Kakiyats eagle was the first Berkut I ever handled. She was a big tough, rough gentle girl, but bore the scars of many a fox encounter.
Her feather condition was a lot dryer than I was use to with my eagles, who live in a very much more temperate climate.
Eagles in Northern Europe, especially in the UK, preen their feathers regularly to improve the water proofing. They can sit out in the heaviest of downpours and remain essentially dry.
Kakiyats eagles feather condition was more like a desert falcon, part of this was because she had not completed a good moult that year and those older feathers were tired. The rest was possible down to the very dry climate she lived in, and the lack of possibility to have a good bath.
Two reasons for this was the dry sand dust or rock the ground surface consisted of. A wet eagle leaving a bath pan would soon become a mud ball, and most importantly all water was ice in this very low temperature.