Population size, distribution and habitat selection of the white-tailed eagle Haliaeetus albicilla in the alluvial wetlands of Croatia

Abstract

From 2003From -2006, research on the breeding distribution of the white-tailed eagle (Haliaeetus albicilla) was conducted in Croatia in order to assess the size of the national population. In 125 locations, clear signs of breeding activity were found. An additional 10 presumably active territories were detected but it was not possible to locate the exact position of the nests and confirm the breeding. Based on this, it is concluded that the national breeding population is not less than 135 breeding pairs. The present distribution can be compared with previous reports with the exception of the area along the Ilova and Lonja rivers that have never been reported as an important breeding site. Analysis of the characteristics of 138 nest positions as well as preferences/avoidance of specific structural features were performed. The results showed that white-tailed eagles prefer to build their nests on pedunculate oaks, narrow-leafed ash and white poplars with the greatest preference for mature trees with a diameter above 92.5 cm. The minimal distance between two active pairs was 348 meters. More than 50% of the national population breed less than two km from a large water area and 95% of the population less than four km. More than 95% of the population breed at altitudes lower than 140 m above sea level and are further than one km away from the nearest human settlement, regardless of the availability of forests. According to several parameters (distance to a large water area, elevation, forest presence, distance to the nearest settlement, distance to highways and railways) geographic information system (GIS) helped to determine potential white-tailed eagle breeding areas.

Nest-site selection, breeding success, and diet of white-tailed eagles(Haliaeetus albicilla) in the Danube Delta, Romania

“…The practice of building nests in taller trees may have a close connection with increased traffic inside the delta, started by aggressive polder creation in the early 1960s, and continued by uncontrolled tourism development in the 1990s (Gâştescu and Ştiucă, 2006). This phenomenon is similar to the situation found in most surveys in central or eastern Europe, with low-positioned nests disappearing totally (Horváth and Pintér, 2005;Radović and Mikuska, 2009;Vrezec et al, 2009;Rajchard et al, 2010). White-tailed eagles select nest sites preferentially on large trees, without a specific tree species preference, usually using tree stands at short distances from favorite feeding areas (Cramp, 1980).…”

Alterations in the breeding habitats for two endangered raptor species along the Sava River basin, Croatia

“…Due to its natural values and cultural heritage, this area has been placed under protection as a nature park (Radović et al 2003) and a quarter of the white-tailed eagle (Radović and Mikuska 2009) breeding population in Croatia. Data comprises from only one nest per occupied territory even when more nests of the same pair was known (Fig.…”

“…In Central and Eastern Europe, it breeds along large rivers in the Pannonian plain (SchneiderJacoby et al 2003). It is probable that the highest breeding densities are found in alluvial wetlands in Croatia: Sava River Basin with Nature Park Lonjsko Polje as its part and Kopački rit Nature Park (Schneider-Jacoby et al 2003;Radović and Mikuska 2009). These areas are crucial for the preservation of Pannonin population of both species, and both alluvial wetlands are still well preserved (SchneiderJacoby et al 2003) but are facing actual threats from infrastructural plans once forgotten but which have been revived again in the recent past (Brundić et al 2001;Schneider-Jacoby 1996).…”

“…The white-tailed eagle's European status was classified as Rare, "SPEC 3" (Tucker and Heath 1994), until 2000 when it was classified as lower risk/near-threatened; its current status is Rare, "SPEC 1" (BirdLife International 2004). Comprehensive status and breeding biology of the species in Croatia can be found in the work of Radović and Mikuska (2009).…”

“…Hunting and poaching as well as intensification of agricultural production and management of the forests were the main recognised threats for the lesser spotted eagle in Croatia (Radović et al 2003). Forest management still is not recognised as threat for white-tailed eagle on a national level but the species is facing additional threats in pollution of water, disappearing wetlands and collapse of extensive freshwater fish production (Radović and Mikuska 2009), so simultaneous the In this paper, we focus on accessing the impact of forestry practices on the quality of habitats for two endangered raptor species in recent past. Additionally, we are testing the usefulness of HIS modelling in combination with widely available databases like Corine Land Cover Change database in detecting habitat changes for certain species, possibly before those changes can even be reflected on population parameters (as demonstrated by Doak 1995).…”