One of the ultimate signs here in Sweden (and Northern Europe) of winter is coming is the moving south of the common crane (Grus grus) for the winter.
I live not far from the last major stop for their migration north in the spring, so we have good opportunities to see them here at least twice a year. Most move further north to spend summer, but some stay around. In autumn they do not gather in the large numbers they do in spring, but move in sometimes quite large groups, in V formation. A few weeks ago I saw the biggest flock I ever saw, maybe 150 in several V groups. Last week I saw a smaller group, about ten individuals. Two days ago, I heard a flock, too. They make a easy recognisable sound. They were really stragglers, probably slowed down by the periodically bad weather recently (was weirldly warm a while ago, too). I hope they all make it safely to warmer places.
It is always a bit sad sign to see them abandon us here before the winter comes. Can't be helped.