Long-legged Buzzards from the Balkan and Russia are mostly migratory and spend the winter in northern Afrika or in the Sahel. Some birds spend the winter in Hungary or Greece. Sometimes Long-legged Buzzards are seen farther in the west, for example in Austria and Germany.
A map on Wikipedia shows that the ones found in India are in a mixed range, some are winter migrants and some are part of the permanent range.
https://en.wikipedia.org/wiki/Long-legged_Buzzard
https://www.europeanraptors.org/raptors/long_legged_buzzard.html
