo raziskani regiji Srbije. Predstavljamo podatke o obročkanju in ponovnem ulovu plavčkov Cyanistes caeruleus in velikih sinic Parus major za obdobje 32 let. Dodatno smo preverili vpliv povprečne najvišje temperature jeseni (september-december) in pozimi (januar-marec) na njihovo številčnost ter pojavljanje v dveh osnovnih habitatnih tipih (parki in vrtovi) v mestu Sombor. Skupno smo obročkali 1675 plavčkov (ponovno ujeti osebki N = 407) in 8062 velikih sinic (ponovno ujeti osebki N = 1517). Pri obeh vrstah so prevladovali mladi osebki (koda EURING 3 oz. 5). Najstarejše obročkane ptice obeh vrst so bile mlajše kot zabeleženo v drugih evropskih raziskavah. Številčnost obeh vrst ni bila povezana s povprečno najvišjo jesensko oziroma zimsko temperaturo. Število obročkanih ptic v parkih in vrtovih se ni pomembno razlikovalo. Glede na ugotovitve predhodnih raziskav sklepamo, da je njihova številčnost v posameznem habitatnem tipu odvisna od razpoložljivost hrane in vremenskih razmer, ne pa drugih okoljskih dejavnikov.

Abstract

Understanding the migration routes of the Central European Spoonbill population is important for their conservation. Here we analysed movements of 3186 individuals of Eurasian Spoonbills marked with colour rings in the Carpathian Basin (Hungary, Croatia and Serbia) between 2003 and 2015, and a satellite tagged individual, which was equipped in Italy in 2013, and later moved to the Carpathian Basin. Migration routes of these Spoonbills predominantly followed the Adriatic Flyway, however, some birds were also found to both east and west from this flyway. We identified 59 stopover sites, 55 of which were located along the Adriatic Flyway. Colourringed juveniles (1cy), on average, spent 4.0±0.9 (SE) days on the stopover sites along the Adriatic Flyway during autumn migration, while non-juveniles (> 1cy) spent 2.6±1.0 (SE) days during autumn and 2.1±0.4 (SE) days during spring migration there. These durations were not significantly different. Duration of stops of the satellite tracked individual was between 7 and 15 days during autumn and between 1 and 12 days during spring migration. Our results indicate the existence of two alternative routes of the Adriatic Flyway between the Carpathian Basin and the wintering areas in southern Italy and the central part of coastal North-Africa. The North-Adriatic Flyway includes stopover sites in north-eastern Italy at the river mouth of River Isonzo, Lagunes of Venice and wetlands around River Po. The South Adriatic Flyway leads through the Balkan Peninsula, with stopover sites at the karst lakes of Bosnia and Herzegovina, mouth of the river Neretva (Croatia), Ulcinj Salinas (Montenegro) and wetlands in Gulf of Manfredonia (Italy). This hypothesis was also supported by the migration of the satellite tagged individual, the paths of which was described here in detail. The average coordinates of spring and autumn stopover sites were located at different parts of the flyway: it was in south-western Italy during autumn migration, while it was close to the western coast of the Balkan Peninsula during spring migration. We found examples for Spoonbills using the same migration paths along the same route year by year on both spring and autumn migration, but also noticed shifts between routes. Some observations indicate that individuals may show site fidelity to stopover sites between years, although the sample size was low for statistical significance.