White-tailed Eagle (also known as Sea Eagle or Erne)

A massive raptor with a wingspan up to 2.4 meters. Adults have a distinctive white tail and pale head, but immatures (like the owner of this feather) are darker with mottled brown and white patterns throughout. They are known for their 'barn door' wing profile in flight.

Features a mottled 'salt and pepper' or terminal banding pattern. The base is creamy-white transitioning into grayish-brown irregular bars and spots. This specific variegated pattern is typical of sub-adult (immature) plumage before they reach the solid brown body of adulthood.

The lower portion is highly plumulaceous (downy) for insulation, transitioning to a pennaceous (interlocked) structure toward the tip for water shedding and protection. The barbs are relatively coarse.

The rachis is thick, white, and robust, providing strong structural support. Barbs are densely packed; the dark pigments are concentrated in wavy horizontal bands across the vane.

The surface is matte and slightly coarse. It feels stiff at the tip but very soft and silky at the downy base. It lacks the oiliness of waterfowl feathers but is highly durable.

Originated from the lower back, flank, or upper tail coverts. The high ratio of downy base to structured tip is characteristic of feathers providing insulation near the bird's rear or undercarriage.

Large size, thick white rachis, and the distinctive irregular brown-on-cream banding/mottling which is diagnostic for immature Haliaeetus species in Europe.

Coastal cliffs, large freshwater lakes, and river deltas. Lonjsko Polje provides the perfect swampy, flooded forest habitat rich in fish and waterbirds.

Found across Northern Eurasia. In Croatia, they are concentrated along the Sava and Drava river basins and coastal areas. High density in the Lonjsko Polje Nature Park.

Apex predator and scavenger. They play a vital role in cleaning ecosystems by eating carrion and controlling populations of waterfowl and fish.

Lesser Spotted Eagle (smaller, different banding) or juvenile Golden Eagle (darker, usually has a more defined white base on tail feathers rather than mottling throughout).

The White-tailed Eagle is the national symbol of Poland and was the inspiration for the German Federal Coat of Arms. They are incredibly long-lived, reaching up to 20-25 years in the wild.

Historically significant in European heraldry. Feathers were used in various indigenous shamanic practices in the far north. Under modern law, they have no legal commercial use.

Look under large nests (eyries) in oak or poplar trees near water. Molting typically occurs in late spring and summer. Lonjsko Polje is one of the best places in the Balkans to find them.

Fair to Good. The feather shows some 'weathering' and separation of barbs at the edges, suggesting it was molted naturally and spent some time on the ground before being found.

i found this in a bird reserve Lonjsko Polje, Croatia, a swampy area