White-tailed eagles regularly winter under the Veľká Fatra.
The white-tailed eagle ( Haliaeetus albicilla) is the largest nesting bird of prey in Slovakia. Females reach respectable dimensions: body length up to 80 cm, wingspan up to 240 cm, and weight can reach up to 8 kg in some cases! It has a massive, yellow-colored beak in adulthood and a paler head than the rest of its body. A typical feature is a white wedge-shaped tail. Young birds acquire their typical coloration only in the fifth year of life, when they also become sexually mature.
In Slovakia, 10-14 pairs nest and 60-90 individuals winter. The species tends to keep expanding. A typical habitat of this species are lowlands with large water bodies and forests close to water bodies (Danube region, East Slovak plain, Záhorie). In the north of the territory, the only known nesting site is at the Orava Dam.
The white-tailed eagle is not a very skilful hunter on land and therefore in winter it becomes a typical carcass with an important sanitary function. Due to its cumbersome flight, it cannot harm small mammals or hunting species such as hares, foxes or pheasants. Despite this, it is perceived negatively by the hunting public and is referred to as a predator of small game. There are known cases of carbofuran poisoning, especially from southern Slovakia. Bird crime has long been dealt with by RPS – Protection of Birds of Prey in Slovakia. https://www.dravce.sk/vtaciakriminalita/index.php/nelegalna-cinnost/formy-nelegalnej-cinnosti/cielove-skupiny
On water surfaces, however, the white-tailed eagle can deftly catch a larger fish, or it waits on a piece of ice for the current to swim away in the river. It can also catch waterfowl. His hunting strategy is relatively simple. Until then, it flies on flocks of ducks or other waterfowl, until they are exhausted by diving and emerging from the water, and at the next breath it deftly grabs them from the surface.
White-tailed eagle ( Haliaeetus albicilla) captured on webcam with feeds on cadavers, which were first discovered by golden eagles.
In the mountains of the Veľká Fatra, however, these predators also adopted another ingenious strategy for obtaining food. Eagles have perfect eyesight, they can spot the circling golden eagle (Aquila chrysaetos) even at 10-15 km directly from the basin and automatically associate it with food and fly to check it. The result is often a rich feast of cadavers of deer, wild boar or roe deer, which could primarily have been torn down by wolves and subsequently discovered by golden eagles. It is an example of perfectly functioning interspecific kleptoparasitism, which reduces the time and energy costs of animals to obtain live prey (or non-living cadavers), but increases the risk of injury because they have stepped into the territory of another pair or species. Also in this case, the eagles have the upper hand, as they are favored by their size. Golden eagles guard their food sources very carefully and do not tolerate cadavers or members of their own species on what they find, unless it is a family ties. But compared to the size superiority of the eaglet, they can’t do anything. They often nervously rush into it and eventually give up. However, the memory and intelligence of golden eagles is significantly higher than that of golden eagles. The eagles will wait and return to their prey, even if it is all under snow, they remember the place exactly. Eagles often do not remember the place where the cadaver was found.
Golden eagles (Aquila chrysaetos) guard their prey from members of their own species, but also from other predators. In the territory, they tolerate only relatives.
A parent pair of golden eagles in front of an online camera on “Dravčá skala”
A young female golden eagle ( Aquila chrysaetos), which the parent couple tolerates in their territory even in the second year of life.
Golden eagles can “pull” eagles in this way even to altitudes where no one would expect them. There are also known observations in the area of Rovní – Gaderská valley and Krížná. You can see the eagle that we managed to document with an online camera on the “Predator’s Rock” here: KUKAJ.SK . The eagles pulled it to an altitude of about 1000 m above sea level. It was an immature bird around 4 years of age. At the age of 5, the coloration of the eagles stabilizes and they acquire a typical white tail. However, complete stabilization can only be said to be around the age of 10. Until then, small dark spots may still show on the wedge-shaped tail. “Our” eagle still had a too spotted tail.
Every year, 2-4 eagles winter in the foothills of the Veľká Fatra in the area of the Turčianska Basin, which fly along the Váh to the Žilina Dam and in the opposite direction to the Párnické gravel pit and the Orava Dam. In the years 2010 – 2013, the white-tailed eagles also performed wedding flights over the Krpelany Dam, but nesting still did not take place. Also interesting is the data of an adult individual who stayed and hunted at the Krpelianska dam in the summer of 2017. We firmly believe that this majestic predator will soon be included among the nesting birds of the Malá or Veľká Fatra.
Text: Ing. Juraj Žiak
Photo: Juraj Žiak, Ivan Darani
